Fuel Consumption Calculator
Driving 650 km on 45 liters of fuel works out to 6.92 L/100 km, which is about 34 US MPG. This fuel consumption calculator turns a real trip, the distance driven and the fuel it took, into all four common economy measures at once: liters per 100 km, kilometers per liter, US MPG, and UK MPG. Fill the tank, drive, refill, and enter what the pump says.
Quick answer
Fuel consumption is fuel used divided by distance covered. The full-tank-to-full-tank method gives the most honest number.
Fuel consumption
6.92 L/100 km
km per liter
14.44
US MPG
33.98
UK MPG
40.8
What this tells you
- •Fuel consumption is fuel used divided by distance covered. The full-tank-to-full-tank method gives the most honest number.
- •L/100 km is the metric standard, and lower is better. MPG flips the ratio, so higher is better.
- •US and UK MPG differ because the UK gallon is 20 percent bigger.
- •Real-world consumption usually runs 10 to 20 percent above the manufacturer's laboratory figure.
How to Use
- 1Fill your tank completely and note the odometer or reset the trip meter.
- 2Drive normally, then fill up again. The pump shows exactly how much fuel you used.
- 3Enter the distance driven and the fuel from that second fill.
- 4Read your consumption in all four measures.
How It Works
Formula
L/100 km = (liters used / km driven) x 100Divide fuel by distance and scale to 100 km. For 45 liters over 650 km, that is 45 / 650 x 100 = 6.92 L/100 km. Kilometers per liter is the straight division the other way, 650 / 45 = 14.4 km/L. MPG converts both units, miles for distance and gallons for fuel, using 1.609 km per mile and 3.785 liters per US gallon.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
Mid-size car on a mixed route
45 liters across 650 km is a typical mixed city-highway result for a mid-size car.
US road trip in miles and gallons
400 miles on 12 US gallons converts to about 7.1 liters per 100 km.
Efficient hybrid in the city
Hybrids shine in stop-and-go driving where regenerative braking recovers energy.
L/100 km to MPG Conversion
How the metric and US measures line up.
| L/100 km | km/L | US MPG |
|---|---|---|
| 4.0 | 25.0 | 58.8 |
| 5.0 | 20.0 | 47.0 |
| 6.0 | 16.7 | 39.2 |
| 7.0 | 14.3 | 33.6 |
| 8.0 | 12.5 | 29.4 |
| 10.0 | 10.0 | 23.5 |
| 12.0 | 8.3 | 19.6 |
Common mistakes
- Trusting the dashboard readout alone. Onboard computers often flatter by 5 to 10 percent. The pump-to-pump method is the ground truth.
- Mixing gallon standards. 40 MPG on UK gallons is only 33 MPG on US gallons, the same car and the same fuel.
- Measuring a single short trip. Cold starts burn extra fuel, so measure across at least a few hundred kilometers for a stable figure.