Fuel Economy Converter

MPG (miles per gallon) has been the US fuel-economy metric since the 1910s; US EPA standardized the testing procedure in 1975 following the 1973 oil crisis. The 2008 5-cycle revision (adding cold start, air conditioning, and higher-speed tests) brought EPA MPG ratings closer to real-world observations, with "city" and "highway" labels most drivers see in the window sticker.

L/100 km (liters per 100 kilometers) — the European standard since the 1950s — is the inverse of MPG: lower numbers mean more efficient. This flipped convention makes sense once you notice that the linear quantity is fuel consumed, not distance traveled. The MPG-vs-L/100km mental-math trick: 235.215 / MPG ≈ L/100 km. 30 MPG = 7.84 L/100 km.

The US-vs-UK gallon confusion runs deep: US gallon = 3.785 L, Imperial (UK/Canadian) gallon = 4.546 L — a 20% difference. British car magazines have always quoted MPG in imperial gallons, giving the misleading impression that UK cars are much more efficient than US equivalents. Australian MPG is the imperial one, but Australia switched to L/100 km in 1974. Canada phased out imperial gallons in 1979 but still sells fuel in litres and imperial-pint beer.

Enter a value in any field; all others update automatically. Covers the four common fuel-economy units: MPG (US), MPG (Imperial/UK), L/100 km, and km/L. Because MPG and L/100 km are reciprocal scales (one is distance/fuel, the other fuel/distance), direct subtraction isn't meaningful — always convert to a single unit before comparing.

Quick benchmarks: 30 MPG (US) = 36 MPG (UK) = 7.84 L/100 km = 12.8 km/L — a typical modern compact sedan. 15 MPG (pickup truck or old V8) = 15.7 L/100 km. 60+ MPG hybrids = under 4 L/100 km. Everything runs client-side; no values leave your browser.