How the carbon footprint calculator works
Each activity is converted to carbon dioxide using published emission factors.
Flights ≈ Flight hours × 90 kg CO₂ per passenger-hour
Electricity = kWh × grid factor (US average ≈ 0.37 kg/kWh)
The gasoline factor is the EPA's standard figure for burning one gallon. The flight factor is an approximate average for economy seats on mixed short and long flights; per-hour emissions are higher for short trips because takeoff burns more fuel. Your grid factor depends on your region's mix of coal, gas, nuclear and renewables; the EPA's eGRID data and your utility's disclosures give local values. The tree figure uses the EPA's estimate that one urban tree seedling grown for 10 years absorbs about 0.06 t of CO₂.
Worked example
Driving 12,000 miles at 28 MPG emits 3.81 t, 10 flight hours about 0.9 t and 900 kWh a month on an average grid 4.0 t, for about 8.7 metric tons a year. Food, heating fuel, goods and services add more; the average American's total footprint is often estimated at around 14 to 16 t.
Frequently asked questions
How much CO₂ does a gallon of gas produce?
About 8.887 kg (19.6 lb), according to the EPA.
What is the average carbon footprint in the US?
Estimates vary by method, but most put the average American at about 14 to 16 metric tons of CO₂ a year.
Why does my electricity footprint depend on where I live?
Grid emissions vary from under 0.1 kg/kWh in hydro- and nuclear-heavy regions to over 0.7 in coal-heavy ones.
Do carbon offsets work?
Quality varies a lot. Reducing emissions directly is more reliable than offsetting them.
Updated October 2026. Results are estimates for education, not financial or medical advice. All math runs in your browser; nothing you type is sent anywhere.