To calculate a business carbon footprint, collect your activity data for a period (electricity and gas in kWh, fuel in litres, travel in kilometres), multiply each figure by an emission factor, and add the results in kilograms of CO₂e. Then group the totals into Scope 1, 2 and 3. A small company can get a first estimate in under an hour and a solid annual figure in a day or two.
This guide walks through the six steps in detail, with a worked example you can copy, the decisions that trip people up, and what to do with the number once you have it.
What a business carbon footprint is
A business carbon footprint is the total amount of greenhouse gases a company causes over a set period, usually a year. It is expressed in tonnes of carbon dioxide equivalent, written t CO₂e, so that carbon dioxide, methane and other gases can be added into one figure. If the unit is new to you, start with what CO₂e means.
Almost every footprint follows the same rulebook, the GHG Protocol Corporate Standard. You do not need to read all of it. The method below is that standard reduced to what a small business needs.
What you need before you start
- Twelve months of electricity and gas bills for every site.
- Fuel card statements or receipts for company vehicles.
- Travel bookings or expense reports for flights, rail and hire cars.
- Service records for air conditioning and refrigeration.
- Headcount and floor area, for the comparison figures at the end.
- A spreadsheet, or a calculator that does the multiplication for you.
Want the number without the spreadsheet? Enter four figures from your bills and get your monthly CO₂e split by scope. Open the free Business Carbon Calculator
Step 1: Set your boundary
Decide what you are measuring before you collect anything. Three decisions matter.
The period. A calendar or financial year is standard. Pick one and keep it. Your first full year becomes your base year, the reference point that later years are compared against.
The organisation. The GHG Protocol offers two approaches. Under the control approach, you count 100% of the emissions from operations you control. Under the equity share approach, you count emissions in proportion to your ownership. For a small business with no joint ventures, operational control is the simple choice: if you run it, you count it.
What is excluded. If you leave something out, say so. A common case is a shared office where electricity is included in the rent. You can estimate your share from the building’s total use and the floor area you occupy, or note it as excluded until you get the data.
Step 2: Collect your activity data
Activity data is the amount of something you used. Almost all of it is already on a bill or in your accounts.
| Source | Unit | Where to find it |
|---|---|---|
| Electricity | kWh | Electricity bills or smart meter |
| Gas or other heating fuel | kWh or litres | Gas bills, fuel delivery invoices |
| Company vehicles | Litres of fuel | Fuel cards and receipts |
| Business flights and rail | Passenger kilometres | Booking confirmations, expense reports |
| Refrigerant top-ups | kg of gas | Air conditioning service records |
Three habits make this step easier. Use physical quantities, not costs, because prices change and emissions do not follow them. Use metered readings where you can, because estimated bills hide real use. When a month is missing, fill it with the average of the months around it or the same month from the previous year, and mark it as an estimate.
Step 3: Choose emission factors
An emission factor converts an activity into emissions, for example kilograms of CO₂e per kWh. Use factors from an official source for the country where the activity happened and for the same year as your data. Electricity is the one to be careful with, because it differs several times over between countries. Our guide to emission factors explains where to find them and how to pick the right one.
Step 4: Multiply and add
The formula is the same for every line: activity data × emission factor = emissions.
Here is one month for a small company, using rounded average factors:
| Source | Activity | Factor | Emissions |
|---|---|---|---|
| Electricity | 1,200 kWh | 0.40 kg CO₂e/kWh | 480 kg |
| Gas heating | 800 kWh | 0.18 kg CO₂e/kWh | 144 kg |
| Diesel | 300 litres | 2.68 kg CO₂e/litre | 804 kg |
| Flights | 1,500 km | 0.15 kg CO₂e/km | 225 kg |
| Total | 1,653 kg (1.65 t CO₂e) |
Over twelve similar months that is about 19.8 tonnes of CO₂e a year. The electricity factor here is a generic average. Swap in the figure for your own country.
Do not skip refrigerants. The gases in air conditioning units are thousands of times more potent than carbon dioxide. If an engineer tops up a system with 2 kg of a common refrigerant with a warming potential of about 2,000, that single visit represents roughly 4 tonnes of CO₂e, more than two months of everything else in this example.
Step 5: Group the result by scope
Reports split emissions into three scopes, defined by the GHG Protocol:
- Scope 1: fuel you burn yourself and gases you leak. In the example, gas and diesel: 948 kg.
- Scope 2: electricity you buy: 480 kg.
- Scope 3: everything else in your value chain, such as flights: 225 kg.
The split matters because customers and regulators ask for the scopes separately, and because each one is reduced in a different way. Read more in Scope 1, 2 and 3 emissions explained.
Step 6: Add context, record your method and repeat
A total on its own is hard to judge. Add at least one intensity figure, which divides emissions by a measure of size. In the example, 19.8 tonnes across 12 employees is 1.65 tonnes of CO₂e per employee. If the company grows, the total may rise while the intensity falls, and both are worth knowing.
Then write down how you got the number: the period, the boundary, the source and year of each factor, and every estimate. Next year, use the same method so the two figures can be compared. If you later find a significant error or change the method, recalculate the base year as well.
How accurate does it need to be?
Accurate enough to make decisions. Spend your effort where the emissions are. If diesel is half your footprint, get the litres right to the receipt. If rail travel is one percent, a reasonable estimate is fine. Be open about which figures are measured and which are estimated. A transparent estimate is more useful, and more credible, than a precise-looking number nobody can trace.
Spreadsheet or calculator?
A spreadsheet gives you full control and a clear record, and it is all most small businesses need. One row per source per month, one column for the factor, one for the result. A calculator is faster for a first estimate and for checking your arithmetic. Many companies use both: a calculator to get started, a spreadsheet to keep the annual record.
Common mistakes
- Mixing units. Gas bills may show cubic metres as well as kWh. Use the unit your factor expects.
- Using old factors. Electricity factors change every year as the grid changes.
- Counting only electricity. For companies with vehicles, fuel is often the largest line.
- Double counting. Fuel bought on a fuel card and the same trips claimed as mileage should only be counted once.
- Forgetting refrigerants. One top-up can outweigh a month of electricity.
- Chasing perfection. A reasonable estimate now is worth more than a perfect one never finished.
What to do with the number
Use it to decide what to change. The largest line in your footprint is where action pays off first, and our list of ten ways to cut a small business carbon footprint is organised by source. If a customer or lender has asked for your emissions, see carbon reporting requirements for small businesses for what they are likely to need.
Frequently asked questions
What is a good carbon footprint for a small business?
There is no single benchmark, because a delivery firm and a design studio have very different footprints. Compare yourself with your own previous year, or use an intensity figure such as tonnes of CO₂e per employee.
Do I need to include Scope 3?
For a first footprint, Scope 1 and 2 plus business travel is a sensible start. Add more Scope 3 categories, such as commuting and purchased goods, as your data improves.
How often should I calculate it?
Once a year is the minimum for reporting. Monthly figures make it easier to spot problems and show progress.
Do employees working from home count?
Home working falls under Scope 3. It is optional in most frameworks, and small for most companies. Leave it out of a first footprint unless most of your team is remote.
How long does it take?
With a year of bills to hand, a first Scope 1 and 2 footprint for a single site usually takes a few hours. Most of that time goes on finding the data, not on the calculation.
Sources
- GHG Protocol Corporate Accounting and Reporting Standard
- UK Government conversion factors for company reporting
About the author
Georgi Todorov is an eco activist and entrepreneur. He runs Ecoki, where he builds free tools and guides that help small businesses measure and cut their carbon footprint.