What Is a Fuel Consumption Unit Calculator?
Fuel economy is expressed differently around the world — most of Europe and much of the rest of the world uses liters per 100 kilometers (L/100km), while the US uses miles per gallon (MPG), and the UK and some Commonwealth countries use MPG based on the larger Imperial gallon. This calculator converts between all three using the standard published conversion constants.
Whether you're comparing a car's spec sheet from a different country, reading an import vehicle's window sticker, or just trying to understand a European road-trip fuel budget in familiar terms, this tool handles the conversion instantly.
How to Read Your Results
Liters per 100km (L/100km)
This is a consumption figure — how much fuel is used to travel a fixed distance. Lower numbers mean better fuel economy.
US MPG
Miles per US gallon (3.785 liters) — an efficiency figure where higher numbers mean better fuel economy.
Imperial MPG
Miles per Imperial gallon (4.546 liters), used in the UK and some Commonwealth countries. Because the Imperial gallon is larger, Imperial MPG numbers are always higher than US MPG for the same car.
Kilometers per Liter
A straightforward efficiency figure — how far the vehicle travels on one liter of fuel — useful for quick mental comparisons.
Real-World Example
A European car's spec sheet lists combined fuel consumption of 6.5 L/100km. What does that mean in MPG?
| Unit | Value |
|---|---|
| Liters per 100km | 6.5 L/100km |
| US MPG | ≈36.2 MPG |
| Imperial MPG | ≈43.5 MPG |
Dividing 235.215 by 6.5 gives about 36.2 US MPG, and dividing 282.481 by 6.5 gives about 43.5 Imperial MPG — the same car, three different-looking numbers depending on which country's units you use.
Tips for Working With Fuel Economy Units
- Never assume US MPG and Imperial MPG are interchangeable — they differ by about 20% for the identical fuel consumption.
- L/100km is linear with fuel cost: a car using 4 L/100km burns exactly half the fuel of one using 8 L/100km over the same distance.
- MPG is not linear — equal MPG gains at low MPG values save far more fuel than the same gains at high MPG values.
- Real-world fuel economy typically differs from window-sticker or spec-sheet ratings depending on driving style, terrain, and load.
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Last updated: August 2026 · Reviewed by: Simple Calculator Tools Editorial Team