MPG Calculator

What is mpg calculator?

Fuel economy tells you how far a vehicle travels on a given amount of fuel. Countries report it in different ways: miles per gallon in the United States and United Kingdom, and liters per 100 kilometers in much of Europe and Asia.

Checking your own figures from a full tank to full tank is the most honest way to see real world economy, since the label figure is measured in standard test conditions.

How to use the mpg calculator

1. Fill the tank and note the trip meter or odometer.
2. Drive normally, refill and enter the distance and the fuel added.
3. Optionally enter the price per unit to see the cost per distance.

How the mpg calculator works

Distance is converted to kilometers and fuel to liters. Miles per US gallon equals miles divided by US gallons, and one US gallon is 3.785411784 liters. A UK gallon is 4.54609 liters. Liters per 100 km equals liters divided by kilometers, times 100.

Worked example

Common uses of the mpg calculator

• Tracking real fuel economy.
• Comparing two vehicles.
• Estimating trip cost.
• Checking if a fault is hurting economy.
• Converting between MPG and L per 100 km.

Tips and common mistakes

Use the same pump or fill to the click each time for a fair comparison.

Average several tanks, because one fill can be off by a few percent.

US and UK MPG are different. A UK gallon is about 20 percent bigger.

Background: what to know before you rely on it

Fuel economy is shaped by speed, tyre pressure, load, temperature, traffic and driving style. Official ratings come from standard laboratory test cycles, so everyday figures are often lower. The inverse measure used in much of the world, liters per 100 kilometers, is useful because it rises directly with fuel use, which makes savings easier to compare. Going from 20 to 25 MPG saves more fuel per mile than going from 40 to 45 MPG, a fact that is clearer in liters per 100 km.

Private, free and fast

This tool runs entirely in your browser. What you type or choose is not uploaded to a server and is not saved after you close the page, which keeps it fast and private. It is free to use as often as you like. See more in all calculators, or browse the full list of tools.

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Results are for information and education. For legal, financial, medical or security decisions, check with a qualified professional. Financial results are estimates and exclude fees and taxes unless the tool says otherwise.