Fuel cost calculator
Fuel cost = distance ÷ fuel economy × price. Driving 250 miles in a car that does 30 mpg with gas at 3.50 a gallon costs about 29.17.
- Checked on thousands of cases
- Updated November 1, 2026
Trip cost
Fuel used : 8.3 gal
= 1 gal
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How it works
Formula: Cost = distance ÷ mpg × price per gallon
In US units, the fuel used is the distance divided by the fuel economy (miles per gallon). In metric units, it is the distance multiplied by the consumption in liters per 100 km, divided by 100. Multiply the fuel used by the price per gallon or per liter to get the cost. Tick 'Round trip' to double the distance, and enter the number of people to split the cost. Real consumption depends on speed, traffic, load and weather.
Fuel used by distance and fuel economy
| Distance | 20 mpg | 25 mpg | 30 mpg | 35 mpg | 40 mpg |
|---|---|---|---|---|---|
| 10 mi | 0.5 gal | 0.4 gal | 0.3 gal | 0.3 gal | 0.3 gal |
| 50 mi | 2.5 gal | 2 gal | 1.7 gal | 1.4 gal | 1.3 gal |
| 100 mi | 5 gal | 4 gal | 3.3 gal | 2.9 gal | 2.5 gal |
| 200 mi | 10 gal | 8 gal | 6.7 gal | 5.7 gal | 5 gal |
| 300 mi | 15 gal | 12 gal | 10 gal | 8.6 gal | 7.5 gal |
| 500 mi | 25 gal | 20 gal | 16.7 gal | 14.3 gal | 12.5 gal |
| 1,000 mi | 50 gal | 40 gal | 33.3 gal | 28.6 gal | 25 gal |
Frequently asked questions
How do I calculate the fuel cost of a trip?
Divide the distance by your fuel economy to get the gallons used, then multiply by the price per gallon. 300 miles at 25 mpg is 12 gallons; at 3.50 a gallon, that is 42.
How do I calculate it with liters per 100 km?
Multiply the distance by the consumption and divide by 100 to get the liters, then multiply by the price per liter. 400 km at 6 L/100 km is 24 L.
Why is my real cost different?
Fuel economy changes with speed, air conditioning, load, traffic and weather. Highway driving above 70 mph uses noticeably more fuel.