MPG Calculator
Enter the distance you drove and the fuel you used to find your fuel economy. The result is shown in miles per gallon, liters per 100 km and kilometers per liter, whichever units you start with.
Last updated October 23, 2026
Result
30 MPG
| Unit | Value |
|---|---|
| Miles per gallon (MPG) | 30 |
| Liters per 100 km | 7.84 |
| Kilometers per liter | 12.75 |
For the most accurate figure, fill the tank at the same pump before and after the trip.
Show the work
Formula: MPG = miles / gallons
- Entered: 360 miles driven on 12 gallons.
- MPG = 360 miles / 12 gallons = 30.
- L/100 km = 12 gal x 3.785411784 x 100 / (360 mi x 1.609344) = 7.84.
- km per liter = (360 mi x 1.609344) / (12 gal x 3.785411784) = 12.75.
Result: 30 MPG
How MPG is calculated
MPG = miles driven ÷ gallons used
L/100 km = 235.215 ÷ MPG
Miles per gallon is the distance you drove divided by the fuel you used. 360 miles on 12 gallons is 360 ÷ 12 = 30 MPG.
Liters per 100 km and MPG are reciprocals, so 235.215 ÷ MPG gives L/100 km and 235.215 ÷ L/100 km gives MPG (US gallons). Kilometers per liter is 100 ÷ L/100 km. For an accurate figure, fill the tank, reset the trip meter, drive normally, then refill at the same pump and enter the gallons added.
See how we calculate for the formulas, sources and review schedule behind every calculator.
Also useful alongside this calculator: Average Calculator, Mileage Calculator and EV Charging Cost Calculator.
How to use the MPG Calculator
- Choose US or metric units.
- Enter the distance driven and the fuel used.
- Read your MPG, L/100 km and km per liter, then use Copy, Print or Share.
Worked example
You drive 360 miles and refill with 12 gallons. MPG = 360 ÷ 12 = 30, which is 7.84 L/100 km or 12.75 km per liter.
| MPG | L/100 km |
|---|---|
| 20 | 11.76 |
| 25 | 9.41 |
| 30 | 7.84 |
| 35 | 6.72 |
| 40 | 5.88 |
| 50 | 4.70 |
Frequently asked questions
How do I calculate MPG?
Divide the miles you drove by the gallons of fuel you used.
How do I convert MPG to L/100 km?
Divide 235.215 by the MPG. For example, 30 MPG is 235.215 ÷ 30 = 7.84 L/100 km (US gallons).
What is a good MPG?
Many gasoline cars get about 25 to 35 MPG combined; large trucks and SUVs are often lower and hybrids higher.
Is a US gallon the same as a UK gallon?
No. This calculator uses the US gallon (3.785 liters). A UK imperial gallon is about 4.546 liters, so UK MPG figures are higher.
Are my numbers stored or sent anywhere?
No. The calculation runs in your browser and nothing you enter is saved or uploaded.