12+ conversions · 4 units
Convert fuel economy units instantly with ConvertNow. 12+ free conversions, verified formulas, and reference tables. No signup required.
Welcome to the ConvertNow fuel economy converter hub. Whether you are a student solving homework, a professional completing a project, or a traveller navigating unfamiliar units, our free fuel economy conversion tools give you instant, accurate results backed by internationally verified constants.
Fuel economy measurement reflects regional habits. Miles per gallon (mpg) dominates the US and UK, but the two countries use different gallon sizes (US = 3.785 L; imperial = 4.546 L). Most of the world uses litres per 100 kilometres (L/100 km), which inverts the ratio so lower is better — the opposite of mpg.
Fuel economy conversion affects vehicle purchase decisions and carbon footprint calculations. A car rated at 25 US mpg equates to 9.4 L/100 km — a figure Europeans instantly understand as efficient or not. Fleet managers compare across regions using consistent units.
Fleet managers, car buyers, logistics coordinators, and environmentally conscious drivers comparing efficiency.
US mpg vs UK mpg (different gallon sizes). A 25 US mpg car gets ~30 UK mpg. Also, mpg and L/100 km are inverse — higher mpg means lower L/100 km.
| Unit | Symbol | Base Equivalent | Common Use |
|---|---|---|---|
| Miles per gallon (US) | mpg | 235.2 / L/100km | US vehicles |
| Miles per gallon (UK) | mpg | 282.5 / L/100km | UK vehicles |
| Litres per 100 km | L/100km | Base metric | EU, AU, CA |
| Kilometres per litre | km/L | 100 / L/100km | Japan, India |
| Common Value | Equals |
|---|---|
| 25 US mpg | 9.4 L/100km |
| 7 L/100km | 33.6 mpg |
| 50 UK mpg | 5.6 L/100km |
| 10 km/L | 10 L/100km |
Higher mpg means better efficiency. Lower L/100 km means better efficiency. They are inverses. 25 US mpg ≈ 9.4 L/100 km (good). 50 US mpg ≈ 4.7 L/100 km (excellent).
US and UK gallons are different sizes (3.785 L vs 4.546 L). A car gets a higher mpg number in the UK because the gallon is larger, meaning fewer gallons are used per mile.
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