Carbon Footprint Estimator
Estimate your Scope 1 and Scope 2 carbon emissions using UK DEFRA conversion factors. Designed for SMEs answering ESG questionnaires.
Your annual energy and travel data
Enter your best estimates. You can find these on your utility bills and vehicle expense records.
Check your annual electricity bill. A typical 30-person office uses 15,000–30,000 kWh/year.
Check your annual gas bill. Set to 0 if you use all-electric heating.
Estimated carbon footprint
Scope 1 (direct) and Scope 2 (electricity) emissions in tonnes of CO2 equivalent (tCO2e).
Estimated annual emissions
13.3 tCO2e
0.4 tCO2e per employee
Scope 1 (direct)
8.2 tCO2e
Gas heating + company vehicles
Scope 2 (electricity)
5.2 tCO2e
Purchased electricity
Emissions by source
Using these figures in ESG questionnaires
Most supplier ESG questionnaires ask for your Scope 1 and Scope 2 emissions. This estimator gives you a reasonable starting figure if you have not done a formal carbon audit.
Before you report these numbers
- Verify conversion factors against the latest DEFRA GHG Conversion Factors (published annually, usually in June)
- If you buy renewable electricity on a green tariff, your market-based Scope 2 figure may be lower than the location-based figure shown here
- This estimator covers Scope 1 and 2 only. Scope 3 (supply chain, commuting, business travel) is not included
- For formal reporting, consider a professional carbon audit or use the full DEFRA spreadsheet tool
Typical UK SME benchmarks: A 30-person office-based business typically produces 10–30 tCO2e/year (Scope 1+2). A manufacturing SME with on-site processes, heating, and a vehicle fleet typically produces 50–200+ tCO2e/year. Your figure depends heavily on sector, premises, and fleet size.
How we calculate this
Scope 1 = (Gas kWh × 0.183 kg/kWh) + (Car miles × fuel factor) + (Van miles × 0.373 kg/mile). All converted to tonnes.
Scope 2 = Electricity kWh × 0.207 kg/kWh (location-based UK grid average).
Conversion factors are from the UK Government’s DEFRA 2024 Greenhouse Gas Reporting guidelines. These factors are updated annually.
This is a simplified estimator covering the most common emission sources for UK SMEs. It does not include process emissions, refrigerant leakage, on-site fuel combustion, or Scope 3 categories. For comprehensive carbon accounting, use the full DEFRA reporting spreadsheet or engage a specialist.
Related guides
- How to Respond to a Supplier ESG Questionnaire
Step-by-step guide including what evidence to attach with your emissions data
- The VSME Standard Explained
VSME environment module requires Scope 1+2 emissions — this tool helps you get started
- ESG Questionnaire Response Template
Template showing how to structure your emissions data in questionnaire responses
Track your ESG data in one place
AnswerVault is being built to help UK SMEs store emissions data, evidence, and questionnaire responses in a reusable vault. Join the waitlist.