Gas Mileage Calculator
Work out your car's real MPG from a fill-up, budget a road trip's fuel cost per person, or compare a hybrid with a gas car — free, no account, nothing leaves your browser.
Quick MPG check
Your fuel economy
- 30mpg
- 36.03mpg
- 12.75km/L
- 7.84L/100km
300 miles ÷ 10 gal (US) = 30 US mpg
Same trip in metric terms: 7.84 L/100km. All four figures are the same trip expressed in different units.
Plan a trip's fuel cost
Heading out with friends? Enter the distance, your car's fuel economy and the current fuel price to get the total and the per-person share.
Open the trip cost calculatorHybrid vs gas, fuel-only math
See what a hybrid's better economy is worth in fuel money at your annual mileage — fuel cost only, no purchase-price claims.
Compare hybrid vs gas costFrequently asked questions
- How do I calculate my car's gas mileage?
- Fill your tank, note the odometer, drive, then fill again. Divide the miles driven by the gallons you pumped on the second fill. For example, 300 miles on 10 gallons is 30 mpg.
- How is trip fuel cost calculated?
- Trip cost = (trip distance ÷ your car's mpg) × fuel price. If 4 people share the ride, divide the total by 4 for the per-person cost — the trip cost calculator above does both.
- Why do US mpg and UK mpg show different numbers?
- A US gallon is about 3.785 liters while a UK (imperial) gallon is about 4.546 liters, so the same car shows a higher mpg number in the UK scale. Both are shown here from the same fill-up data.
- Do you store or send my data anywhere?
- No. Calculations run in your browser. Saved cars are kept in your browser's localStorage only, and there is no account or server.