Gas mileage calculator

Fuel economy in miles per gallon = miles traveled divided by gallons used.

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Miles traveled

Gallons used

More inputs and assumptions

Input mode

Answer

…

Miles/gallon = distance/fuel. In metric mode, km/L = kilometres/litres and L/100 km = 100 × litres/kilometres. Modes label the entered quantities; they do not convert gallon definitions.

More results

Precision and calculation record

Decimal places in numeric results and text downloads

Rounding changes displayed numbers, not the calculation. Text, fractions, matrices and CSV schedules keep their own formatting. Automatic keeps up to 12 significant digits, with money shown to cents where applicable.

Saved scenario

Save the current answer, then change an input to compare. This clears when you leave.

Formula and assumptions

Use a consistent fill-to-fill interval. This does not convert US and imperial gallons; the result follows the gallon unit you enter.

Automatic precision shows numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.

Scratch calculator

Check another calculation

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Updated 2026-09-26

Using Gas mileage calculator

Miles/gallon = distance/fuel. In metric mode, km/L = kilometres/litres and L/100 km = 100 × litres/kilometres. Modes label the entered quantities; they do not convert gallon definitions.

Use a consistent fill-to-fill interval. This does not convert US and imperial gallons; the result follows the gallon unit you enter.

Next: Basic calculator

A worked example

With miles traveled = 300, gallons used = 10, the miles per gallon is 30.

Before you use the result

Use a consistent fill-to-fill interval. This does not convert US and imperial gallons; the result follows the gallon unit you enter.

Example results for miles traveled

These examples use Gallons used: 10; Input mode: Miles and gallons. They are reference calculations, not recommended settings.

Miles traveled	Miles per gallon
150	15
300	30
600	60

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ToolOctopus. “Gas mileage calculator.” Updated 2026-09-26. https://tooloctopus.com/gas-mileage-calculator.

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