Fuel Economy Converter
Convert mpg (US & UK), km/L and L/100km.
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Kilometer / Liter (km/L)
Mile / US Gallon (mpg (US))
| Unit | 1 km/L equals |
|---|---|
| Kilometer / Liter (km/L) | 1 |
| Mile / US Gallon (mpg (US)) | 2.35214 |
| Mile / Imp Gallon (mpg (UK)) | 2.82481 |
| Liter / 100km (L/100km) | 100 |
How it works
- 25 mpg (US) ≈ 9.4 L/100km
- 10 km/L ≈ 23.5 mpg
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Frequently asked
Why is mpg vs L/100km not linear?
They are reciprocal measures, so the conversion is value-dependent.
Where you'll actually use this
Fuel economy compares how far a vehicle travels per unit of fuel — or, inversely, how much fuel it uses per unit of distance.
- Buying a car
US listings show MPG (higher is better). Most of the rest of the world shows L/100 km (lower is better).
- Road trips
Estimate fuel cost: distance ÷ economy × price per gallon (or liter).
- Fleet management
Standardize across regions by converting all vehicles to the same metric.
Common mistakes to avoid
- MPG isn't linear
Going from 10 → 20 MPG saves much more fuel than 40 → 50 MPG, even though both jumps are '+10 MPG'.
- US MPG ≠ UK MPG
A UK (imperial) gallon is 20% larger than a US gallon, so UK MPG values are higher for the same vehicle.
Did you know?
L/100 km is directly proportional to fuel cost — twice the number means twice the bill. MPG isn't.
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Accuracy & sources
How this tool is built and verified.
- Source
- Standards-aligned factors
- Last reviewed
- Q2 2026
- Status
- Verified
- International System of Units (SI)BIPM — Bureau International des Poids et Mesures · The International System of Units (SI Brochure), 9th edition
- ISO 80000 — Quantities and UnitsISO / IEC · ISO 80000-1:2022
- Standards aligned
- Formula verified
- Editor reviewed
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