Fuel Efficiency Converter
Convert between MPG (US), MPG (Imperial UK), km/L, and L/100km — the four most common fuel-economy units worldwide.
Inputs
Primary metric (L/100km)
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US MPG
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UK MPG
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km / L
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Efficiency rating
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About Fuel Efficiency Converter
Why US and UK MPG differ
A US gallon is 3.785 L; an Imperial gallon is 4.546 L (~20% larger). So a UK car rated 40 MPG is the same efficiency as a US car rated 33 MPG.
L/100km vs MPG philosophy
MPG is "distance per fuel" — bigger is better. L/100km is "fuel per distance" — smaller is better. L/100km scales linearly, making 30 vs 40 MPG less misleading than it looks.
EV equivalents
EPA uses MPGe: 33.7 kWh = 1 gallon. A 100 MPGe car uses 33.7 kWh per 100 miles. Most current EVs achieve 100-130 MPGe city, 90-115 highway.