This fuel efficiency converter changes distance per volume of fuel between kilometers per liter, miles per US gallon, miles per UK (imperial) gallon and miles per liter. The factors come from exact definitions: 1 mile = 1.609344 km, 1 US gallon = 3.785411784 L and 1 UK gallon = 4.54609 L. So 1 km/L = 2.35215 US mpg = 2.82481 UK mpg.
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How to use the fuel efficiency converter
- Enter the figure, for example 15 km/L from a car brochure.
- Choose its unit and the unit you want, such as km/L to US mpg.
- Read the fuel efficiency converter result: 15 km/L = 35.3 US mpg.
km per liter is common in India, Japan and parts of Latin America. For liters per 100 km, which works in the opposite direction, use the fuel economy converter.
What does distance per unit volume mean?
The fuel efficiency converter handles distance travelled per unit volume of fuel, such as kilometers per liter or miles per US or UK gallon. It complements the fuel consumption converter, which also covers liters per 100 km.
Conversion formula
The fuel efficiency converter stores every unit as a multiple of the base unit, the meter per cubic meter (m/m³). To convert:
value in target unit = value × (factor of source unit ÷ factor of target unit)
where each factor is the size of the unit in meters per cubic meter.
Common distance per unit volume conversions
| From | To | 1 unit equals |
|---|---|---|
| mile per US gallon (mpg US) | kilometer per liter (km/L) | 0.4251437 km/L |
| kilometer per liter (km/L) | mile per US gallon (mpg US) | 2.352146 mpg US |
| mile per Imperial gallon (mpg UK) | mile per US gallon (mpg US) | 0.8326746 mpg US |
| kilometer per liter (km/L) | meter per liter (m/L) | 1,000 m/L |
Fuel efficiency converter worked example
Convert 25 miles per US gallon to kilometers per liter:
- Factor of mpg US = 425,143.71 m/m³
- Factor of km/L = 1,000,000 m/m³
- 25 × 425,143.71 ÷ 1,000,000 = 10.62859 km/L
Distance per unit volume unit reference
| Unit | Symbol | Group | Equals (m/m³) |
|---|---|---|---|
| Meter per Cubic Meter | m/m³ | SI | 1 |
| Kilometer per Liter | km/L | Metric | 1,000,000 |
| Meter per Liter | m/L | Metric | 1,000 |
| Mile per US Gallon | mpg US | US | 425,143.7074 |
| Mile per Imperial Gallon | mpg UK | Imperial | 354,006.1899 |
| Kilometer per US Gallon | km/gal US | US | 264,172.0524 |
| Kilometer per Imperial Gallon | km/gal UK | Imperial | 219,969.2483 |
Reverse factors for each distance per unit volume unit
The reference table gives each unit in meter per cubic meters. To go the other way, divide by that factor; the list below does the division for you.
- Kilometer per Liter (km/L), Metric: 1 km/L = 1,000,000 m/m³, so 1 m/m³ = 1 × 10−6 km/L.
- Meter per Liter (m/L), Metric: 1 m/L = 1,000 m/m³, so 1 m/m³ = 0.001 m/L.
- Mile per US Gallon (mpg US), US: 1 mpg US = 425,143.7 m/m³, so 1 m/m³ = 2.35215 × 10−6 mpg US.
- Mile per Imperial Gallon (mpg UK), Imperial: 1 mpg UK = 354,006.2 m/m³, so 1 m/m³ = 2.82481 × 10−6 mpg UK.
- Kilometer per US Gallon (km/gal US), US: 1 km/gal US = 264,172.1 m/m³, so 1 m/m³ = 3.78541 × 10−6 km/gal US.
- Kilometer per Imperial Gallon (km/gal UK), Imperial: 1 km/gal UK = 219,969.2 m/m³, so 1 m/m³ = 4.54609 × 10−6 km/gal UK.
km/L to mpg chart
Multiply km/L by 2.35215 for US mpg, or by 2.82481 for UK mpg. The last column gives the matching L/100 km:
| km/L | US mpg | UK mpg | L/100 km |
|---|---|---|---|
| 8 | 18.8 | 22.6 | 12.5 |
| 10 | 23.5 | 28.2 | 10 |
| 12 | 28.2 | 33.9 | 8.33 |
| 15 | 35.3 | 42.4 | 6.67 |
| 18 | 42.3 | 50.8 | 5.56 |
| 20 | 47 | 56.5 | 5 |
| 25 | 58.8 | 70.6 | 4 |
| 30 | 70.6 | 84.7 | 3.33 |
For mpg to km/L, divide US mpg by 2.35215: 40 US mpg = 17.0 km/L.
US and UK gallons
The imperial gallon is about 20 % larger than the US gallon, so the same car shows a higher number in UK mpg. For km/L to mpg UK, multiply by 2.82481; to switch UK mpg to US mpg, divide by 1.20095. Check which gallon a figure uses before comparing.
Planning a trip with mixed units
Suppose you are driving 500 km in a rented car rated at 35 mpg (US). The fuel efficiency converter turns 35 mpg into about 14.9 km/L, so the trip needs roughly 33.6 litres. If your own car manages 15 km/L, it would use about 33.3 litres, which is almost the same. Use the converted figure for budgeting and add a margin for hills and air conditioning.
Related converters and calculators
Related fuel tools:
- Fuel economy converter: L/100 km and mpg
- km per kg converter: CNG and hydrogen
- Gas mileage calculator: mpg from a fill-up
- Fuel cost calculator: trip cost
- Volume converter: liters and gallons
Sources
NIST Special Publication 811, Appendix B; US DOE/EPA: fueleconomy.gov.
Questions about this calculator
How do I convert km/L to mpg?
Multiply by 2.35215 for US mpg. For example, 12 km/L = 28.2 US mpg.
How do I convert mpg to km/L?
Divide US mpg by 2.35215, or multiply by 0.425144. For example, 30 US mpg = 12.75 km/L.
How do I convert km/L to UK mpg?
Multiply by 2.82481. For example, 20 km/L = 56.5 UK mpg.
How do I convert km/L to L/100 km?
Divide 100 by the km/L value. For example, 16 km/L = 6.25 L/100 km.
Why do UK and US mpg differ?
A UK (imperial) gallon is 4.54609 L and a US gallon is 3.785411784 L, so UK mpg figures are about 20 % higher for the same car.
Check the assumptions and units before relying on a result. Financial, tax and health estimates do not replace advice for your individual circumstances.
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