MPG to L/100km Converter
| US mpg | L/100km | The car |
|---|---|---|
| 10 | 23.52 | old V8 truck |
| 15 | 15.68 | big SUV in town |
| 20 | 11.76 | aging pickup |
| 25 | 9.41 | US fleet average |
| 30 | 7.84 | compact sedan |
| 35 | 6.72 | thrifty hatchback |
| 40 | 5.88 | hybrid sedan |
| 50 | 4.70 | Prius-class hybrid |
| 60 | 3.92 | plug-in hybrid cruising |
America rates cars in miles per gallon - distance per fuel - while most of the world rates them in liters per 100 kilometers, fuel per distance. The two scales run in opposite directions, so the mental math breaks the moment you cross markets: a 30 mpg American sedan is 7.8 L/100km, and the European buyer's lower-is-better instinct suddenly applies. Type either number and the converter shows both scales, plus km/L and the UK imperial-gallon reading.
The exact bridge is L/100km = 235.215 divided by US mpg, because one gallon is 3.785411784 liters and one hundred kilometers is 62.1371 miles - multiply and simplify and the constant falls out. The table below gives the ladder at whole mpg steps; the EPA's own ratings come from dynamometer test schedules, which is why window-sticker numbers and real tank math can drift apart.
How to use
- Type your US mpg and the L/100km, UK mpg and km/L figures update instantly - or type an L/100km figure to convert back.
- Remember the direction flip: mpg goes up when a car gets thriftier, L/100km goes down. 25 mpg = 9.4, 50 mpg = 4.7.
- Comparing a UK-listed car? Imperial gallons are 4.546 liters, so UK mpg runs about 20 percent higher for the same car - the converter's UK line handles it.
Frequently asked questions
Why is lower L/100km better when higher mpg is better?
Because the axes are inverted: mpg measures how far a gallon takes you (bigger is better), L/100km measures how much fuel a fixed trip consumes (smaller is better). The flip hides a real insight - going from 15 to 20 mpg saves more fuel per mile than going from 40 to 45, which a straight mpg comparison completely misses.
Where does the 235.2 constant come from?
One hundred kilometers is 62.1371 miles and one US gallon is 3.78541 liters, so L/100km = (100 x 3.78541) / (mpg x 1.60934) = 235.215 / mpg. Every chart you see is this one division; the converter keeps the full precision and rounds only the display.
Is UK mpg the same as US mpg?
No - the imperial gallon holds 4.546 liters against the US gallon's 3.785, so a car quoted 40 mpg (UK) is really 33.3 mpg (US) for identical fuel burn. The UK bridge constant is 282.481 instead of 235.215. This is the classic trap in imported car brochures: always check which gallon the number was measured with.
What is a good L/100km figure?
Modern context in metric terms: a thrifty hybrid sits near 4 to 5 L/100km (47 to 59 mpg), a typical compact near 6 to 7 (34 to 40 mpg), and a full-size pickup near 11 to 13 (18 to 21 mpg). City driving costs about 20 to 25 percent against highway figures because acceleration, not cruising, is what burns fuel.
Do EVs use MPGe?
Yes - the EPA's MPGe rates electric cars by how many miles they travel on the energy equal to one gallon of gasoline (33.7 kWh). It preserves comparability on the window sticker, but since EVs charge by the kilowatt-hour and pay per kWh rather than per gallon, the honest running-cost conversion is price per mile, not MPGe alone.