Carbon Footprint Calculator
Estimate your yearly carbon emissions from driving, home energy, flights and diet.
About the Carbon Footprint Calculator
Factors: petrol 8,887 g CO₂ per US gallon and natural gas 5.3 kg CO₂ per therm (US EPA); US average delivered electricity 0.394 kg CO₂ per kWh (EPA eGRID, change it for your grid); flights use EPA 2025 per-passenger-mile factors with typical distances of 700 and 4,000 miles each way.
Diet emissions are average UK diets from Scarborough et al. (Climatic Change, 2014), from 7.2 kg CO₂e a day for high-meat diets to 2.9 kg for vegan diets.
The formula
Total = Σ activity × emission factor
Worked example
Example: Yearly footprint = 15.07 t CO₂e
- Inputs: Car distance per year: 12,000 miles or km; Distance in: miles; Car fuel economy (US mpg): 31 mpg; Electricity per month: 990 kWh; Grid emissions: 0.43 kg CO₂/kWh; Natural gas per month: 44 therms; Short/medium flights per year (return): 2; Long-haul flights per year (return): 1; Diet: Medium meat (50–99 g/day).
- Formula: Total = Σ activity × emission factor
- Result: Yearly footprint = 15.07 t CO₂e
Things to keep in mind
- A simplified household estimate; it leaves out goods, services and public infrastructure, which add several tonnes per person in rich countries.
Questions people ask
What's the biggest lever?
Usually driving, flying, home heating and diet, in that order for many households.
Do offsets cancel emissions?
Quality varies widely; reducing emissions first is more reliable.