Fuel Efficiency Calculator
Calculate your vehicle fuel efficiency in MPG or km/L.
Enter distance driven and fuel used to find out how efficient your car really is.
Fuel efficiency measures how far a vehicle travels per unit of fuel — expressed as miles per gallon (MPG) in the US and UK, or liters per 100 km (L/100km) in most of the rest of the world.
The core formulas:
MPG = Miles Driven / Gallons Used
L/100km = (Liters Used / Kilometers Driven) × 100
Converting between the two:
L/100km = 235.21 / MPG (US gallons)
MPG = 235.21 / L/100km
Monthly fuel cost:
Monthly Cost = (Monthly Miles / MPG) × Price per Gallon
What each variable means:
- Miles/km Driven — measure from your odometer at fill-up: end reading minus start reading
- Gallons/Liters Used — exactly what it took to fill the tank back to full each time
- Price per Gallon — current pump price in your area
Worked example: You fill up when the odometer reads 24,850 miles. You drove since the last fill-up (at 24,210 miles) and used 11.4 gallons.
Miles driven = 24,850 − 24,210 = 640 miles MPG = 640 / 11.4 = 56.1 MPG
At $3.60/gallon driving 1,200 miles/month: Monthly cost = (1,200 / 56.1) × $3.60 = 21.39 × $3.60 = $77/month
EPA fuel economy ratings (2024 US averages):
- Compact car: 28–36 MPG combined
- SUV/crossover: 22–30 MPG combined
- Full-size pickup: 16–22 MPG combined
- Hybrid sedan: 45–55 MPG combined
- Plug-in hybrid: 40–60 MPG (gas mode)
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
SuperGlobalCalculator is independently built and maintained. See how we build and verify our calculators.