MPG Calculator
Work out your car's miles per gallon from two odometer readings and the gallons you put in, plus cost per mile. Then estimate a trip's fuel cost, convert between US mpg and L/100 km, and compare what two cars cost in gas each year.
MPG calculator
Gas mileage calculator: trip fuel cost
Fuel economy calculator: convert mpg and L/100 km
Fuel consumption calculator: compare two cars
How to calculate mpg
Fill the tank, reset the trip meter (or note the odometer), drive, then refill. MPG = miles driven ÷ gallons used to refill. 342 miles on 11.4 gallons is 30.0 mpg. Average several tankfuls for a reliable figure.
- US vs UK mpg: a US gallon is 3.785 liters and an imperial (UK) gallon is 4.546 liters, so the same car shows about 20% higher mpg in UK figures. This page uses US gallons.
- L/100 km is the inverse measure used in most other countries: L/100 km = 235.21 ÷ US mpg. Lower is better.
- The EPA's official ratings for any car since 1984 are on FuelEconomy.gov, the joint site of the Department of Energy and the EPA.
Common questions
How do I calculate my gas mileage?
Divide the miles you drove by the gallons it took to refill the tank. 300 miles ÷ 10 gallons = 30 mpg.
How do I convert mpg to L/100 km?
Divide 235.21 by the US mpg figure. 30 mpg = 7.84 L/100 km.
How much gas will a trip use?
Divide the distance by your mpg. A 400-mile trip at 28 mpg uses about 14.3 gallons.
Why is UK mpg higher than US mpg?
The imperial gallon is about 20% larger than the US gallon (4.546 vs 3.785 liters).
What is good gas mileage?
It depends on the vehicle class. Compare your car with its EPA rating on FuelEconomy.gov.
Sources
Related
General information, not financial, tax or legal advice. Check important numbers with the official source before acting on them.