A person or household
Energy, driving, flights and rail; no standard governs it.
This page or the household calculator.Tool · carbon calculator, 2026 factors
Carbon calculator: one sum, three choices
A carbon calculator multiplies what you did — kWh, litres, miles, kilometres — by a conversion factor, and adds the results into tonnes of CO2 equivalent.
Use the one below for a person or an organisation on the UK’s 2026 factors, and the checks further down to judge any other calculator’s answer.
The calculator
How much carbon does your activity produce?
Pick a household or a small business, then enter a year of figures.
Carbon footprint · DESNZ 2026 factors
Enter car miles or fuel litres for the same journeys, not both.
Estimated business footprint: 21.10 tCO2e a year
Home or premises11.36 tCO2e
Road8.86 tCO2e
Travel0.88 tCO2e
| Line | Factor (kgCO2e) | tCO2e |
|---|---|---|
| Grid electricity | 0.13096 / kWh | 5.89 |
| Natural gas (as billed) | 0.18231 / kWh | 5.47 |
| Car miles (if you do not know the fuel used) | 0.26699 / mile | 2.40 |
| Petrol bought | 2.07500 / litre | 0.00 |
| Diesel bought | 2.58354 / litre | 6.46 |
| Domestic flights (one-way km × trips) | 0.22928 / passenger km | 0.28 |
| Short-haul flights to or from the UK | 0.12786 / passenger km | 0.51 |
| Long-haul flights to or from the UK | 0.15282 / passenger km | 0.00 |
| National rail | 0.03092 / passenger km | 0.09 |
Factors: DESNZ conversion factors 2026 (flat file, revised July 2026) · electricity from the 2026 methodology paper, Table 9. Flights include radiative forcing.
For 2026 activity. DESNZ publishes these factors for company reporting; used for a household they give an estimate, not a measured figure. Nothing is stored or sent.
Three routes
Whose emissions is your calculator counting?
A person’s calculator has no governing standard; it borrows company-reporting factors and gives an estimate.
An organisation’s follows the GHG Protocol Corporate Standard or ISO 14064-1, which set the boundary and sort results into scopes.
A product’s follows ISO 14067 or the GHG Protocol Product Standard, which work stage by stage through the life cycle; use the product carbon footprint calculator.
A carbon
question
question
An organisation
Scope 1, 2 and 3 under the GHG Protocol Corporate Standard or ISO 14064-1.
The business calculator, then software.One product
Life cycle stages under ISO 14067 or the GHG Protocol Product Standard.
The product calculator.The sum
What does every carbon calculator actually do?
Every line is activity multiplied by a factor: 1,000 kWh of grid electricity at 0.13096 is 130.96 kgCO2e on the 2026 set.
The factor already folds methane and nitrous oxide into CO2e using the IPCC’s fifth assessment values, 28 and 265, per ¶1.9 of the methodology paper.
So two calculators that disagree have used a different factor, a different year or a different boundary, and a good one shows all three.
One sum, four partsExplore
One sum, four parts
Activity
kWh, litres, miles or passenger km, from bills and bookings.
Judging a calculator
How do you know a carbon calculator’s answer is any good?
| Check | A good calculator | Source |
|---|---|---|
| Factor source | Names the set: for UK reporting, DESNZ | DESNZ collection |
| Factor year | Matches the year of the activity | DESNZ ¶1.10 |
| Electricity method | Says location-based, market-based or both | GHG Protocol Scope 2 Guidance |
| Flights | Says whether radiative forcing is included | DESNZ flat file |
| Boundary | Lists what is left out, especially Scope 3 | GHG Protocol Scope 3 Standard |
| Gas units | Uses gross kWh for UK supplier bills | DESNZ ¶2.9 |
Electricity is the commonest disagreement: UK SRS S2 requires a location-based Scope 2 figure, per the standard, while a market-based figure uses your supplier’s contracts.
When it matters
When does a carbon calculation become a report someone checks?
SECR size test
Two of three£36m turnover, £18m balance sheet, 250 employees2026 grid factor
0.13096kgCO2e per kWh generatedFactor sets a year
OnePublished by DESNZ each JuneAn estimate is enough until someone relies on the figure: a customer, a public buyer or the directors’ report.
From that point the figure needs evidence behind each line and last year kept as it was reported, which is what carbon accounting software is bought for.
Read about using a result in a claim
A footprint in an advert or on a label is an environmental claim under the Green Claims Code and CAP Code section 11.
From estimate to reportExplore
From estimate to report
Your own use
An estimate is enough.
From estimate to report
A customer asks
A Carbon Reduction Plan may be required in major government contracts.
From estimate to report
UK SRS
Comply or explain for listed companies, periods from 1 January 2027.
Order of work
What should you do with the number?
- 1
Keep the inputs
File the bills and bookings behind each figure.
- 2
Note the factors
Set, year, and whether flights include radiative forcing.
- 3
Find the biggest line
Act there first.
- 4
Recalculate next year
On next year’s factors, beside this year’s figure.
In one sentence
The whole page, said once
Every carbon calculator does the same sum, so judge it by the factors and the boundary it shows you.
Takeaways
Five facts, then the next step
| Fact | Source |
|---|---|
| A carbon calculation is activity × conversion factor. | DESNZ methodology |
| UK reporting uses DESNZ factors for the activity year. | DESNZ ¶1.10 |
| Organisations follow the GHG Protocol or ISO 14064-1. | GHG Protocol; ISO |
| Products follow ISO 14067 or the Product Standard. | ISO; GHG Protocol |
| UK SRS S2 requires location-based Scope 2. | UK SRS S2 |
Where to calculate nextExplore
Frequently asked
Carbon calculator, answered
What is a carbon calculator?
A tool that multiplies an activity — kWh, litres, miles, kilometres — by a conversion factor to give kilograms or tonnes of CO2 equivalent.
Every calculator does that sum; they differ in whose emissions they count, which factors they use and where they draw the boundary.
Which carbon calculator should I use?
Match it to the question.
For yourself or your household, a personal calculator; for a company, one that sorts results into Scope 1, 2 and 3; for one product, a product footprint calculator that works through its life cycle stages.
Why do two carbon calculators give different answers?
Usually because of three choices: the factor set and year, whether flights include radiative forcing, and the boundary — what is counted at all.
A calculator should show all three.
Which factors should a UK carbon calculator use?
For UK company reporting, the government’s DESNZ factors for the year the activity took place.
This calculator uses the 2026 set, for example 0.13096 kgCO2e per kWh of grid electricity.
Is the free calculator on this page accurate?
It is exact arithmetic on published factors, so its accuracy depends on your inputs and on the factor fitting your activity. It is an estimate, not a verified inventory.
Can a carbon calculator be used for SECR?
It can produce the emissions lines, but SECR also needs energy in kWh, at least one intensity ratio, a methodology statement, efficiency measures and last year’s figures in the directors’ report.
What is the difference between a carbon calculator and carbon accounting software?
A calculator takes a handful of annual figures.
Software takes feeds from meters, invoices and suppliers, keeps the evidence behind each figure, closes periods and handles Scope 3 and groups.
What does CO2e mean in a calculator result?
Carbon dioxide plus other greenhouse gases expressed as the amount of CO2 with the same warming effect.
DESNZ’s 2026 factors use 28 for methane and 265 for nitrous oxide.
Can I make a public claim from a calculator result?
Carefully.
A footprint used in a claim must be accurate, clear and complete about what it covers, under the CMA’s Green Claims Code and the CAP Code.
How do I calculate the carbon footprint of a product?
Use a product calculator that adds materials, manufacturing energy, transport and, if you go to grave, end of life — the method ISO 14067 and the GHG Protocol Product Standard describe. This site has one at /product-carbon-footprint-calculator.
Is anything stored?
No. The calculator runs in your browser.
Sources
Primary sources
Every figure, date and status on this page traces to the instrument’s owner.
Secondary commentary is never the source for a number.
Checked against 17 sources fromDepartment for Energy Security and Net ZeroGHG Protocol (WRI, WBCSD)GHG ProtocolISOIPCClegislation.gov.uk
- Department for Energy Security and Net ZeroGreenhouse gas reporting: conversion factors 2026
The UK factor set behind this calculator.
- Department for Energy Security and Net ZeroConversion factors 2026: flat file (revised July 2026)
Every row used here.
- Department for Energy Security and Net Zero2026 conversion factors methodology paper
Activity year (¶1.10), GWPs (¶1.9), electricity (Table 9).
- Department for Energy Security and Net Zero2026 conversion factors: major changes report
The electricity method change.
- Department for Energy Security and Net ZeroGovernment conversion factors for company reporting
Their purpose and earlier years.
- GHG Protocol (WRI, WBCSD)Corporate Accounting and Reporting Standard
The organisational route: boundaries, scopes and five principles.
- GHG ProtocolScope 2 Guidance
Two ways to count electricity.
- GHG ProtocolCorporate Value Chain (Scope 3) Standard
Fifteen categories beyond fuel and electricity.
- GHG ProtocolProduct Standard
The product route.
- ISOISO 14067:2018 — Carbon footprint of products
The international standard for a product footprint.
- ISOISO 14064-1 — organisation-level GHG inventories
The ISO counterpart to the Corporate Standard.
- IPCCAR6 Working Group I report
The science of CO2 equivalence.
- legislation.gov.ukSI 2008/410, Schedule 7 (SECR)
When a company must report.
- Department for Business and TradeUK SRS S2 Climate-related Disclosures (PDF)
Location-based Scope 2 required.
- Financial Conduct AuthorityPS26/19 — UK SRS reporting by listed companies
Comply or explain from 1 January 2027 periods.
- Competition and Markets AuthorityGreen Claims Code
Using a result in a public claim.
- Advertising Standards Authority (CAP)CAP Code section 11 — environmental claims
Claims in advertising.