Fuel Economy Converter

This free fuel economy converter converts between US MPG, imperial MPG, kilometres per litre, miles per litre, litres per 100 km and gallons per 100 miles (US and imperial). Enter one value and every equivalent updates instantly in the "All units" table, so you never need to convert twice.

Fuel economy comes in two flavours. Efficiency units like MPG and km/L measure distance travelled per unit of fuel — bigger is better. Consumption units like L/100km and gal/100 mi measure fuel burned over a fixed distance — smaller is better. Because these are reciprocals of each other, converting between them needs inverse maths, not a simple multiply; this tool handles that correctly. Choose the number of decimal places, swap the two units, or copy the result with one click.

Note the US and imperial gallon differ: an imperial gallon is about 20% larger (4.546 L vs 3.785 L), so 40 MPG (imperial) is a lower real economy than 40 MPG (US). This converter uses the exact 1 mile = 1.609344 km and precise gallon definitions.