Fuel Cost Calculator · Practical guide
Gas Cost per Mile Calculator
Your fuel cost per mile is simply the price per gallon divided by your MPG — see the rate for your car below.
At a glance
The Short Answer
Gas cost per mile is price per gallon ÷ MPG. At $3.50 per gallon, a car getting 25 MPG burns $0.14 of fuel per mile — 14 cents. The calculator above reports cost per mile (and per kilometer) automatically for any trip you enter.
Interactive tool
Fuel Cost Calculator
Enter your own values, then compare the result with the examples below.
Fuel Cost Results
Cost per Mile by Vehicle Efficiency
Assuming gas at $3.50 per gallon:
| Vehicle MPG | Gas Cost per Mile | Cost per 100 Miles |
|---|---|---|
| 15 MPG | $0.233 | $23.33 |
| 20 MPG | $0.175 | $17.50 |
| 25 MPG | $0.140 | $14.00 |
| 30 MPG | $0.117 | $11.67 |
| 35 MPG | $0.100 | $10.00 |
| 40 MPG | $0.088 | $8.75 |
| 50 MPG | $0.070 | $7.00 |
How Gas Prices Move the Number
The per-mile cost scales directly with the pump price. That same 25 MPG car costs $0.12 per mile at $3.00 per gallon and $0.16 per mile at $4.00. Every 50-cent jump in gas prices adds 2 cents per mile at 25 MPG — about $20 extra per 1,000 miles.
Fuel Is Only Part of Driving Cost
Fourteen cents a mile covers gasoline only. The IRS mileage rate (which also accounts for wear, depreciation, insurance, and maintenance) is several times higher — a reminder that fuel is the most visible but not the largest cost of driving. Still, for trip budgeting and commute comparisons, fuel cost per mile is the number that changes day to day.
Comparing Two Vehicles
Per-mile cost makes comparisons easy. Switching from a 20 MPG SUV ($0.175/mile) to a 35 MPG sedan ($0.100/mile) saves $0.075 per mile — $75 every 1,000 miles at $3.50 gas.
Frequently Asked Questions
How do I find my actual MPG?
Fill your tank, reset the trip odometer, drive normally, then divide the miles driven by the gallons needed to refill. Do it over a few tanks for a reliable average.
Does cost per mile include idling?
Not directly — the formula assumes you are moving. Idling burns roughly a quarter to half a gallon per hour, so heavy stop-and-go traffic pushes your real per-mile cost up.
How does cost per mile work in metric units?
Switch the calculator to L/100km mode. It then reports cost per kilometer, and the same logic applies: price per liter times liters used per kilometer.
Is gas cost per mile the same as the IRS mileage rate?
No. The IRS rate covers the full cost of operating a vehicle — fuel, depreciation, insurance, and repairs — and is much higher than fuel cost alone.