DESNZ conversion factors
Per kWh, litre, tonne-km or night: physical activity × a factor for that activity.
One set per activity year; the 2026 set was published on 11 June 2026.Software · spend-based accounting, cited
Spend-based carbon accounting software: what an EEIO factor measures, and when to move on
Spend-based carbon accounting software multiplies what you spend in each category by an emissions-per-pound factor from an input-output model, which makes a whole Scope 3 inventory possible from the ledger alone.
This page sets out how those factors work, where the method is accepted, when a category should move to better data, and how to test a product, then lists 60 vendors in their own words; this site has tested none and ranks none.
What spend-based software does
Six steps, from ledger line to labelled estimate
Spend-based carbon accounting software estimates emissions from money spent rather than from physical quantities.
The GHG Protocol’s guidance on purchased goods and services describes the method as collecting the economic value of goods and services purchased and multiplying it by the relevant environmentally-extended input-output (EEIO) emission factors.
It is the usual way an organisation gets a first view of its whole Scope 3 inventory, because every purchase already sits in the ledger with an amount and a supplier.
The rest of the calculation, from boundary to restatement, is the same as in any carbon accounting software; this page covers only what the spend-based route adds.
- 1
Extract
Purchase lines from the general ledger, purchase ledger or ERP, by supplier, account and period.
- 2
Exclude
Lines that are not purchases of goods or services, and energy already counted on activity data.
- 3
Map
Each account or supplier to an economic sector the factor set recognises.
- 4
Align
Currency, price year and tax treatment brought to the basis of the factors.
- 5
Multiply
Spend × the sector’s emissions per unit of spend, with the factor release stored.
- 6
Label
Each category tagged spend-based, so it can later move to supplier or activity data on its own.
How an EEIO factor is built
National emissions, shared out by money
An EEIO factor is a sector average: the emissions of a whole sector’s supply chain divided by the money that flows through it.
The GHG Protocol’s Technical Guidance explains that EEIO models are derived by allocating national greenhouse gas emissions to groups of finished products based on economic flows between industry sectors.
The output is typically a quantity of greenhouse gases per unit of revenue in a sector, usable as a cradle-to-gate factor for that sector’s products.
The same guidance says EEIO data is particularly useful for screening emissions sources when prioritising data collection.
Read the advantages and disadvantages, in the guidance’s words
| The Technical Guidance lists as an advantage | And as a disadvantage |
|---|---|
| Comprehensive coverage of the entire economy, so no emissions source is outside the boundary | Broad sector averages may not represent unique processes and products |
| Simplicity of method and application | A linear link between money and emissions gives only indicative results; products of different value within one sector cannot be told apart |
| Time and cost savings, because the data requirements are less onerous than a process-based approach | It lacks the specificity and accuracy of process-based approaches |
| — | It is difficult to measure and demonstrate the results of reduction efforts |
| — | EEIO databases are generally limited to a specific geographic region |
Companies may combine EEIO and process-based data, the guidance adds, and must report the types and sources of data used for each Scope 3 category.
The geographic point matters in the UK: UK SRS S2 ¶B51 asks an entity to prioritise emission factors that relate to the jurisdiction where the activity took place, under the standard.
Inside an EEIO factorExplore
Module 01 / 04
National emissions
The economy’s emissions, the starting total the model shares out.
Module 02 / 04
Flows between sectors
Input-output tables of what each sector buys from every other.
Module 03 / 04
Allocation to products
Emissions allocated to groups of finished products along those flows.
Module 04 / 04
A factor per unit of spend
Cradle-to-gate emissions per unit of money, sector by sector.
The UK multipliers
Defra’s multipliers are not the DESNZ conversion factors
The UK government publishes two different sets of factors, and spend-based software uses the second.
DESNZ’s 2026 methodology paper says at ¶1.6 that its conversion factors “differ from the spend-based emissions multipliers currently published by” Defra alongside the UK and England carbon footprint statistics.
The same paragraph says Defra’s multipliers are primarily intended to compare the carbon intensities of different categories of final UK demand, but can give “an initial assessment” of a user’s full supply-chain emissions from spending.
It adds that users may wish to use spend-based methods where they lack data for activity-based methods, and should report the methods they use.
Read what Defra publishes, and what this page does not print
Defra’s carbon footprint page carries a dataset titled “Spend-based emissions multipliers, 1997 to 2023”, updated as part of the annual update on 30 June 2026, with corrections to the page on 7 and 24 July 2026.
The release is produced with a multi-regional input-output model developed for Defra by the University of Leeds.
Defra says its earlier releases are superseded with each annual update, because estimates for previous years are subject to revision, so the same year’s multiplier can differ between releases.
This site has not opened the multipliers spreadsheet itself, so this page prints no multiplier value, unit or price basis: read them in Defra’s own dataset and its methodology note.
The activity-based sets, year by year, are on GHG conversion factors.
UK government
factors
factors
Defra spend-based multipliers
Per unit of spend by product category, from the UK carbon footprint statistics.
An initial assessment of supply-chain emissions where activity data is lacking.Price and inflation effects
A spend-based figure moves with prices, not with emissions
Because the factor is emissions per unit of money, anything that changes the price changes the estimate.
A price rise reads as an emissions rise, a discount reads as a cut, and a supplier that halves its own emissions at the same price changes nothing in your inventory.
The GHG Protocol’s Chapter 1 guidance therefore lists, among the data the spend-based method needs, “where applicable, inflation data to convert market values between the year of the EEIO emissions factors and the year of the activity data”.
The GHG Protocol’s Scope 3 material also warns that spend and revenue may not correlate well with emissions, which is the same problem seen from the other side.
Read what this means for a reduction claim
The Technical Guidance names, among EEIO’s disadvantages, that it is difficult to measure and demonstrate the results of reduction efforts.
So a fall in a spend-based category can be a smaller budget, cheaper suppliers or deflation, and the inventory cannot tell which.
Reporting a reduction from a spend-based category without saying so risks overstating it; the same care applies to the 2025–26 fall in the UK electricity factor, set out on the conversion factors page.
| What changed this year | Spend | Spend-based estimate | Real emissions |
|---|---|---|---|
| Supplier raises prices 10%, same goods | +10% | +10% | No change |
| Supplier gives a 10% discount, same goods | −10% | −10% | No change |
| Supplier halves its own emissions, same price | No change | No change | Down |
| You buy 10% more of the same goods at the same price | +10% | +10% | Up, roughly |
Currency, price year and the base year
Four settings a spend-based line must carry
A spend-based figure is only reproducible if the line records what it was converted from.
The Technical Guidance, in its investments chapter, says reporting companies should account for any significant changes in exchange rates and inflation rates over time when using EEIO data.
So an invoice in euros or dollars needs a stored rate, date and source before it meets a sterling factor, and the choice should stay the same from year to year.
Defra revises earlier years with each release, so the release used belongs on the line as much as the year.
Read how a method change reaches the base year
The GHG Protocol’s 2019 Inventory Guidance lists significant changes in calculation methodology among the triggers for recalculating a base year, alongside structural changes and significant errors.
It sets no figure for “significant”: the company determines its own threshold and discloses it.
Moving a large category from spend-based to supplier data is a methodology change of exactly that kind, so the base year may need restating on the new method while the original stays on record.
UK SRS S2 ¶29(a)(iii) separately asks for any changes to the measurement approach, inputs and assumptions during the period and the reasons for them, under the standard.
Settings on every lineExplore
Module 01 / 04
Currency
The currency of the spend, and the rate, date and source used to convert it.
Module 02 / 04
Price year
The year of the factors and of the spend, with any deflator used between them.
Module 03 / 04
Factor release
Which publication of the multipliers was used, since later releases revise earlier years.
Module 04 / 04
Base year
The method and release behind the base-year figure, kept beside any restatement.
Where spend-based is acceptable
Accepted for Scope 3, never for the energy lines
Spend-based estimates are accepted for Scope 3 by every instrument that UK reporters use, with a preference for better data where it exists.
The GHG Protocol’s Technical Guidance ranks the methods from most to least specific and says companies “need not always use the most specific method as a first preference”.
UK SRS S2 ¶B57 contains the presumption that Scope 3 can be estimated reliably using secondary data and industry averages, while ¶B47 asks an entity to prioritise primary data, all else being equal.
SECR is different: it asks for energy use in kWh and emissions from gas, electricity and transport fuel under Schedule 7, which no spend-based estimate can produce.
Read the rules, instrument by instrument
| Instrument and status | What it says about spend-based data | Provision |
|---|---|---|
| GHG Protocol Scope 3 Standard · voluntary standard | Account for all Scope 3 and justify exclusions; describe the types and sources of data for each category, and the share from suppliers | §6.2; Chapter 11 |
| GHG Protocol Technical Guidance · guidance, not requirements | Spend-based is the least specific method; choose per activity on size, goals, data availability, data quality and cost | Introduction; Chapter 1 |
| DESNZ conversion factors methodology · government guidance | Defra’s multipliers give an initial assessment where activity data is lacking; report the methods used | ¶1.6 |
| UK SRS S2 · voluntary; comply or explain for listed companies in UKLR 6, 14, 15, 16 and 22 for periods from 1 January 2027 | Secondary data presumed adequate for Scope 3; primary data prioritised all else equal; disclose the extent measured from specific activities and verified inputs | ¶¶B47, B49, B56, B57 |
| SECR · in force | Energy in kWh and emissions from gas, electricity and transport fuel; spend cannot supply them | SI 2008/410 Sch 7 |
UK SRS S2 ¶B49 names industry-average data from published databases and government statistics as secondary data, which is what an EEIO multiplier is.
Listed companies under the FCA’s PS26/19 report on a comply-or-explain basis, with a one-year Scope 3 relief; the detail is on UK SRS Scope 3 reporting, and the standard itself on UK SRS S2.
What SECR’s lines require, one by one, is on SECR reporting requirements.
GHG Protocol
Least specificRanked after supplier-specific, hybrid and average-data; not always last choiceUK SRS S2 ¶B57
Presumed reliableScope 3 from secondary data and industry averagesUK SRS S2 ¶B47
Primary firstWith all else being equalSECR
Not usableEnergy in kWh, from bills, meters and fuel recordsWhich categories can start on spend
5 of the fifteen categories list a spend-based method
The GHG Protocol’s guidance lists a spend-based method for categories 1, 2, 4, 6, 9; the other categories are calculated from physical, site or investment data.
A product that applies spend multipliers everywhere is estimating categories the guidance would calculate another way.
| Category | Calculation methods listed in the guidance | Spend-based listed |
|---|---|---|
| 1. Purchased goods and services | Supplier-specific, hybrid, average-data, spend-based | Yes |
| 2. Capital goods | Supplier-specific, hybrid, average-data, spend-based | Yes |
| 3. Fuel- and energy-related activities | Supplier-specific, average-data | No |
| 4. Upstream transportation and distribution | Fuel-based, distance-based, spend-based (transport); site-specific, average-data (distribution) | Yes |
| 5. Waste generated in operations | Supplier-specific, waste-type-specific, average-data | No |
| 6. Business travel | Fuel-based, distance-based, spend-based | Yes |
| 7. Employee commuting | Fuel-based, distance-based, average-data | No |
| 8. Upstream leased assets | Asset-specific, lessor-specific, average-data | No |
| 9. Downstream transportation and distribution | Fuel-based, distance-based, spend-based (transport); site-specific, average-data (distribution) | Yes |
| 10. Processing of sold products | Site-specific, average-data | No |
| 11. Use of sold products | Direct and indirect use-phase methods | No |
| 12. End-of-life treatment of sold products | Waste-type-specific | No |
| 13. Downstream leased assets | As for category 8; the guidance says the methods do not differ | No |
| 14. Franchises | Franchise-specific, average-data | No |
| 15. Investments | Investment-specific, project-specific, average-data | No |
Category 1, purchased goods and services, is where most spend-based estimates sit, and the subject as a whole is on Scope 3 emissions.
When to move a category
Screen on spend, then spend the effort where it counts
Move a category off spend when it is large and its data is weak, because that is where better data changes the answer.
The Scope 3 Standard’s data-quality chapter, §7.3 of the Standard, points improvement first at sources with relatively low data quality and relatively high emissions.
The Technical Guidance lists the criteria for choosing a method: the relative size of the emissions, business goals, data availability, data quality, cost and effort, and others the company identifies.
It also allows different methods for different activities within one category, so the largest suppliers can move to supplier data while the long tail stays spend-based.
Read the guidance’s own example, and the reduction point
The guidance’s example is a coffee company that collects primary data from the ten suppliers making up most of its beans, and uses secondary factors, average-data or spend-based, for a small purchase of sugar.
A second reason to move is reduction: a supplier’s own lower figure reaches your inventory only through supplier-specific or hybrid data, never through a sector average.
UK SRS S2 ¶B48 counts supplier-specific emission factors for purchased goods or services as primary data, under the standard.
Supplier engagement as a product category is covered on carbon management software.
- 1
Screen
A complete spend-based inventory shows where the emissions probably sit.
- 2
Rank
Order categories and suppliers by size of estimate and weakness of data.
- 3
Choose a method
Average-data on physical quantities, or supplier-specific and hybrid from the largest suppliers.
- 4
Move one category
Recalculate it alone; everything else stays as it was.
- 5
Disclose
The change, its reason, and any base-year restatement.
Recording the method
One record per category, so one category can move alone
The capability that matters most in spend-based software is a method stored per category, not a method inferred from a total.
Chapter 11 of the Scope 3 Standard asks, for each category, for a description of the types and sources of data, including activity data and emission factors, a description of data quality, and the percentage of emissions calculated from data obtained from suppliers or other value-chain partners.
UK SRS S2 ¶B56 asks for the extent to which Scope 3 is measured using inputs from specific activities and verified inputs, which a product can compute only if each category carries its method.
The test is simple: move one category to supplier data on a demonstration and check that nothing else recalculates and the change is recorded with its reason.
Read why the record serves the GHG Protocol’s principles
The Corporate Standard asks for consistency, so methods can be compared over time, and transparency, so the working behind a figure is visible.
A product that rebuilds the whole inventory when one category changes breaks both: last year cannot be reproduced, and no one can say which change moved the total.
The wider test list for the measurement layer is on carbon accounting software, and the GHG mechanics, including restatement, on GHG accounting software.
| Field | Why it is needed |
|---|---|
| Category and activity | Methods can differ by activity within a category |
| Method | Supplier-specific, hybrid, average-data or spend-based |
| Data source | Ledger, purchasing records, supplier response, meter |
| Factor source and release | Which database or supplier figure, and which publication |
| Currency and price year | How the spend was converted and deflated |
| Share from suppliers | The Scope 3 Standard asks for it per category |
| Changed on, by whom, why | UK SRS S2 ¶29(a)(iii) asks for changes and reasons |
Accounting-ledger integrations
The ledger holds the spend, and the traps
Most spend-based software starts from an export or a connection to the accounting system.
The GHG Protocol’s Chapter 1 guidance names internal data systems such as enterprise resource planning systems, bills of materials and purchasing records as the sources of spend data.
The mapping from account codes or suppliers to economic sectors is where most of the judgement sits, so ask to see it line by line and to change it.
The commonest error is double counting: an electricity or fuel bill paid through the ledger, estimated on spend, while the same energy is already in Scope 1 or 2 from meters or fuel records.
Read the integration questions
Ask which accounting systems the vendor connects to directly and which arrive by file upload, and who on your side owns the mapping each year.
Ask whether spend is taken net or gross of recoverable VAT, and whether that matches the price basis of the factors the product uses.
Ask how credit notes, accruals and prepayments are treated, because each can move spend between periods without any change in what was bought.
Ask how a supplier that sells across several sectors is mapped, because one account code can hide both office supplies and construction.
The same feeds, used for a running monthly figure, are covered on carbon emissions tracking software.
What the ledger feedsExplore
Module 01 / 04
General and purchase ledger
Supplier invoices by account and period: the core of category 1.
Module 02 / 04
Fixed asset register
Capital purchases, which belong in category 2 rather than category 1.
Module 03 / 04
Expenses and cards
Travel and subsistence for category 6, with distance where claims record it.
Module 04 / 04
Lines to exclude
Payroll, taxes, depreciation, intercompany transfers and energy already on activity data.
Expense carbon reporting
Expense claims: use the distance when you have it
Expense carbon reporting software reads expense claims and card transactions, mostly for business travel.
The GHG Protocol’s guidance lists fuel-based, distance-based and spend-based methods for business travel, category 6, so spend is one option, not the only one.
A mileage claim usually records distance, and a hotel booking records nights, and both can be converted with the DESNZ conversion factors for the activity year rather than with a spend multiplier.
Employee commuting, category 7, has no spend-based method in the guidance, so a tool that estimates it from expenses is doing something else and should say what.
Read the factor-year rule for travel
DESNZ says at ¶1.10 of its 2026 methodology paper that the 2026 factors are for activity data falling entirely or mostly within 2026, so travel in 2026 uses the 2026 set whenever the claim is paid.
Where a company is within SECR, its transport fuel is reported in kWh and emissions rather than as spend; the size test and the lines are on the SECR requirements page.
Business travel methods
ThreeFuel-based, distance-based, spend-based — category 6Employee commuting
No spend methodFuel-based, distance-based, average-data — category 7Mileage claims
DistanceUsually record miles, so distance-based is openHotel stays
Activity factorDESNZ publishes hotel-stay factorsWhat vendors say about spend-based Scope 3
6 vendors whose own pages describe a spend-based route
These are the vendors in this site’s registry whose own Scope 3 page, as read, mentions spend; each line is the vendor’s statement about itself.
A vendor missing from this table may still offer spend-based Scope 3: the registry records only what was found on the pages read.
Several describe the same route this page sets out: start from spend, then replace estimates with supplier data as it arrives, which is the claim to test on your own data.
The vendors
60 carbon accounting and SME-focused vendors, in their own words
Every vendor this site files under carbon accounting or as serving small and mid-sized businesses, alphabetically, which ranks nothing, each linked to its own site and to its profile here.
The registry covers 73 vendors across all categories, read 11 October 2026 and 30 September–1 October 2026; the filter narrows this list.
60 vendors · carbon accounting, smes
“Altruistiq helps companies with complex value chains go faster and further on sustainability”
“Intelligent AI that measures, reduces, and reports Scope 1–3 and LCA emissions in line with CDP, SBTi, CSRD, and CBAM requirements”
“Benchmark Gensuite is a unified EHS management software platform built on a single architecture—connecting safety, environmental compliance, and operational risk across every site”
“Our software provides companies and financial institutions with precise accounting of the emissions caused by making, shipping and using critical commodities and products around the globe”
“Measure, reduce, and report your Scope 1, 2 and 3 emissions”
“The professional benchmarking and reporting platform built for sustainability consultants, SMEs, and the platforms that serve them”
“Coolset gives supply chain and ESG teams the structure, automation and guidance to meet complex compliance requirements like EUDR, PPWR and CSRD, and manage Scope 1-3 emissions”
“One AI-enabled EHS software platform to drive performance across employee health, safety, quality, environmental, and sustainability”
“Cozero helps enterprises steer decarbonization with the same rigor as financial performance, from data collection to investment decisions and regulatory disclosure”
“Dcycle is an ESG software platform founded in 2020 that helps companies collect, manage, and govern sustainability and non-financial data”
Diginex describes carbon accounting, sustainability reporting, supply chain, human rights monitoring and ESG investor intelligence for asset managers, banks and companies.
Diligent’s carbon accounting page describes a solution that “automatically collates your data and produces up to 80 different pre-configured audit-ready reports”.
Ecologi describes itself as a B Corp-certified climate action platform.
EcoOnline sells software to manage EHS and compliance.
“The Emitwise platform is now part of Green Project, where the team continues to build and deliver end-to-end decarbonization solutions”
“Enablon is Wolters Kluwer’s integrated software platform for environment, health and safety, PSM, and enterprise oversight, with ESG capabilities embedded as part of a broader risk approach”
“Collect, analyze, and report sustainability, financial, and risk KPIs with 10+ software modules – individually or in line with official standards”
“Manage safety, compliance, ESG, sustainability and operational risk from a platform built to keep programs reliable across sites, teams and operational change”
“The climate management platform built on AI, backed by dedicated sustainability experts”
“Measure, report, and reduce your company's emissions on one audit-ready sustainability management platform”
IBM describes Envizi as a “compliance ready solution for ESG data”.
“Ideagen Carbon Accounting is an AI-powered solution designed to address complex multi-region ESG reporting challenges in carbon accounting”
“Bring safety, environment, and quality workflows into one connected platform”
IsoMetrix sells software to “manage their environmental, health, safety, sustainability, and social risks”.
“Makersite’s Product Lifecycle Intelligence software brings together your cost, environment, compliance, and risk data in one place”
“Manglai is a platform to manage all of your environmental impact”
“Measurabl makes subjective sustainability data objective”
Microsoft Sustainability Manager
“Track and reduce your environmental impact using data and AI”
A carbon management platform that, in Novisto’s words, “simplifies the collection, calculation, and reporting of corporate carbon footprints”.
“Net Zero Now exists to provide a simple, credible and affordable route to Net Zero for SMEs and to celebrate and promote those that achieve this vitally important goal”
“Normative is a carbon accounting platform that helps companies calculate, report, and reduce Scope 1, 2, and 3 emissions using 349,000 verified emission factors”
“Novata is a sustainability data management platform built for private market investors, deal teams, banks, and companies that need a scalable way to collect, manage, and act on sustainability data”
“One digital solution for sustainability planning, data management, reporting, analysis and action - built for enterprise”
“Our platform empowers organizations to accurately measure and manage scope 1, 2, and 3 emissions with direct and actionable information”
Oracle Fusion Cloud Sustainability
“Oracle Fusion Cloud Sustainability is a new offering to capture environmental, social, and governance data for any kind of activity that has a sustainability impact”
“osapiens is the AI platform for compliance and supplier intelligence to help companies manage risk and become more resilient”
Persefoni describes software and AI tools to manage an organisation’s “sustainability data, disclosures, and performance”.
“Your certified software for reliable emissions intelligence to measure, report and reduce your carbon footprint”
“We guide businesses in understanding their emissions, empower them to develop carbon reduction plans, and supporting them on their journey to net zero”
Position Green describes “a sustainability reporting and management platform that combines powerful software with expert advisory services”.
“Pulsora is an AI-powered sustainability and carbon management platform that automates data collection, measurement, and reporting workflows for sustainability teams”
“Digitally handle occupational safety, quality, sustainability, and environmental management”
“It leverages the full power of the Salesforce ecosystem by pulling an organization’s sustainability data into one place and creating actionable insights to guide strategic decisions”
“Measure your full carbon footprint, build your net zero strategy and develop in-house expertise with a single partner”
SAP Sustainability Footprint Management
“Decarbonize your value chain and calculate your corporate and product carbon footprint at scale with ERP-centric, AI-enabled carbon management”
“Seedling is an all-in-one carbon accounting and Net Zero planning platform for businesses of up to 2000 FTEs”
ServiceNow Operational Sustainability Management
“ServiceNow Operational Sustainability Management helps organizations manage, visualize, and report on sustainability efforts and risks across environmental, social, and governance (ESG) programs”
“SimaPro is life cycle assessment software that helps organizations measure, analyze, and reduce environmental impacts using robust datasets, scientific methods, and transparent modeling”
SINAI describes “audit-grade Scope 1–3 accounting, automated compliance reporting, complete supply chain visibility” and decarbonisation planning for global enterprises.
“Small99 Hero creates a pathway to net zero for you based on your industry, outlining how long your Net Zero journey will take and how much it will cost”
“Sphera unifies risk, safety and sustainability into a single enterprise-wide view — connecting intelligence across operations, products and supply chains”
“Sweep's AI turns sustainability data into measurable business performance”
“Manage sustainability metrics intelligently in medium-sized businesses - through automated processes, AI-powered carbon accounting, and audit-proof ESG reports”
“Terrascope is an enterprise carbon management and decarbonisation platform for companies with complex supply chains”
“Trace combines AI-powered software with expert advisory support to help organisations meet their mandatory climate and sustainability reporting obligations, efficiently and with confidence”
“Unravel Carbon is the climate platform helping companies with global supply chains make data-driven decisions”
“Carbon accounting is often the first step companies take toward climate disclosure, compliance, and action—and with Watershed, it’s part of your complete enterprise sustainability platform”
Workday (supplier sustainability)
“Turn sustainable sourcing into a competitive advantage with Workday supplier sustainability solutions”
“Workiva Carbon is an end-to-end carbon accounting software solution that enables organizations to measure, manage, collaborate on, and report emissions data”
“Carbon management software with experts built in, so you can move from measurement to action without spreadsheets or one-off consulting projects”
Alphabetical, which ranks nothing. Each description is the vendor’s own words from its own site, read 11 October 2026 and 30 September–1 October 2026; prices appear only where the vendor publishes one. No product here has been tested by this site.
The registry does not record which multiplier set each product uses or how it handles prices and currency, so ask those as the first demonstration questions.
The tests before you sign
Eight questions, each tied to its provision
Each question beside this names the provision it comes from and what a passing answer looks like.
Run them on your own ledger, because a demonstration dataset never has a mis-coded account, a foreign-currency invoice or an electricity bill in purchases.
The broader capability list, regime by regime, is on carbon reporting software.
This site has tested no products
Nothing on this page is a rating, ranking or recommendation of any product.
Spend-based demo questions · tick the ones you need
The pass tests are our reading of the cited provisions.
Nothing you tick is stored or sent.
Small businesses and spreadsheets
A spend-based first footprint without a platform
A small business can build a first spend-based Scope 3 estimate in a spreadsheet, because the ledger export and the published multipliers are both to hand.
SECR reaches an unquoted company only if it is large, which means exceeding two of £36m turnover, £18m balance sheet and 250 employees, judged over two consecutive years after the first, under ¶20B of Schedule 7.
The spreadsheet stops coping when categories start moving to supplier data one at a time, when each line needs its release, currency and price year, and when last year must stay reproducible.
In this site’s registry, 13 vendors say on their own pages that they serve small or mid-sized businesses, and a product footprint is a different job, covered on carbon footprint software.
Platform against the way you work now
Current process £0 a year · quote £0 a year
Fill in all three to see the break-even hours.
Arithmetic on your own inputs.
The quote’s implementation, uplift and exit terms are in the three-year worksheet on the carbon reporting software page.
Nothing is stored or sent.
Choosing without a ranking
“Best” is a question about your ledger and your categories
There is no best spend-based product in general; the useful question is which one keeps a spend-based estimate honest and lets it be replaced.
- 01 / Ledger01
Bring a real ledger extract
With foreign-currency invoices, credit notes and an energy bill in purchases. - 02 / Mapping02
Inspect the sector mapping
Every account and supplier, with the right to change it. - 03 / Basis03
Check currency, price year and release
Stored on each line, with the deflator and exchange rate. - 04 / Move04
Move one category to supplier data
Nothing else recalculates; the change is recorded with its reason. - 05 / Restate05
Comparisons that rank for these searches are often written by a vendor that appears in its own table; read who wrote a list before you read its order.
The wider ESG reporting market, read against UK duties, is on the ESG software comparison.
Frequently asked
Spend-based carbon accounting software, answered
What is spend-based carbon accounting software?
Software that estimates emissions from what an organisation spends: it takes purchase lines from the ledger, maps each to an economic sector, and multiplies the amount by an emissions-per-pound factor from an environmentally-extended input-output (EEIO) model.
It is mainly used for Scope 3, where supplier and activity data are hardest to get.
Is spend-based carbon reporting software different from spend-based carbon accounting software?
They are usually the same product described from two ends.
The accounting layer turns spend into emissions with a recorded method; the reporting layer puts the result into a SECR, UK SRS or CDP format.
A spend-based figure in a reporting template is still a spend-based estimate, and the report should say so.
What is expense carbon reporting software?
Usually a tool that reads expense claims and card spend, often for business travel.
The GHG Protocol lists fuel-based, distance-based and spend-based methods for business travel, so a mileage claim that records distance can be calculated on distance rather than on its cost.
How accurate is spend-based emissions software?
It is a screening method.
The GHG Protocol’s technical guidance says EEIO data assumes a linear link between money and emissions and provides only indicative results, cannot tell apart products of different value within one sector, and makes reduction efforts hard to demonstrate.
Its strengths are complete coverage of the economy and low data needs.
What is EEIO emissions software?
Software built on environmentally-extended input-output models, which allocate national emissions to groups of finished products using the economic flows between sectors.
The output is an emissions factor per unit of spend for each sector.
In the UK, Defra publishes spend-based emissions multipliers built from a multi-regional input-output model developed for it by the University of Leeds.
Can my accounting software calculate my carbon footprint?
An accounting package holds the spend, which is the input to a spend-based estimate; some connect to carbon tools that apply the factors.
Check that the tool maps accounts to sectors you can see, excludes lines that are not purchases, records the factor release and price year, and keeps energy and fuel on activity data where you have it.
Is spend-based Scope 3 allowed under UK SRS S2?
Yes.
UK SRS S2 ¶B57 presumes that Scope 3 can be estimated reliably using secondary data and industry averages.
It also asks an entity to prioritise primary data, all else being equal (¶B47), and to disclose the extent to which Scope 3 is measured using inputs from specific activities and verified inputs (¶B56).
Does the GHG Protocol accept spend-based calculations?
Yes, as the least specific of the methods it ranks for purchased goods and services, after supplier-specific, hybrid and average-data.
Its technical guidance says companies need not always use the most specific method first, and that the method can differ by activity within a category, chosen on size, data availability, data quality and cost.
Can I use spend-based figures for SECR?
Not for the energy lines.
SECR asks for energy use in kWh and emissions from gas, electricity and transport fuel, so those come from bills, meters and fuel records with the DESNZ factors for the activity year.
A spend-based estimate cannot produce a kWh figure.
Are Defra’s spend-based multipliers the same as the DESNZ conversion factors?
No. DESNZ’s 2026 methodology paper says at ¶1.6 that its conversion factors differ from the spend-based multipliers Defra publishes with the UK and England carbon footprint statistics.
The multipliers can give an initial assessment of supply-chain emissions where users lack data for activity-based methods, and users should report the methods they use.
Do I need to adjust spend for inflation?
The GHG Protocol’s guidance for the spend-based method lists, where applicable, inflation data to convert market values between the year of the EEIO factors and the year of the activity data.
Without it, a price rise reads as an emissions rise.
Ask a product what it does and where it shows it.
Which is the best spend-based carbon accounting software?
This site has tested no products and names no best.
Ask which product passes tests drawn from the standards: the method, factor release, currency and price year stored per category; one category moved to supplier data without touching the rest; the base year restated while keeping the original; and energy kept off the spend-based line.
When should a category move from spend-based to supplier data?
When it is large and its data is weak, which is where the Scope 3 Standard says to prioritise improvement, or when you want reductions to show.
Spend-based figures move with prices and budgets, so a supplier’s own figure is the only way a supplier’s reduction reaches your inventory.
Has this site tested any spend-based carbon accounting software?
No. This page is built from the GHG Protocol, DESNZ, Defra, UK SRS S2 and the SECR regulations, each cited to its provision, and the vendor list quotes only what each vendor says about itself.
Sources
Primary sources
Every test on this page traces to the provision listed here.
Vendor statements are cited to each vendor’s own page.
Checked against 14 sources fromGHG Protocol (WRI, WBCSD)GHG ProtocolDepartment for Energy Security and Net ZeroDefraDepartment for Business and TradeFinancial Conduct Authority
- GHG Protocol (WRI, WBCSD)Corporate Value Chain (Scope 3) Standard — §6.2, Table 5.4 and Chapter 11
All Scope 3 accounted for, exclusions justified; per category, the types and sources of data and the share from suppliers.
- GHG ProtocolTechnical Guidance for Calculating Scope 3 Emissions — Introduction
Methods ranked by specificity; selection criteria; what EEIO data is, its advantages and its disadvantages.
- GHG ProtocolTechnical Guidance, Chapter 1: Purchased goods and services
The spend-based method, its data needs, inflation between the factor year and the activity year, and ERP data.
- GHG ProtocolTechnical Guidance, Appendix D: calculation formula summary tables
The spend-based formula by category, including transport.
- GHG ProtocolScope 3 Standard discussion paper (24 October 2024), Table 1
Which calculation methods apply to which of the fifteen categories.
- GHG Protocol (WRI, WBCSD)A Corporate Accounting and Reporting Standard — Chapter 1
Consistency, transparency and accuracy, which a method record has to serve.
- GHG ProtocolScope 1 & 2 GHG Inventory Guidance (2019)
Base-year recalculation for significant changes in calculation methodology; the company sets its own threshold.
- Department for Energy Security and Net Zero2026 GHG conversion factors methodology paper, ¶1.6 and ¶1.10
The conversion factors differ from Defra’s spend-based multipliers; the activity-year rule.
- Department for Energy Security and Net ZeroGovernment conversion factors for company reporting
The activity-based factor sets, one per year.
- DefraUK and England’s carbon footprint to 2023 — spend-based emissions multipliers
The multipliers dataset, its June 2026 update and July corrections, and the revision of earlier releases.
- Department for Business and TradeUK SRS S2 Climate-related Disclosures (PDF), ¶29(a)(iii), ¶¶B29, B47–B57
No prescribed factors; primary data first, all else equal; the presumption that Scope 3 can be estimated from secondary data.
- Department for Business and TradeUK Sustainability Reporting Standards S1 and S2
Published 25 February 2026 for voluntary use.
- Financial Conduct AuthorityPS26/19 — final rules on UK SRS reporting by listed companies
Comply or explain for periods beginning on or after 1 January 2027, with a one-year Scope 3 relief.
- legislation.gov.ukSI 2008/410, Schedule 7 Parts 7 and 7A
The SECR lines, in kWh and emissions, and the size test.