Use this free mileage calculator to work out your fuel economy from a real trip. Enter the distance you drove and the fuel you used, and this tool shows miles per gallon, liters per 100 kilometers, and kilometers per liter in seconds — no sign-up, no account, and no personal information needed. Your numbers are calculated in your browser and are not sent to us.
Contents: Formula · How to use · Examples · Tips · FAQ · Related tools
No sign-up required. This tool works in your browser, so the amounts you enter are not stored or sent to us. For the most accurate result, use the fuel filled at the pump and the distance from your trip meter or odometer for the same trip.
Mileage Calculator Formula
The basic idea is simple: divide the distance by the fuel used. In imperial units, that gives miles per gallon. In metric units, it gives kilometers per liter, which is then converted to liters per 100 kilometers, the figure most drivers in the United Kingdom and Canada compare.
Miles per gallon (MPG) = Distance in miles ÷ Fuel in gallons
Kilometers per liter = Distance in kilometers ÷ Fuel in liters
Liters per 100 km = 100 ÷ Kilometers per liter
Liters per 100 km = 235.214 ÷ Miles per gallon
For example, 300 miles on 10 gallons gives 300 ÷ 10 = 30 miles per gallon, and 235.214 ÷ 30 = 7.84 liters per 100 km. Note that a higher MPG is better, while a lower liters-per-100-km figure is better — the two scales run in opposite directions.
How to Use the Mileage Calculator
Choose miles and gallons, or kilometers and liters, to match your car's display and your fuel receipts. Enter the distance for one trip or one tank, then enter the fuel used for that same distance — not the size of the tank. Tap Calculate Mileage, and the result shows MPG, liters per 100 km, and kilometers per liter together, so you can compare with any figure a manufacturer or a review quotes.
The most reliable method is the fill-up method: fill the tank, reset the trip meter, drive normally, then fill the tank again and note how much fuel went in and how far you drove. Do not use the dashboard estimate alone if you want a precise figure, because it is often optimistic.
Mileage Calculator Examples
Example 1 — 300 miles on 10 gallons. MPG = 300 ÷ 10 = 30.00 miles per gallon. Liters per 100 km = 235.214 ÷ 30 = 7.84. Kilometers per liter = 30 × 0.425144 = 12.75.
Example 2 — 450 kilometers on 35 liters. Kilometers per liter = 450 ÷ 35 = 12.86. Liters per 100 km = 100 ÷ 12.86 = 7.78. MPG = 12.86 × 2.35215 = 30.24.
Example 3 — 200 miles on 8 gallons. MPG = 200 ÷ 8 = 25.00 miles per gallon. Liters per 100 km = 235.214 ÷ 25 = 9.41. This car uses more fuel than the 30 MPG car in Example 1.
Mileage Calculator Tips
Fuel economy changes with driving style, traffic, hills, tire pressure, and cold weather, so compare figures from similar trips. For background on fuel economy, see Wikipedia's article on fuel economy in automobiles. Check your tire pressures, remove roof boxes and heavy loads when you do not need them, and avoid long idling — all three can improve your result on the next tank.
Mileage Calculator FAQ
What is a good MPG? It depends on the vehicle. A small gasoline car at 40 MPG is strong, a large SUV at 25 MPG may be normal, and an electric car's economy is measured differently, in miles per kilowatt-hour.
Is a higher or lower liters per 100 km better? Lower is better. It means the car uses less fuel to cover 100 kilometers.
Why does my result differ from the manufacturer's figure? Official figures are measured in test conditions. Real driving, weather, and load usually give a lower MPG than the official figure.
Can I use this tool for a partial tank? Yes, as long as the distance and the fuel match the same period. You do not need to wait for a full tank.
Does this tool store my trip data? No. It calculates in your browser and does not ask for personal information or a sign-up.
How do I convert MPG to liters per 100 km? Divide 235.214 by your MPG. For example, 30 MPG gives 235.214 ÷ 30 = 7.84 liters per 100 km.
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