Fuel cost per mile equals fuel money divided by miles driven between comparable fill-ups. If 12.4 US gallons cost $46.38 and the odometer advanced 356 miles, the fuel cost is $0.130 per mile. That unit cost describes the vehicle and driving conditions in that interval; it does not include parking, insurance, depreciation, or a future route.
Worked example with numbers
A driver fills to the first automatic click, records 52,140 miles, then repeats the same routine at 52,496 miles. The second receipt is $46.38 for 12.4 gallons. Divide $46.38 by 356 miles: $0.1303 per mile. For a 180-mile journey, multiplying 180 by $0.1303 gives a fuel-only planning figure of $23.45. The receipt is the observed cost; the journey figure is a projection.
How to make the calculation
Use at least two full, comparable fill-ups. Subtract the starting odometer from the ending odometer, then divide the money on the later receipt by that distance. Record the currency, distance unit, fuel grade, and date. A period that includes towing, winter idling, mountain roads, or mostly motorway driving can be useful, but label it rather than treating it as every-season performance.
Check the units and assumptions
Check the denominator before trusting the result. A 356-mile interval with $46.38 of fuel is $0.130 per mile, not $13.03 per mile and not 13 cents per gallon. If the odometer is in kilometres, calculate cost per kilometre first or convert the distance before presenting a per-mile number. Keep receipts from the same vehicle; mixing two vehicles produces a number with no physical meaning.
Common mistakes
A common mistake is dividing gallons by miles and calling the result cost per mile; that produces gallons per mile. Another is using a single partial refill, where the tank level at either end is unknown. Do not fold a supermarket receipt, a car wash, or a membership fee into the fuel numerator unless the question really is total motoring cost.
When this result does not apply
Fuel cost per mile is retrospective and variable. Fuel prices change, and consumption changes with speed, load, temperature, tyre pressure, traffic, and route. It is suitable for a personal baseline and scenario comparison, not for a tax record, a vehicle warranty claim, or a promise about another driver’s consumption.
Source for the external fact
The U.S. Department of Energy’s Alternative Fuels Data Center explains that a vehicle fuel-cost comparison needs both the energy price and the vehicle’s consumption; the same separation applies to a petrol or diesel record. Its home-charging guidance is a useful parallel example of price multiplied by energy.
Related calculators
Use the fuel-cost calculator for a distance-and-consumption scenario, the MPG calculator to inspect the same fill-ups as efficiency, and the trip-cost splitter when travellers share a route.