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- Works out your car’s real gas mileage from distance and fuel used.
- Shows US mpg, L/100 km, km per liter and UK mpg.
- Works in miles and gallons or kilometers and liters.
- Adds your fuel cost per mile or km if you enter the price.
How to use the MPG calculator
Fill the tank and reset the trip meter
Then drive as usual.
Fill up again
Note the gallons or liters it takes and the distance on the trip meter.
Enter the distance and fuel used
For example 350 miles and 12.5 gallons.
Add the fuel price (optional)
To see your cost per mile or km.
How gas mileage is calculated
Miles per gallon is the distance you drove divided by the fuel you used. Measuring from one full tank to the next gives the most accurate number. In most countries outside the US, fuel economy is shown as liters per 100 km, where lower is better.
Fuel economy formulas
mpg = miles driven ÷ gallons used
L/100 km = liters used ÷ km driven × 100
L/100 km = 235.215 ÷ US mpg
Example 1: 350 miles on 12.5 gallons
At $3.50 a gallon.
- Gas mileage 28.00 mpg
- L/100 km 8.40
- km per liter 11.90
- UK mpg 33.63
- Cost per mile $0.125
Example 2: 600 km on 45 liters
Metric units.
- Fuel consumption 7.50 L/100 km
- km per liter 13.33
- US mpg 31.36
Why track your mpg
Spot problems early
A sudden drop can mean a maintenance issue.
Budget fuel costs
Know your real cost per mile.
Compare cars
Check real-world economy against the sticker.
Drive smarter
See how driving style changes mileage.
Plan a trip’s fuel budget with the fuel cost calculator, or work out per-mile costs for driving work with the gig driver cost per mile calculator.
MPG calculator FAQ
How do I calculate my mpg?
Divide the miles driven by the gallons used to refill the tank.
How do I convert mpg to L/100 km?
Divide 235.215 by the mpg. 28 mpg is about 8.40 L/100 km.
Why is UK mpg higher than US mpg?
A UK (imperial) gallon is larger, about 4.546 liters versus 3.785.
What is good gas mileage?
It depends on the car. Many modern sedans get 30 mpg or more on the highway.
Why is my mpg lower in winter?
Cold engines, winter fuel blends and heaters all use more fuel.
Is a lower L/100 km better?
Yes. It means the car uses less fuel for the same distance.