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)