Gas Mileage Calculator

Divide the miles driven by the gallons of fuel used. Driving 300 miles on 12 gallons gives 300 / 12 = 25 miles per gallon. In metric mode the tool converts your kilometres and litres to miles and gallons first, then does the same division.

They are inverse measures, so a higher MPG means a lower L/100km. This tool converts your figures to litres and kilometres, divides litres by kilometres and multiplies by 100. At 300 miles on 12 gallons that works out to 9.41 L/100km.

Yes. Flip the toggle to Metric and enter kilometres and litres instead of miles and gallons. The tool still reports MPG, L/100km and km/L, using 1 mile = 1.609344 km and 1 US gallon = 3.785411784 litres.

US gallons. The conversion uses 1 US gallon = 3.785411784 litres. An imperial gallon is larger at about 4.546 litres, so if you filled up with imperial gallons your MPG figure here will read low.

Total fuel cost equals the fuel used times the price you enter. Cost per mile is that total divided by the miles driven, so a $42 fill over 300 miles is $0.140 per mile. In metric mode the price is treated as a per-litre price.

No. Distance and fuel are the only required fields. Leave the price blank and you still get MPG, L/100km and km/L; the total cost and cost per mile stay empty until you add a valid price.

MPG, L/100km, km/L and total cost are shown to two decimal places, while cost per mile is shown to three so small trips read clearly. The engine itself keeps full precision, so rounding only affects the display.

City driving, cold starts, idling, cargo, terrain and speed all lower economy. Measuring your own fill-ups, as this tool does, gives a truer figure than the rated number, especially if you track several tanks.

Yes. The calculation runs in your browser and nothing is sent to a server, so your distances, fuel and prices never leave your device.