How to calculate your company’s carbon footprint: a step-by-step guide
Calculating your company’s carbon footprint comes down to four steps: define what to include, collect your activity data, multiply it by the right emission factors, and total the result across Scope 1, 2 and 3. This guide walks through each step in plain language for small and mid-sized businesses.
1. Set your boundary and reporting period
Decide which sites, entities and activities you will include (your "organisational boundary") and the 12-month period you are reporting. A clear, consistent boundary is what makes your footprint comparable year on year.
2. Gather your activity data
Collect the underlying activity figures for the period. The most common sources for SMEs are:
- Electricity and gas bills (kWh)
- Fuel records for vehicles and generators (litres)
- Business travel (distance flown / driven)
- Waste and water records
- Spend on purchased goods and services (for Scope 3)
3. Apply emission factors
Multiply each activity figure by its emission factor (kg CO₂e per unit) to convert it into emissions. Use a location-specific factor for electricity, and source-cited factors for fuels and travel. Then group the results into Scope 1 (direct), Scope 2 (purchased energy) and Scope 3 (value chain).
4. Total, review and report
Add everything up, sanity-check for spikes or gaps, and keep your supporting evidence (bills, calculations) for assurance. From there you can report against a framework such as VSME and set reduction targets.
Frequently asked questions
What data do I need to calculate a carbon footprint?
At minimum, your energy bills (electricity and gas), fuel use, and business travel. For Scope 3 you also need data on purchased goods, waste and other value-chain activities — often estimated from spend at first.
How long does it take to calculate a footprint?
A first Scope 1 and 2 estimate can take a few hours once you have your bills. Scope 3 takes longer because it spans the value chain. Software that auto-extracts data and applies factors can cut this to minutes.