Fuel Economy Converter
Convert between US MPG, UK imperial MPG, liters per 100 kilometers, and kilometers per liter as you type.
Fuel Economy Converter converts in your browser.
Compare fuel economy across countries
A car rated in miles per gallon in the US, the same model listed in liters per 100 kilometers in Europe, and a UK review quoting imperial MPG: the numbers can’t be compared until they share a unit. Type a figure, choose the units, and the converter shows the equivalent in every other measure. MPG and km/L count distance per fuel, where higher is better; L/100 km counts fuel per distance, where lower is better.
How to use the Fuel Economy Converter
- Type the fuel economy figure. It must be greater than 0 — decimals such as 7.8 are fine.
- Choose the unit it is in and the unit you want. US and UK imperial MPG are listed separately; Swap units flips them.
- Read the result, the formula used, and the same figure in the other units. Copy Result copies the main conversion; Reset returns to 30 MPG (US) in L/100 km.
The method
L/100 km = 235.2145833 ÷ MPG (US)
L/100 km = 282.4809363 ÷ MPG (Imperial/UK)
L/100 km = 100 ÷ km/L
1 MPG (US) = 1.200949926 MPG (Imperial/UK)
The constants come from exact definitions: a mile is 1.609344 km, a US gallon is 3.785411784 L, and a UK imperial gallon is 4.54609 L. Converting between two distance-per-fuel units (MPG and km/L) is a plain multiplication. Converting between MPG or km/L and L/100 km flips the measurement upside down, so the result is a constant divided by your value — doubling MPG halves L/100 km.
| From | To |
|---|---|
| 30 MPG (US) | 7.840486111 L/100 km |
| 40 MPG (US) | 5.880364583 L/100 km |
| 50 MPG (Imperial/UK) | 5.649618727 L/100 km |
| 6 L/100 km | 39.20243056 MPG (US) |
| 6 L/100 km | 47.08015606 MPG (Imperial/UK) |
| 15 km/L | 6.666666667 L/100 km |
| 30 MPG (US) | 36.02849777 MPG (Imperial/UK) |
Converted on your device
- The conversion runs in your browser as you type; nothing is sent to a server.
- The values you enter and the results are not sent to Looty Tools or stored.
- The converter area is masked from session-recording analytics, so what you enter isn’t captured in recordings.
Limitations
- Values must be greater than 0. A fuel economy of 0 has no finite equivalent in the other units, so it is rejected rather than shown as infinity.
- It converts units only. It doesn’t estimate trip fuel, cost, or emissions, and official ratings from different test cycles (such as EPA and WLTP) can differ even after conversion.
- MPG labeled without a country could be either US or imperial — check the source before converting.
- Results are shown to up to 10 significant digits; very large or very small results switch to scientific notation.
Related converters
- Length ConverterConvert inches, feet, meters, and other lengths.
- Volume ConverterConvert liters, US and UK gallons, cups, and other volumes.
- Speed ConverterConvert miles per hour, kilometers per hour, and other speeds.
Guides
- MPG vs. L/100 kmHow miles per gallon and liters per 100 km measure fuel economy in opposite ways, the reciprocal formula, and conversion tables both ways.
- US vs. UK MPGWhy the same car gets about 20% more miles per imperial gallon than per US gallon, how to convert between them, and how to tell which one you have.
- Why Lower L/100 km Is BetterFuel per distance versus distance per fuel, the MPG illusion, and why liters per 100 km makes fuel savings easier to compare.
Fuel Economy Converter FAQ
- What is 30 MPG in liters per 100 km?
- 30 US miles per gallon is about 7.84 L/100 km (7.840486111). In UK imperial MPG, 30 MPG is about 9.42 L/100 km.
- Why isn’t MPG to L/100 km a simple multiplication?
- The two measure opposite things. MPG is distance per fuel; L/100 km is fuel per distance. Converting one to the other means taking a reciprocal: L/100 km = 235.2145833 ÷ MPG (US), or 282.4809363 ÷ MPG (Imperial/UK).
- What is the difference between US and UK MPG?
- The gallon. A US gallon is 3.785411784 liters and a UK imperial gallon is 4.54609 liters, so the same car gets more miles per imperial gallon: 30 MPG (US) is about 36.03 MPG (Imperial/UK).
- Is a lower L/100 km better?
- Yes. L/100 km is how much fuel it takes to cover 100 kilometers, so a lower number means less fuel used. With MPG and km/L it is the other way round — higher is better.
- Why can’t I enter 0?
- Because 0 has no finite equivalent. 0 MPG would mean covering no distance at all, and 0 L/100 km would mean using no fuel — infinite fuel economy. The converter asks for a value greater than 0 instead of showing “Infinity”.
- How do I convert km/L to L/100 km?
- Divide 100 by the km/L figure. For example, 12.5 km/L is 100 ÷ 12.5 = 8 L/100 km.
- Are the values I convert sent anywhere?
- No. The conversion runs in your browser as you type. The values you enter and the results are not sent to Looty Tools or stored, and the converter area is masked from session-recording analytics. Refreshing the page resets it.
