Carbon Footprint Calculator
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What Your Result Means
- Total Annual CO₂: Your estimated carbon footprint in metric tons per year from the four sources entered. The U.S. per-capita average is roughly 16 tons, so you can compare your result to that benchmark.
- CO₂ by Source: Each line shows how much a single activity contributes. Driving and air travel are typically the largest personal sources, while electricity and gas depend heavily on your region's energy mix.
- Trees Needed to Offset: A rough estimate assuming each mature tree absorbs about 22 kg (0.022 metric tons) of CO₂ per year. This is a simplification — actual sequestration varies by species, age, and climate.
How This Calculator Works
You enter annual miles driven and vehicle MPG, monthly electricity in kWh, monthly natural gas in therms, and flight activity. The tool applies EPA and IPCC emission factors to each source: 19.6 lbs CO₂ per gallon of gasoline, the national average grid intensity for electricity, 11.7 lbs CO₂ per therm for gas, and a per-passenger-mile factor for flights. Diet, consumer goods, and indirect emissions are not included.
Quick Questions
What is the average American's carbon footprint?
The U.S. per-capita average is roughly 16 metric tons of CO₂ per year, which is among the highest in the world. The global average is closer to 4–5 tons per person. Reducing driving and air travel tends to have the largest impact.
Why does this only cover four sources?
Driving, electricity, natural gas, and air travel are the four largest categories most people can directly measure and control. Diet, shopping, and supply-chain emissions are harder to quantify without detailed data, so they are excluded for simplicity.
How accurate is the tree offset number?
It is a rough ballpark. A mature deciduous tree absorbs roughly 22 kg of CO₂ per year on average, but actual rates vary widely by species, age, soil, and climate. Carbon offset programs use more precise models, so treat this number as directional.
Does switching to an EV eliminate driving emissions?
An EV eliminates tailpipe emissions, but electricity to charge it still has a carbon cost that depends on your local grid. In regions with clean grids (hydro, nuclear, renewables), the reduction is dramatic. In coal-heavy regions, the benefit is smaller but still generally positive.
Are flight emissions per person or per plane?
Per person. The factor used here (0.000255 metric tons per passenger-mile) already accounts for average aircraft load factors. A round trip doubles the distance, so enter total miles flown both ways.
Sources
- EPA — Household Carbon Footprint Calculator (emission factors for driving, electricity, and natural gas)
- EPA — Greenhouse Gas Equivalencies Calculator (tree sequestration estimates and conversion factors)
- IPCC AR6 Working Group III (global emissions context and transportation sector data)
Method & review
Estimate only. Results reflect your inputs and standard formulas. Double-check important decisions independently.