Fuel Efficiency Converter — MPG to L/100km & Km/L

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How to use Fuel Efficiency Converter

Enter the fuel economy figure in the “From” field — for example 35 for 35 MPG.
Select its system in the first dropdown: MPG (US), MPG (UK), L/100km or Km/Liter.
Select the system you want in the second dropdown — the converted figure appears instantly.
Tap the swap button to reverse direction, e.g. L/100km → MPG becomes MPG → L/100km.

What is Fuel Efficiency Converter?

A fuel efficiency converter translates fuel economy figures between the systems used around the world: miles per gallon (US), miles per gallon (UK), liters per 100 kilometers, and kilometers per liter. These are not simple multiples — MPG and km/L measure distance per fuel while L/100km measures fuel per distance, so converting requires inverting: L/100km = 235.215 ÷ MPG(US).

The two MPGs are a trap: the UK (imperial) gallon is 4.546 L versus the US 3.785 L, so a British 50 MPG equals only 41.6 US MPG for identical consumption. This tool keeps all four systems straight, including that inversion.

About the Fuel Efficiency Converter

This converter handles US MPG, UK MPG, L/100km and km/L — converting between any pair instantly, doing the reciprocal math internally.

Use it to compare cars across markets: a US car rated 35 MPG uses 6.72 L/100km; a European spec of 5.0 L/100km equals 47 US MPG or 56.5 UK MPG; a Japanese figure of 20 km/L is 5.0 L/100km. Note that lower is better in L/100km while higher is better in MPG and km/L — a frequent source of confusion this tool removes.

Anchors: 235.215 ÷ US MPG = L/100km, 282.481 ÷ UK MPG = L/100km, and km/L × 2.352 = US MPG. Everything is computed exactly in your browser.

Frequently Asked Questions

Divide 235.215 by the MPG figure: 30 MPG → 7.84 L/100km; 50 MPG → 4.70 L/100km. The same formula works in reverse because the relationship is reciprocal.

The gallons differ: imperial = 4.546 L, US = 3.785 L. The same car scores about 20% higher in UK MPG — 40 US MPG is 48 UK MPG with identical fuel use.

Higher is better for MPG and km/L (more distance per fuel); lower is better for L/100km (less fuel per distance). 5 L/100km is excellent; 15 L/100km is thirsty.

Roughly: small hybrids reach 4–5 L/100km (47–59 US MPG), average modern cars 6–8 L/100km (29–39 MPG), SUVs and trucks 10–15 L/100km (16–24 MPG).

Cost per 100 km = L/100km × price per liter. A 7 L/100km car at $1.50/L costs $10.50 per 100 km, or about $0.105 per km — handy for trip budgeting.