Litres per 100 kilometres — L/100 km — is how fuel consumption is quoted across Europe, Canada, Australia and much of the world. It tells you how much fuel a car needs to cover 100 km, so lower numbers are better. Unlike miles per gallon, it is proportional to the fuel you burn, which makes it a good scale for estimating yearly fuel cost and emissions. This calculator turns a fill-up (or a figure from the brochure) into L/100 km, converts it to km/L and mpg, and then shows what that consumption means over a year.
How to use the liters per 100 km calculator
- Choose what you know: the distance driven and the fuel used, or a L/100 km figure.
- Enter the numbers. Distance can be in km or miles, fuel in litres or gallons.
- Enter your yearly distance and the fuel price per litre.
- Read the consumption in L/100 km, km/L and mpg, plus the fuel, cost and CO2 per year.
The inverse measure has its own page, the kilometers per liter calculator. For all the unit conversions see the fuel economy converter, and for trip budgets the fuel cost calculator.
Liters per 100 km formula
US mpg = 235.215 ÷ (L/100 km)
km/L = 100 ÷ (L/100 km)
Fuel per year = L/100 km × yearly km ÷ 100
CO2 per year = litres × 2.348 kg (gasoline)
- 235.215 = 100 × 3.785411784 L per gallon ÷ 1.609344 km per mile
- 2.348 kg per litre — about 8,887 g of CO2 per US gallon of gasoline (US EPA)
Worked example: 40 litres for 500 km
- Consumption: 40 ÷ 500 × 100 = 8.0 L/100 km.
- Equivalents: 12.5 km/L and 29.4 US mpg.
- Fuel over 15,000 km: 8 × 150 = 1,200 L.
- At $1.50 per litre: $1,800 a year.
- CO2: 1,200 × 2.348 = 2,817 kg a year.
Consumption, mpg and yearly fuel
Each row is calculated with the formulas above, assuming 15,000 km a year and gasoline.
| Consumption | km/L | US mpg | Fuel over 15,000 km | CO2 over 15,000 km (gasoline) |
|---|---|---|---|---|
| 4 L/100 km | 25.0 km/L | 58.8 mpg (US) | 600 L | 1,409 kg |
| 5 L/100 km | 20.0 km/L | 47.0 mpg (US) | 750 L | 1,761 kg |
| 6 L/100 km | 16.7 km/L | 39.2 mpg (US) | 900 L | 2,113 kg |
| 7 L/100 km | 14.3 km/L | 33.6 mpg (US) | 1,050 L | 2,465 kg |
| 8 L/100 km | 12.5 km/L | 29.4 mpg (US) | 1,200 L | 2,817 kg |
| 10 L/100 km | 10.0 km/L | 23.5 mpg (US) | 1,500 L | 3,522 kg |
| 12 L/100 km | 8.3 km/L | 19.6 mpg (US) | 1,800 L | 4,226 kg |
| 15 L/100 km | 6.7 km/L | 15.7 mpg (US) | 2,250 L | 5,283 kg |
Why L/100 km is the better scale for savings
Because L/100 km counts fuel per distance, a change in the number always means the same saving: cutting 1 L/100 km saves 150 litres a year at 15,000 km, whether you go from 10 to 9 or from 6 to 5. Miles per gallon does not work that way. Going from 10 to 20 mpg saves 5 gallons per 100 miles, but going from 30 to 40 mpg saves only 0.83 gallons. That is why swapping a very thirsty vehicle for a moderate one saves more than adding a few mpg to an already efficient car.
Real-world consumption depends on speed, temperature, load and driving style, and varies by several litres per 100 km between city and highway use. A fill-up calculation over a few tanks gives the best estimate for your own car; a single tank can be misleading if the pump clicks off early. Use the figure in the fuel cost calculator to budget a trip or in the gas mileage calculator to track results.
The CO2 figure applies to gasoline, which releases about 2.35 kg of CO2 per litre when burned. Diesel releases more per litre, and electric vehicles produce no tailpipe CO2, although the electricity may be generated with emissions. Treat the figure as a tailpipe estimate rather than a full life-cycle number.
Sources
Unit definitions: 1 US gallon = 3.785411784 litres and 1 mile = 1.609344 km (exact; NIST). The CO2 factor of 8,887 grams per gallon of gasoline comes from the US Environmental Protection Agency's greenhouse-gas equivalencies methodology. Table values were computed from the formulas shown.
Frequently asked questions
How do I calculate L/100 km?
Divide the litres used by the distance in kilometres and multiply by 100. If you used 40 litres to drive 500 km, 40 ÷ 500 × 100 = 8 L/100 km.
How do I convert L/100 km to mpg?
US mpg = 235.215 ÷ (L/100 km). So 8 L/100 km is 29.4 mpg, and 10 L/100 km is 23.5 mpg. For UK mpg use 282.481 ÷ (L/100 km).
Is a lower L/100 km better?
Yes. It is a consumption measure: fewer litres for the same distance. That is the opposite of mpg and km/L, where higher is better.
How is CO2 calculated?
Burning a US gallon of gasoline produces about 8,887 g of CO2 according to the US EPA, which is about 2.348 kg per litre. The result multiplies your yearly fuel by that factor; diesel produces more per litre and electric driving is different.
Why does consumption scale make savings easier to see?
Fuel use is directly proportional to L/100 km, so going from 10 to 8 L/100 km saves the same fuel as going from 8 to 6. With mpg the gains look uneven: 20 to 25 mpg saves less than 12 to 15 mpg of improvement suggests.