MPG calculator
A gas mileage and fuel calculator: enter the miles since your last fill-up and the gallons to refill to get your real MPG and cost per mile.
28.1 MPG
About average for a US car
- Distance
- 320 mi
- L/100 km
- 8.4
- km/L
- 11.9
- Cost per mile
- $0.114
How to measure your MPG
- Fill the tank until the pump clicks off, and reset the trip meter (or note the odometer).
- Drive normally until you need gas again.
- Fill up the same way and note the gallons on the pump and the miles on the trip meter.
- Enter both. For a better average, repeat over two or three tanks.
MPG to L/100 km conversion
| MPG (US) | L/100 km | km/L |
|---|---|---|
| 15 | 15.7 | 6.4 |
| 20 | 11.8 | 8.5 |
| 25 | 9.4 | 10.6 |
| 30 | 7.8 | 12.8 |
| 40 | 5.9 | 17.0 |
| 50 | 4.7 | 21.3 |
Why your MPG drops
- Winter: cold engines, winter fuel blends and heaters cut economy by 10–20%.
- Short trips: the engine never warms up fully.
- Tires: low pressure or bigger, heavier tires. Check a size change with the tire size calculator.
- Speed and load: highway speeds over 65 mph, towing and roof racks.
Planning a drive? Turn your MPG into a trip cost with the gas calculator.
Questions
How do I calculate my gas mileage?
Fill the tank and reset the trip meter. Next time you fill up, divide the miles driven by the gallons it took to refill. 320 miles on 11.4 gallons is 28.1 MPG.
Is my car's MPG display accurate?
Often not exactly: dashboard displays commonly read 1–3 MPG optimistic. Measuring from fill-ups over a few tanks gives your true figure.
How do I convert MPG to L/100 km?
Divide 235.2 by the MPG. 30 MPG is 7.8 L/100 km; 20 MPG is 11.8 L/100 km. The calculator shows both, plus km per liter.
What is good gas mileage?
For US vehicles, around 30 MPG or more is good for a car, 25+ for a crossover, and 20+ for a full-size pickup. Hybrids often reach 45–55 MPG.
