L/100km · mpg (US) · mpg (UK) · km/L
Free Fuel Economy Converter
Convert fuel economy units instantly — MPG (US/UK), L/100km, km/L, mL/km. Type into any field and all others update. Free, symmetrical, no sign-up.
Why symmetrical conversion?
How This Converter Works
Fuel economy uses inverse units — MPG measures distance per volume (higher = better), while L/100km measures volume per distance (lower = better). Our converter handles both systems including UK and US gallon differences.
Quick reference
Common Conversions
| MPG (US) | L/100km | km/L | Vehicle Type |
|---|---|---|---|
| 15 MPG | 15.68 L/100km | 6.37 km/L | Large truck or SUV |
| 25 MPG | 9.41 L/100km | 10.63 km/L | Average passenger car |
| 35 MPG | 6.72 L/100km | 14.87 km/L | Efficient compact car |
| 45 MPG | 5.23 L/100km | 19.11 km/L | Hybrid vehicle |
| 55 MPG | 4.28 L/100km | 23.38 km/L | High-efficiency hybrid |
FAQ
Frequently Asked Questions
1How do I convert MPG to L/100km?
Divide 235.214 by the MPG value. So 30 MPG = 235.214 ÷ 30 = 7.84 L/100km. Note: this uses the US gallon. For UK MPG, the constant is 282.481.
2Why are US and UK MPG different?
The US gallon (3.785 L) is smaller than the UK imperial gallon (4.546 L). A car with a UK rating of 40 MPG is not as fuel-efficient as it sounds — the US equivalent is about 33.3 MPG.
3What is a good fuel economy in L/100km?
Below 6.0 L/100km is considered efficient for a petrol car. Below 4.5 L/100km is excellent. Diesel cars typically achieve 1–2 L/100km better than petrol equivalents.
4Why does upgrading from 10 to 20 MPG save more fuel than 30 to 40 MPG?
Because MPG is a reciprocal scale. Going from 10 to 20 MPG saves 11.76 L/100km, while going from 30 to 40 MPG only saves 1.96 L/100km — even though both are 10 MPG improvements on paper.
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