Home Carbon Footprint Calculator

Your home carbon footprint measures the total CO2 (and equivalent greenhouse gases) produced by your household each year from three major sources: electricity use, home heating, and personal car travel.

Why this calculator asks for energy, not money An earlier version of this page took your bills in dollars and converted them to energy using fixed prices. That approach cannot work. Fuel prices vary by country, by state, by supplier and by year, so any built-in price is wrong for most readers and goes stale for the rest. Carbon comes from fuel burned, and the amount of fuel is printed on your bill. Enter that and the answer does not depend on what you paid for it.

Electricity Your bill states kilowatt-hours used. A typical US household runs 850 to 1,000 kWh a month, though a large all-electric home can double that. Generating 1 kWh from the US average grid mix produces about 0.386 kg of CO2, so the monthly figure is kWh × 0.386, and × 12 for the year. If your grid is cleaner than the US average this overstates you, and the difference is not marginal: France sits near 0.06 kg per kWh, while coal-heavy grids exceed 0.7.

Home Heating Pick the unit your supplier bills in and enter the quantity, not the cost. The emission factors are combustion chemistry and do not change with price:

Heating is seasonal, so use an average month rather than a January one, or divide your annual usage by twelve. Oil and propane are usually delivered a few times a year, which makes the annual-divided-by-twelve route the easy one. Electric heating is already inside the kWh figure above, so selecting it here adds nothing rather than double-counting.

Car Travel Fuel type matters enormously. A gasoline car emits approximately 0.404 kg of CO2 per mile (0.251 kg/km). Diesel is slightly higher at 0.450 kg/mile. A hybrid cuts that to around 0.200 kg/mile. An electric vehicle powered by the average US grid produces about 0.120 kg per mile, which is not zero but is roughly 70% lower than a gasoline car.

Understanding Your Result The US average personal carbon footprint is about 16 tonnes of CO2 per year, one of the highest in the world. The EU average is around 7 tonnes. The global target to limit warming to 1.5°C is approximately 2 tonnes per person per year.

One tree absorbs roughly 22 kg of CO2 per year. This calculator tells you how many trees would need to grow for a full year to absorb your footprint, which is a vivid way to put the numbers in perspective.

Worked Example 900 kWh of electricity a month, 55 therms of gas a month, and 12,000 miles a year in a gasoline car:

• Electricity: 900 × 0.386 × 12 = 4,169 kg
• Gas heating: 55 × 5.30 × 12 = 3,498 kg
• Car: 12,000 × 0.404 = 4,848 kg
• Total: 12,515 kg, or 12.5 tonnes a year

That sits below the US average of 16 tonnes and well above the 2-tonne global target, which is the position most Western households find themselves in. Notice how evenly the three split. There is no single lever here that fixes the total, which is the honest and slightly deflating answer: cutting driving to zero still leaves you at 7.7 tonnes.