How do you calculate fuel mileage?

Mileage between two fill-ups equals the distance you drove since the last fill divided by the litres you added. In km/L: km ÷ litres. In MPG (US): miles ÷ US gallons. In L/100km: (litres ÷ km) × 100.

What's the difference between km/L, MPG and L/100km?

km/L and MPG describe how far you go per unit of fuel — higher is better. L/100km describes how much fuel you use per fixed distance — lower is better. 20 km/L ≈ 47 US MPG ≈ 5.0 L/100km.

What is cost per kilometre?

Cost per km = (price you paid for the fill) ÷ (kilometres that fill covered). It's the cleanest measure of running cost — better than 'price per litre' because it accounts for how efficiently your vehicle uses that fuel.

Why is the trip-meter delta used instead of the odometer?

Recording the kilometres since your last fill (the trip-meter delta) is the smallest, easiest number to remember at the pump. Recording an absolute odometer means you have to remember the previous reading, and a typo of a single digit ruins the math. FuelNote uses the trip-meter delta everywhere.

Free mileage calculator.

Compute fuel mileage in km/L, MPG and L/100km — plus cost-per-kilometre — from one fill-up. No sign-up. No tracking. Works for petrol, diesel, cars, bikes and scooters.

We don't store anything. The math runs on your device.

Want this happening automatically for every fill-up? Open FuelNote.

How to calculate fuel mileage

Four numbers, one tank.

To calculate fuel mileage, you need two numbers from the same fill-up: the distance you drove since the last fill, and the amount of fuel you added to bring the tank back to full. From those:

km/L = kilometres ÷ litres added. Higher is better.
MPG (US) = miles ÷ US gallons. Higher is better.
L/100km = (litres ÷ kilometres) × 100. Lower is better.

If you also enter the total price you paid, the calculator gives cost-per-kilometre — the number you should actually budget against, because it folds your vehicle's efficiency and the current fuel price into a single value.

One reading is a snapshot. A 30-day rolling average across many fill-ups is a trend. FuelNote does that part for you.

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Free mileage calculator.

Four numbers, one tank.

Stop fighting the spreadsheet. Start logging in five.

Stop fighting the spreadsheet.
Start logging in five.