Carbon Footprint Calculator
Estimate yearly household CO2e from electricity, gas, oil, driving, flights and diet using EPA 2025 and UK DESNZ 2025 emission factors, broken down by source.
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About this toolWhat is the Carbon Footprint Calculator?
The Carbon Footprint Calculator turns numbers from your bills and travel into tonnes of carbon dioxide equivalent (CO₂e) per year. Enter monthly electricity use and your grid region, yearly natural gas, heating oil or propane, up to two cars, short and long flights, and the household's typical diet. It shows the household total, the figure per person and per month, and bars showing which source is largest.
With the defaults (two people, 900 kWh of electricity a month on the US average grid, 500 therms of gas, one 28 mpg car driving 11,000 miles, two 900 mile short-haul round trips and a medium-meat diet) the total is about 14.7 tonnes a year, or 7.4 tonnes each. Food and electricity are the biggest slices, followed by driving and heating.
Every factor is visible in the page and comes from a named source, so the result can be checked rather than taken on trust. Switch to metric units for kilometres, litres and cubic metres of gas.
- Electricity, gas, oil, propane, cars, flights and diet in one place
- All 26 US eGRID subregions plus UK and custom grid factors
- Flights with or without radiative forcing, by cabin class
- Breakdown bars, per-person and per-month figures
- Sources and factors shown; runs entirely in your browser
How to use the Carbon Footprint Calculator
- Choose US or metric units and enter the number of people in the home.
- Enter average monthly electricity from a year of bills, pick your grid region (or a custom factor) and the share covered by your own solar or a certified renewable tariff.
- Enter yearly natural gas, heating oil and propane, choosing the unit on your bill.
- Add each car's yearly distance, fuel and fuel economy, then your round trips and typical one-way distance for short and long flights.
- Pick the household's typical diet, then read the total, the per-person figure and the breakdown.
Worked examples
The default two-person US household
Input
900 kWh/month (US grid), 500 therms, 11,000 mi at 28 mpg, 2 round trips of 900 mi, medium meat diet
Output
Electricity 3.80 t, heating 2.66 t, driving 3.45 t, flights 0.73 t, food 4.11 t; total 14.7 t (7.4 t each)
Driving is 11,000 / 28 = 393 gallons x 8.78 kg. Food is 5.63 kg a day x 365 x 2 people.
Same home in California with an EV and vegetarian diet
Input
CAMX grid (0.199 kg/kWh), EV at 30 kWh/100 mi, no flights, vegetarian
Output
About 8.2 t a year
The cleaner grid cuts electricity to 2.15 t, the EV adds only 0.66 t, and food drops to 2.78 t.
One transatlantic return flight
Input
5,570 km each way, economy, with radiative forcing
Output
11,140 passenger-km x 0.11704 = 1.30 t CO₂e (0.77 t without RF; 3.78 t in business class)
Business seats take more cabin space, so DESNZ allocates them nearly three times the emissions of economy.
Background and insight
Electricity uses the EPA eGRID2023 output emission rates published in the EPA GHG Emission Factors Hub (January 2025): 771.5 lb CO₂, 0.057 lb CH₄ and 0.008 lb N₂O per MWh for the US average, converted to CO₂e with the IPCC AR5 100-year warming potentials the Hub uses (28 for methane, 265 for nitrous oxide). That is 0.352 kg per kWh. The 26 eGRID subregions range from about 0.11 kg/kWh in upstate New York to over 0.6 kg/kWh in the coal-heavy Midwest and Hawaii, so picking your region matters. The UK option uses the DESNZ 2025 grid factor of 0.177 kg per kWh.
Heating fuels use the Hub's stationary combustion factors. Natural gas is 53.06 kg CO₂ per million Btu plus small CH₄ and N₂O terms, or 5.31 kg CO₂e per therm; heating oil is 10.24 kg per US gallon and propane 5.74 kg per gallon. Cars use the Hub's mobile factors of 8.78 kg CO₂ per gallon of gasoline and 10.21 kg per gallon of diesel; electric cars use your grid factor. These are combustion-only (tank-to-wheel) figures: upstream extraction, refining and transmission losses are not included.
Flights use the UK government's DESNZ 2025 conversion factors per passenger-kilometre, which already include an 8% uplift on great-circle distance for routing and holding. Economy is 0.07435 kg (short haul) and 0.06926 kg (long haul) per passenger-km for direct emissions. Because contrails and NOx add warming that CO₂ alone does not capture, DESNZ also publishes factors with a 1.7 multiplier on the CO₂ part; those "with radiative forcing" figures are the default here and can be switched off. Diet uses Scarborough et al. (2014, Climatic Change), who measured 7.19 kg CO₂e a day for high meat-eaters down to 2.89 kg for vegans on a 2,000 kcal diet.
Common use cases
Finding the biggest lever
See whether heating, driving, flying or food dominates your footprint before deciding what to change.
Comparing choices
Test the effect of an EV, a heat pump, a green tariff, fewer flights or a different diet.
School and community projects
Show students how bills turn into emissions using published government factors.
Personal climate pledges
Set a baseline in tonnes per year and track it as your energy use changes.
Tips and limitations
- Use a full year of bills; a single winter or summer month can be far from average.
- If your electricity company publishes its own emission rate, enter it as a custom factor; the eGRID regional average is a good fallback.
- Enter great-circle distances for flights (airport to airport); DESNZ factors already add 8% for routing.
- This is the part of your footprint you can measure from bills and tickets. Purchases, waste, and public services are not included, so a full life-cycle footprint would be higher.
Frequently asked questions
How much CO2 does 1 kWh of electricity produce in the US?
On EPA's eGRID2023 US average it is 771.5 lb of CO₂ per MWh, about 0.35 kg per kWh once methane and nitrous oxide are included. Your region can be half or double that, so choose your eGRID subregion.
How much CO2 does a therm of natural gas produce?
About 5.3 kg. A therm is 0.1 million Btu and EPA's factor is 53.06 kg CO₂ per million Btu, plus a little methane and nitrous oxide from combustion.
How much CO2 does a gallon of gasoline produce?
8.78 kg, according to the EPA Emission Factors Hub 2025. A car doing 28 mpg therefore emits about 0.31 kg per mile at the tailpipe.
What is radiative forcing in flight emissions?
Aircraft warm the climate through contrails and NOx as well as CO₂. DESNZ represents this with a 1.7 multiplier on the CO₂ part, which raises the economy long-haul factor from 0.069 to 0.117 kg per passenger-km. The figure is uncertain, so the tool lets you switch it off.
How much does diet change a carbon footprint?
A lot. Scarborough et al. found 7.19 kg CO₂e a day for high meat-eaters, 5.63 for medium, 3.81 for vegetarians and 2.89 for vegans. Over a year that is a difference of about 1.6 tonnes per person between high meat and vegan.
Why is my footprint lower than national averages I have seen?
National per-capita figures include industry, freight, government and the goods you buy, which this calculator does not estimate. It covers household energy, personal travel and food only.
Does solar or a green tariff count?
Enter the share of your electricity covered by your own solar or a certified renewable tariff and the electricity line is reduced by that share. That is a market-based view; your local grid still emits at its regional rate.
Is there an in-depth guide to the Carbon Footprint Calculator?
Yes. “How to Calculate Your Carbon Footprint from Your Bills” covers the background, how it works, common pitfalls and worked examples. Read the full guide.
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