Conversion method
US and imperial gallons have different volumes. US mpg uses 3.785411784 L per gallon; imperial mpg uses 4.54609 L. L/100 km measures consumption, so lower is better, while higher mpg means greater distance per fuel. Inputs must be positive.
L/100 km = ((235.2145833333333 ÷ x)) ÷ 1
10 mpg = 23.521458 L/100 km.
| mpg | L/100 km |
|---|---|
| 1 | 235.214583 |
| 5 | 47.042917 |
| 10 | 23.521458 |
| 25 | 9.408583 |
| 50 | 4.704292 |
| 100 | 2.352146 |
Unit definitions and sources
Distance per fuel and fuel per distance are reciprocal. US and Imperial gallons differ. Enter a positive value.
| Unit and system | Use | Definition | Relationship |
|---|---|---|---|
| Liters per 100 km (L/100 km); metric | Common units | Liters per 100 km measures fuel economy. l100km = (value in L/100 km) × 1. Common use: Vehicle fuel consumption. | Exact definition; numerical display may be rounded |
| Miles per gallon (US) (mpg); us | Common units | Miles per gallon (US) measures fuel economy. l100km = 235.2145833333333 ÷ value in mpg. Common use: Vehicle fuel consumption. | Exact definition; numerical display may be rounded |
| Miles per gallon (imperial) (mpg (imp)); imperial | Common units | Miles per gallon (imperial) measures fuel economy. l100km = 282.48093633182214 ÷ value in mpg (imp). Common use: Vehicle fuel consumption. | Exact definition; numerical display may be rounded |
| Kilometers per liter (km/L); metric | Common units | Kilometers per liter measures fuel economy. l100km = 100 ÷ value in km/L. Common use: Vehicle fuel consumption. | Exact definition; numerical display may be rounded |
Sources: BIPM: International System of Units; NIST: SP 811 Appendix B.8: conversion factors
Precision of fuel economy conversions
All 4 fuel economy units convert through Liters per 100 km (L/100 km). 4 have an exact defined relationship to the base unit and 0 are conventional or measured values. Results and the tables on this page come from the same engine, so a table value can be checked against the converter directly.
Standard display shows up to six decimal places, switching to scientific notation for very large or small values. Calculation uses JavaScript binary floating point independently of display rounding, so extra digits are not a claim about measurement accuracy. Each unit lists its own source; a citation records where the definition comes from, not an independent review. See Conversion methodology for the review and correction process.