Carbon Footprint Calculator
Estimate your annual CO₂ emissions from home energy use and driving. Enter your monthly electricity and gas consumption plus yearly mileage to see your total carbon footprint in pounds.
About this calculator
This calculator estimates your annual carbon dioxide (CO₂) emissions across three major sources: electricity, natural gas, and car travel. The formula is: CO₂ (lbs) = (electricity × 12 × 0.92) + (gas × 12 × 11.7) + (mileage × 0.89). The factor 0.92 lbs/kWh represents the average U.S. grid emission intensity for electricity. Each therm of natural gas produces approximately 11.7 lbs of CO₂ when burned. Driving a typical gasoline car emits roughly 0.89 lbs of CO₂ per mile. Multiplying monthly electricity and gas values by 12 converts them to an annual basis, making all three components comparable. The sum gives your estimated yearly carbon footprint, which you can compare to the U.S. average of about 36,000 lbs (16 metric tons) per person.
How to use
Suppose you use 900 kWh of electricity per month, 50 therms of natural gas per month, and drive 12,000 miles per year. Plug into the formula: CO₂ = (900 × 12 × 0.92) + (50 × 12 × 11.7) + (12,000 × 0.89). Electricity: 900 × 12 = 10,800 kWh/year × 0.92 = 9,936 lbs. Gas: 50 × 12 = 600 therms/year × 11.7 = 7,020 lbs. Driving: 12,000 × 0.89 = 10,680 lbs. Total: 9,936 + 7,020 + 10,680 = 27,636 lbs of CO₂ per year — below the U.S. average.
Frequently asked questions
What does the carbon footprint calculator measure and what units does it use?
The calculator measures your annual carbon dioxide (CO₂) emissions in pounds from three sources: home electricity, natural gas heating, and car travel. Electricity and gas inputs are monthly values that the tool annualizes automatically. The final result is expressed in pounds of CO₂, which you can divide by 2,204 to convert to metric tons. This gives you a concrete number to compare against national or global averages.
How can I reduce the carbon footprint shown by this calculator?
The biggest lever for most households is switching to renewable electricity, either through a utility green-energy plan or rooftop solar, which can cut the electricity term to near zero. Reducing car mileage by carpooling, using public transit, or switching to an electric vehicle dramatically lowers the driving component. Improving home insulation and using a programmable thermostat reduces natural gas consumption. Even modest changes — say, cutting electricity use by 20% — can eliminate hundreds of pounds of annual CO₂.
Why does the calculator use 0.92 lbs per kWh for electricity emissions?
The factor 0.92 lbs of CO₂ per kWh is a commonly used U.S. national average emission intensity for grid electricity, reflecting the current mix of coal, natural gas, nuclear, and renewables in the U.S. power grid. It is published by the U.S. EPA and EIA and is regularly updated as the grid becomes cleaner. If you live in a state with a high renewable share — like California or Washington — your actual emissions per kWh will be lower. Conversely, states heavily dependent on coal will have a higher factor. For a more precise estimate, look up your regional grid emission factor from the EPA's eGRID database.