How to calculate your small business carbon footprint

Your small business carbon footprint is the total greenhouse gas your business causes over a year, expressed in tonnes of CO2e. To calculate it, you take each activity (kWh of electricity, litres of diesel, kilometres by train) and multiply it by the matching UK government conversion factor, then add the results together. For many small UK firms the answer is somewhere between one and a few dozen tonnes.

That sounds like consultant territory. It isn’t. If you can find an energy bill and remember roughly how often you travelled for work last year, you already have most of what you need.

Why are you being asked for a carbon footprint?

Usually because someone else needs it. A large customer is counting the emissions in its supply chain and has sent you a form. A council grant application wants your current emissions in tonnes. A bank’s green loan form asks for a baseline. A bid for a major government contract needs a Carbon Reduction Plan.

None of these people expect a perfect number. They want a sensible figure, a method they can follow and some honesty about what was estimated. That is a much lower bar than most business owners assume, and you can clear it in an afternoon.

What goes into a small business carbon footprint?

Carbon accounting sorts emissions into three groups, defined by the GHG Protocol Corporate Standard. Our guide to Scope 1, 2 and 3 emissions covers them properly, but in short:

• Scope 1 is fuel you burn yourself: gas for heating, and petrol or diesel in vehicles the business owns or leases.
• Scope 2 is the electricity you buy, including electricity used to charge company electric vehicles.
• Scope 3 is everything else connected to your business: flights and trains, waste, water, the things you buy, how staff get to work.

For an office-based business, the sources that matter most, and that you can realistically measure, are electricity, heating, vehicles and business travel. Waste and water are usually small but quick to include, and buyers like seeing them there.

How do you calculate it, step by step?

1. Pick a reporting period. Twelve months is standard. Your financial year works perfectly well.
2. Gather your activity data. kWh from electricity and gas bills, fuel receipts or mileage for each vehicle, the number of flights and train journeys, bin sizes and collection days, water bills if you have them.
3. Fill gaps with sensible estimates. If the landlord pays the energy bills, estimate from floor area. If there is no water meter, estimate from headcount. Write down every assumption.
4. Multiply by conversion factors. Use the UK government conversion factors, still widely known as the DEFRA factors, for the year that matches your reporting period.
5. Add it up and convert to tonnes. The factors give kilograms of CO2e, so divide the total by 1,000 to get tCO2e.
6. Record your method. Note which figures came from bills and which were estimated. This is what makes the number believable to whoever reads it.

A worked example: a six-person design agency

Take a six-person agency renting a small office with its own meters. It used 9,000 kWh of electricity and 12,000 kWh of gas last year. The team took 20 return train trips of about 200 miles each way and two short-haul return flights to client meetings in Europe. It has one 240 litre general waste bin collected weekly.

The factors below are rounded from the 2026 UK government set and are approximate. Your own numbers will differ.

Source	Activity	Approximate factor	Emissions
Gas heating (Scope 1)	12,000 kWh	0.182 kg per kWh	2.19 t
Electricity (Scope 2)	9,000 kWh	0.131 kg per kWh	1.18 t
Flights (Scope 3)	2 short-haul economy returns, about 5,900 km	0.126 kg per passenger km	0.74 t
General waste (Scope 3)	About 1 tonne a year to landfill	about 520 kg per tonne	0.54 t
Rail (Scope 3)	8,000 miles, about 12,900 km	0.031 kg per passenger km	0.40 t
Water (Scope 3)	About 56 cubic metres	about 0.36 kg per cubic metre	0.02 t
Total			about 5.1 tCO2e

A few things jump out. Heating is the biggest single source, which is typical for a gas-heated office. Two flights produced nearly twice the emissions of twenty train journeys. And the whole business comes in at under a tonne per person, which is a useful figure to quote when a customer asks for an intensity measure.

There’s also a quick win hiding in the waste line. That figure assumes landfill. If the waste contractor sends general waste to energy recovery instead, the factor drops to under 5 kg per tonne and the line almost disappears. One email to the contractor could change it.

What if you don’t have the figures?

This is the most common worry, and it rarely stops anyone. Standard benchmarks exist for most gaps:

• Office energy from floor area. The CIBSE TM46 benchmark for a general office is about 95 kWh of electricity and 120 kWh of heating per square metre per year. Our guide to office carbon footprints shows this in action.
• Co-working share from desks and days. If you rent desks, your share of the building can be estimated from the number of desks and how many days a week you use them. See how to account for a co-working desk.
• Waste from bin sizes. Bin volume, number of bins and collections per week, converted to tonnes using published WRAP densities.
• Water from headcount. The CIRIA C657 benchmark puts typical office water use at about 9.3 cubic metres per employee per year.

Estimated numbers are perfectly acceptable as long as they are labelled. Next year, swap the estimate for a real bill and your footprint gets more accurate without any extra effort.

How long will yours take?

Pick the option that sounds most like your business. You will see a realistic time, what to have nearby and a head start on the questions.

Which sounds most like you?

Sole trader working from homeConsultants, designers, developers, coaches10 to 15 minSole trader or freelancer in a co-working spaceA desk at a WeWork, Regus or local hub10 to 15 minSmall team in a co-working or serviced officeStartups and agencies with 2 to 25 people15 to 20 minSME with its own office and no vehiclesProfessional services, tech firms, studios20 to 30 minSME with vans, cars or regular staff travelTrades, field services, consultancies on the road30 to 45 minShop, cafe, workshop or product businessRetail, hospitality, makers and manufacturers30 to 45 min

Your estimate

Pick the option closest to your business and we will tell you how long it takes and what to have ready.

Most small businesses finish in under 30 minutes. Sole traders are often done in 10.

What does the ESG Now footprint include, and what does it leave out?

The ESG Now questionnaire calculates the sources a small business controls directly and that buyers ask about first: heating fuels, company vehicles, plant fuel and refrigerant leaks (Scope 1), purchased electricity and EV charging (Scope 2), and water, waste, courier deliveries, flights, rail, mileage claims in employees’ own cars, taxis and hotels (Scope 3). It reports Scope 2 both location-based and market-based, includes radiative forcing for flights, and labels every figure as measured, estimated or a data gap.

It also estimates staff commuting and working from home, and can add an optional spend-based estimate of the goods and services you buy. These are rougher figures and are labelled as estimates. It does not cover inbound freight paid for by your suppliers or the use and disposal of products you sell. If you want to understand or check the commuting, homeworking and travel figures, our guides on working-from-home emissions and business travel emissions show the methods.

What should you do with the number once you have it?

Treat your first footprint as a baseline. It’s the figure everything else is measured against, so keep the method and the assumptions alongside it.

From there, the useful next steps are:

• Answer the request that started this. Most supplier forms and grant applications want a total in tonnes, a split by scope and a line on your method.
• Pick one or two reductions. Heating controls, a renewable tariff or a rail-first travel policy are realistic places to start.
• Repeat it next year. The second footprint is where you can show progress, and it takes a fraction of the time.
• Use it for tenders. If you’re bidding for central government work, you’ll need a Carbon Reduction Plan. ESG Now does not produce the PPN 006 document itself, but it gives you the carbon footprint, baseline and figures you need to complete the official template.

If you want the whole thing done for you, start the free questionnaire. Most small businesses finish in under 30 minutes, and you’ll come away with a full ESG report, your carbon footprint and an action plan. Our carbon footprint calculator page shows exactly what it calculates and what you need to hand. There is more on who it suits on our small businesses page.