Mileage calculator
Find your actual fuel economy from a fill-up, in whichever unit you're used to.
Fill in the fields and press Calculate to see your result here.
How this calculation works
Miles per gallon is distance ÷ gallons used. Liters per 100 km is (liters used ÷ distance) × 100 — a lower number means better economy, the opposite direction from mpg. Kilometers per liter is simply distance ÷ liters.
Worked example
You drive 350 miles and use 14 gallons of fuel: 350 ÷ 14 = 25 mpg. In metric terms, using 48 litres over 600 km gives 48 ÷ 600 × 100 = 8.0 L/100km.
Tips
Fill up completely both times for an accurate reading
The most reliable way to measure real mileage is to fill the tank completely, reset the trip meter, drive normally, then fill up completely again — the second fill-up amount is your fuel used.
Average over several tanks
One fill-up can be skewed by pump cut-offs or a long idle. Averaging a few tanks gives a steadier number.
Lower or higher is better?
For L/100 km a lower number is better. For mpg and km per litre a higher number is better.
Small habits matter
Tyre pressure, speed, roof racks and heavy loads all affect fuel economy.
Frequently asked questions
Why does a lower number mean better economy in L/100km but not mpg?
They measure opposite things: mpg is distance per unit of fuel (higher is better), while L/100km is fuel per unit of distance (lower is better).
What's a good MPG for a car?
It depends heavily on the vehicle: a small hatchback might average 35–45 mpg, a typical mid-size sedan 25–35 mpg, and a large SUV or truck 15–22 mpg. Hybrids and EVs are a different story entirely, so compare against similar vehicle types rather than a single target number.
Does this convert between mpg and L/100km for me?
Enter your figures in whichever unit you measured them in — this calculator works out the result in that same system. For converting an existing mpg or L/100km figure into the other unit directly, the unit converter is the better tool.