CO2 Per Gallon of Gas: A Simple, Sourced Way to Estimate Emissions

What We Know (Sourced)

EPA provides a standard emissions factor for gasoline: 8,887 grams of CO2 per gallon of gasoline burned. The U.S. Energy Information Administration (EIA) provides a closely aligned coefficient (8.89 kg CO2 per gallon) in its carbon dioxide emissions coefficient documentation.

FuelEconomy.gov provides tools and guidance for comparing vehicles and includes a "Beyond Tailpipe" calculator for looking at upstream + tailpipe emissions boundaries when you want a broader accounting.

The Two-Step Formula (Miles → Gallons → CO2)

Step 1: Convert miles and MPG into gallons used.

Step 2: Convert gallons into CO2 using the EPA factor.

If you prefer kilograms:

• 8,887 g = 8.887 kg CO2 per gallon (unit conversion).

Related fuel-cost math: cost per mile and cost to drive 1,000 miles.

Worked Examples

Example A: 300 miles at 30 MPG.

• Gallons used = 300 ÷ 30 = 10 gallons
• CO2 = 10 × 8,887 g = 88,870 g = 88.87 kg

Example B: Commute budgeting (weekly).

• Start with weekly miles and your real MPG
• Compute weekly gallons
• Multiply by 8,887 g/gal

Related: commute cost and carpool savings (cost and CO2).

What This Estimate Does and Doesn't Include

This factor estimates tailpipe CO2 from burning gasoline. It does not include upstream emissions from producing and distributing gasoline.

If you want an upstream + tailpipe boundary, FuelEconomy.gov provides a Beyond Tailpipe calculator and explains upstream emissions concepts.

What's Next

• Use your own data: log gallons from receipts for the most direct estimate.
• Compare scenarios: model CO2 for two MPG values (for example, after a maintenance fix). Related: maintenance checklist.
• If comparing across fuels: use tools that define upstream boundaries, such as FuelEconomy.gov's Beyond Tailpipe calculator.

Frequently Asked Questions