Global Fuel CalculatorHow much does gas cost per mile?
Cost per mile is the most useful number in motoring: it turns a fuel price and a fuel economy figure into what each mile actually costs you. The maths is one division, and you can do it in your head once you have seen it worked through.
The formula
Cost per mile = price per gallon ÷ MPG. At $3.50 a gallon and 30 MPG that is 3.50 ÷ 30 = $0.117, or about 11.7 cents per mile. In metric, cost per kilometre = price per litre × L/100km ÷ 100, so 1.50 per litre at 8 L/100km is 0.12 per kilometre.
Cost per mile at different MPG
These examples assume a price of $3.50 per gallon. Swap in your own price and the pattern holds.
| MPG | Gallons per mile | Cost per mile | Cost for 100 miles |
|---|---|---|---|
| 20 | 0.0500 | $0.175 | $17.50 |
| 25 | 0.0400 | $0.140 | $14.00 |
| 30 | 0.0333 | $0.117 | $11.67 |
| 35 | 0.0286 | $0.100 | $10.00 |
| 40 | 0.0250 | $0.088 | $8.75 |
How much will gas cost for my trip?
Divide the distance by your MPG to get the gallons you will need, then multiply by the price. 300 miles at 30 MPG needs 10 gallons, and at $3.50 that is $35. For a round trip, double the distance. In litres, distance × L/100km ÷ 100 gives the fuel needed, and multiplying by the price per litre gives the cost.
Turning it into a monthly fuel budget
Multiply cost per mile by the miles you expect to drive. 1,000 miles at 11.7 cents a mile is about $117. That covers fuel only: parking, tolls, servicing and depreciation come on top.
Common questions
How much does it cost in gas to drive 100 miles?
At 30 MPG and $3.50 a gallon, 100 miles uses 3.33 gallons and costs about $11.67. At 20 MPG the same distance costs $17.50, which shows how much MPG matters.
How much gas would it cost to drive 500 miles?
At 30 MPG you need 16.7 gallons, which at $3.50 a gallon comes to about $58.33. Use the road trip fuel calculator to try your own figures.
Is cost per mile the same as fuel economy?
No. Fuel economy tells you how far a unit of fuel takes you. Cost per mile also folds in the price you paid, so it moves when prices change even if the car does not.
Does cost per mile include servicing and tyres?
No, this is fuel only. Servicing, tyres, insurance and depreciation are extra, and on a newer car they can add up to more than the fuel.