Vehicle Emissions Calculator
Calculate your car's annual CO₂ emissions in pounds based on miles driven and vehicle type. Use it to compare the environmental cost of upgrading to a more fuel-efficient car or changing driving habits.
Last updated: September 2026
Formula below · 2 sources (epa.gov, Wikipedia) · Updated Sep 2026
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About this calculator
Internal combustion engines emit approximately 19.6 lbs of CO₂ for every gallon of gasoline burned — a figure derived from the carbon content of fuel rather than engine efficiency. This calculator divides your annual miles by the vehicle type's assumed fuel economy (compact 22 mpg, sedan 25, SUV 18, pickup 15, hybrid 35) to find gallons consumed, then multiplies by 19.6. The formula is: CO₂ (lbs) = (annualMiles ÷ mpg) × 19.6. An electric car on a coal-heavy grid (about 0.3 kWh per mile at roughly 1.5 lbs CO₂/kWh ≈ 0.45 lbs per mile) is entered as the equivalent of a 44-mpg gasoline car; on the US-average grid an EV is closer to an 85-mpg equivalent. The fuel economy values are blended ratings; heavy city driving typically lowers real-world mpg by 15–30%.
How to use
Annual CO₂ = (annualMiles ÷ vehicle mpg) × 19.6 lbs of CO₂ per gallon of gasoline. For 12,000 miles at 25 mpg: 12,000 ÷ 25 = 480 gallons → 480 × 19.6 = 9,408 lbs of CO₂ per year (about 4.3 metric tons). Driving fewer miles or choosing a higher-mpg vehicle lowers emissions proportionally; an all-electric vehicle on a clean grid approaches zero tailpipe CO₂.
Frequently asked questions
How many pounds of CO₂ does a car emit per mile driven?
It depends on fuel economy. A sedan averaging 28 mpg emits about 19.6 ÷ 28 ≈ 0.70 lbs of CO₂ per mile, while a truck at 18 mpg emits roughly 1.09 lbs per mile. The 19.6 lbs-per-gallon figure is a physical constant based on the carbon content of gasoline set by the U.S. EPA. Over 12,000 miles, that difference adds up to thousands of pounds of CO₂ annually. Choosing a higher-mpg vehicle is one of the single largest personal emissions reductions available.
Why does city driving increase vehicle carbon emissions compared to highway driving?
Frequent acceleration and braking in city traffic burns more fuel per mile than steady highway cruising, where engines operate near their efficiency sweet spot. Idling at stoplights also consumes fuel while producing zero forward progress. Most vehicles achieve 15–30% worse fuel economy in city conditions versus highway. This calculator uses a blended mpg, so if you drive 80% city miles, your real-world emissions will be higher than the stated highway rating suggests. Hybrids partially recover braking energy, which is why they perform proportionally better in city conditions.
How does my vehicle's CO₂ output compare to the average American car?
The average new passenger car sold in the U.S. emits roughly 4.6 metric tons (about 10,100 lbs) of CO₂ per year, based on EPA data for ~15,000 annual miles. An SUV driven 15,000 miles at 20 mpg produces approximately 14,700 lbs — well above average. A fuel-efficient sedan driven 10,000 miles might emit only 7,000 lbs. Transportation accounts for the largest share of U.S. greenhouse gas emissions (~29%), making vehicle choice one of the most impactful personal climate decisions. Electric vehicles shift emissions to the power grid, often achieving the equivalent of 80–100+ mpg.
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