Calculate your business carbon footprint today, with the working shown

What does this carbon footprint calculator actually calculate?

It works out your business footprint for a 12-month period, following the GHG Protocol Corporate Standard on an operational control basis. That means it counts the emissions from activities your business runs day to day, sorted into the three scopes buyers and funders ask for.

Scope 1 covers fuel you burn yourself: mains gas, heating oil and LPG; red diesel, diesel, petrol or LPG for plant, machinery and generators; refrigerant top-ups for air conditioning and refrigeration; and company cars, vans and HGVs, from either fuel litres or mileage.

Scope 2 covers the electricity you buy, including EV charging. It is reported both location-based and market-based, so a REGO-backed renewable tariff or on-site solar shows up properly rather than being ignored.

Scope 3 covers the indirect sources a small firm can realistically measure: well-to-tank and transmission losses on your energy and fuel; flights by distance band and class, with radiative forcing; rail; staff mileage in their own cars, taxis and hotel nights; commuting and homeworking; waste, split by landfill and energy recovery; water supply and treatment; courier deliveries you pay for; and, if you want it, a spend-based estimate of the goods and services you buy.

It does not cover inbound freight from suppliers, the use or disposal of products you sell, investments, or supplier-specific product footprints. For most small businesses those are either small or impossible to measure fairly in year one, and the report says plainly that they are outside its boundary.

What do you need to hand?

Less than you might expect. The calculator skips anything that does not apply to you, so a freelancer at home answers far fewer questions than a café with a delivery van.

Useful things to have nearby:

• a recent electricity and gas bill, or your floor area in square metres if the landlord pays
• fuel card statements or rough annual mileage for any vehicles
• a rough count of work flights, train trips and hotel nights last year
• your bin sizes and how often they are collected
• headcount, and roughly how your team gets to work

If something is missing, carry on. The questionnaire estimates office energy from floor area using CIBSE TM46 benchmarks, waste from bin sizes using WRAP densities, and water from headcount for offices. Your answers save as you go, so you can stop to find a bill and come back to it.

How is each line of your footprint calculated?

Every line is the same simple sum: activity multiplied by a conversion factor. The factors come from the UK Government GHG Conversion Factors for Company Reporting, with the factor year matched to your reporting period.

Take electricity. Say your office used 14,000 kWh last year. The 2026 UK grid factor is roughly 0.13 kg CO2e per kWh (an approximate, rounded figure for illustration). So:

14,000 kWh × 0.13 kg CO2e per kWh = 1,820 kg CO2e, or about 1.8 tonnes.

Your report shows that working for every source, line by line in the appendix, with the exact factor used. Each line is also labelled as measured, estimate from activity data, estimate from benchmark, or data gap, so a reader can see at a glance how solid each figure is.

Why does showing the working matter?

Because the number rarely stays with you. It goes into a supplier questionnaire, a council grant form, a green loan application or a public sector tender, and someone on the other side has to decide whether to trust it.

A quick calculator that returns one unexplained total is fine for curiosity. It is much harder to defend when a procurement team asks which factors you used, whether that includes your vans, or why the figure is lower than last year. A footprint built on the GHG Protocol, using the official UK factors, with each assumption and data quality label visible, answers those questions before they are asked.

It also makes next year easier. When you swap an estimate for a real bill, you can see exactly which line changed and why.

What do you get at the end?

Your total footprint in tCO2e, split by scope and by source, plus emissions per employee and your energy use in kWh. Those are the figures most forms ask for, ready to copy across.

You also get the rest of the report as a bonus. The full ESG report covers your people, how the business is run and any targets you have, and the private action plan lists your biggest reduction opportunities, the data gaps worth closing and any policies worth adding next. If you are bidding for central government work, the footprint gives you the baseline and figures you need to complete a PPN 006 Carbon Reduction Plan. You can see how it all looks in the sample report.

How long does it take?

A sole trader working from home usually finishes in 10 to 15 minutes. An office-based SME with no vehicles takes 20 to 30, and a business with vans, or a shop, café or workshop, takes 30 to 45. Most small businesses are done in under an hour.

Your first report is free, with no card needed. Start calculating your carbon footprint and you will have a figure you can stand behind before the end of the day.