Carbon Footprint Calculator

This calculator turns a year of home energy, driving, flying and diet into kilograms of CO2e using published emission factors, and it names every one of them in the answer. Electricity at 0.394 kg per kWh and natural gas at 5.30 kg per therm come from the EPA Greenhouse Gas Equivalencies Calculator on eGRID2022 data, heating oil and propane from the EIA carbon dioxide coefficients based on 2022 data, flights from the EPA Emission Factors for Greenhouse Gas Inventories 2025 edition, and the diet figures from Scarborough and colleagues in Climatic Change, 2014. Counted are household electricity, gas, heating oil and propane, the fuel your own car burns, the passenger-miles you flew and the production of your food. Left out are everything you buy that is not food, public transport, deliveries, water, waste, healthcare and your share of public services, so this is a household and travel footprint rather than a full consumption one.

Grid Intensity In
National and utility figures are usually published in grams. The US average is 0.394 kg per kWh, which is the same thing as 394 g per kWh.
Heating Oil and Propane In
Applies to both delivered fuels below, and to the volumes quoted back in the answer.
Driving In
Covers the distance and the fuel economy together, because the two are one measurement: mpg is a distance over a volume and litres per 100 km is the same ratio upside down.
Flights In
Applies to all three flight boxes below. The bands themselves do not move: they are the EPA haul lengths, restated in whichever unit you pick.

Fill in what you know and leave the rest at zero. Every line of the answer names the factor it used.

Straight off the bill. The US average household uses roughly 850 to 900 kWh a month.
Default is the US national average, 0.394 kg per kWh delivered, from the EPA equivalencies calculator on eGRID2022 data. Replace it with your own utility or state figure if you have one, in whichever of the two units it is quoted in.
Gas bills are usually in therms or CCF; one CCF is very close to one therm.
Total delivered over the year, in whichever unit is chosen above.
Total delivered over the year, in whichever unit is chosen above.
Distance you drive yourself, not distance you ride in someone else's car.
Read in mpg or in litres per 100 km to match the choice above, so fill it in rather than leaving the 25 there if you switched. Ignored when the distance above is zero. An electric car does not belong here: put its charging into the electricity box instead.
Add up the distances you flew, in whichever unit is chosen above. A return trip counts twice.
Most domestic flights land in this band. A return trip counts twice.
Long-haul and intercontinental. A return trip counts twice.
Daily figures for a 2,000 kcal diet from Scarborough et al. 2014.
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