RPMBase

Fuel economy from one fill-up or one trip

Enter how far you drove and how much fuel you used. The result is arithmetic, not a reading from your car. For a running log, keep fill-ups in the fuel tracker.

This page answers one question: given a distance and a volume of fuel, what was the economy. It does not read your trip computer, and it does not remember the last tank.

Use it after a full-to-full fill-up, or after a trip where you know both numbers. Partial tanks and mixed units make the result look precise when it is not. If you want a trend, log fill-ups instead of repeating this calculator.

RPMBase on the phone is the running log. This tool is the arithmetic you can do before that log exists.

Distance unit
Fuel used

US gallons and UK gallons are different sizes. Both mpg figures are shown so you can match the unit you see on a pump or a spec sheet.

Estimates for general information only, not professional or legal advice. Check your owner's manual, a qualified mechanic and current official rules before relying on a result.

Example

You drove 480 km between two full tanks and put in 36 liters. That is 36 ÷ 480 × 100 = 7.5 L/100 km, about 13.3 km per liter, and about 31.4 US mpg.

If the second fill-up was not to full, treat the result as a rough check only. Log several honest fill-ups in the fuel tracker for a trend.

Get RPMBase

Questions

Is one fill-up enough?Show

It is enough for that interval. It is a weak picture of the car. Highway, idle, and a half tank all move the number. Several full tanks in a row are the habit that matters.

Which mpg figure should I use?Show

Use US mpg if the pump or the spec sheet is US gallons. Use UK mpg only when the source is imperial gallons. Liters per 100 km avoids that mix-up.

Does this save my numbers?Show

No. Nothing is stored when you leave the page. The fuel tracker in the app is where fill-ups stay on the car.

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