Fuel Economy Converter
mpg, UK mpg, km/L and L/100km — including the reciprocal relationship people get wrong.
Fuel Economy Converter
—
Units in this category
| Unit | Symbol | Exactly |
|---|---|---|
| liters per 100 km (L/100km) | L/100km | reference unit for this category |
| US miles per gallon (mpg) | mpg | reciprocal of L/100km — 235.21 ÷ value |
| UK miles per gallon (mpgUK) | mpgUK | reciprocal of L/100km — 282.48 ÷ value |
| kilometers per liter (km/L) | km/L | reciprocal of L/100km — 100 ÷ value |
Where these factors come from
Fuel economy mixes two conventions: distance per fuel (mpg, km/L) and fuel per distance (L/100km). They are reciprocals with unit factors baked in: L/100km = 235.215 / mpg(US) and 282.481 / mpg(UK).
All 12 fuel economy pairs
| from → to | L/100km | mpg | mpgUK | km/L |
|---|---|---|---|---|
| L/100km (liters per 100 km) | — | 235.215 | 282.481 | 100 |
| mpg (US miles per gallon) | 235.215 | — | 1.20095 | 0.42514371 |
| mpgUK (UK miles per gallon) | 282.481 | 0.83267418 | — | 0.35400619 |
| km/L (kilometers per liter) | 100 | 2.352146 | 2.824809 | — |
Conversions by starting unit
liters per 100 km (L/100km)
L/100km to mpgL/100km to mpgUKL/100km to km/L
US miles per gallon (mpg)
mpg to L/100kmmpg to mpgUKmpg to km/L
UK miles per gallon (mpgUK)
mpgUK to L/100kmmpgUK to mpgmpgUK to km/L
kilometers per liter (km/L)
km/L to L/100kmkm/L to mpgkm/L to mpgUK
Common questions
Why is L/100km inverse to mpg?
mpg measures how far one gallon takes you; L/100km measures how much fuel 100 km costs. High mpg and low L/100km are both good, and the relationship is L/100km = 235.215/mpg (US).
Is UK mpg the same as US mpg?
No — the imperial gallon is 4.546 L vs the US gallon's 3.785 L, so a UK mpg figure is about 1.2× higher for the same car.
Does the conversion depend on the car?
No — it is pure arithmetic between units. Real-world consumption varies, but the conversion is exact for whatever figure you start from.