CalcLibrary

Fuel Efficiency Calculator

Calculate real-world fuel economy from distance driven and fuel used. Choose EU for L/100km, US for mpg (US), or UK for mpg (UK), then enter the numbers from a tank fill, receipt, or trip log.

km
L
Examples

500 km driven on 34 L of fuel — 6.8 L/100km.

Result
6.8 L/100km

This result falls in the calculator's middle band for the selected unit system.

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Examples

How It Works

Formula

L/100km=fuel used (L)distance (km)×100\text{L/100km} = \dfrac{\text{fuel used (L)}}{\text{distance (km)}} \times 100

MPG=distance (mi)fuel used (gal)\text{MPG} = \dfrac{\text{distance (mi)}}{\text{fuel used (gal)}}

Variables

Distance\text{Distance}

Distance driven(km or mi)

Fuel used\text{Fuel used}

Fuel consumed over that distance(L or gal)

MPG\text{MPG}

Miles per gallon for the selected US or UK gallon system

L/100km\text{L/100km}

Litres consumed per 100 kilometres(L/100km)

Choose the driving system. In EU mode, fuel economy is litres used divided by kilometres driven, multiplied by 100. In US and UK modes, fuel economy is miles driven divided by gallons used.

Frequently Asked Questions

01How is fuel efficiency calculated?
For EU mode, the calculator uses fuel used divided by distance, then multiplied by 100 to get L/100km. For US and UK modes, it divides miles driven by gallons used to get mpg.
02What is a good fuel efficiency rating?
There is no universal cutoff. Lower L/100km or higher mpg means less fuel used for the same distance. This calculator also groups results into broad built-in bands for the selected unit system.
03Does driving speed affect fuel efficiency?
This calculator only uses the distance and fuel values you enter. To compare trips, enter measurements that were recorded in the same way.
04Where did the trip fuel cost mode go?
Trip fuel cost is now a separate Driving Cost Calculator so this page can focus on measured fuel economy from distance and fuel used.
05What is the difference between US and UK gallons?
US mpg and UK mpg use different gallon units. Use the driving system switch to choose the unit that matches your fuel measurement.

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