Fuel Cost Per Mile Calculator

What cost per mile means

Cost per mile is the price of driving one mile, and the fuel part of it is one division: the price of a gallon divided by the miles your car gets on that gallon.

cost per mile = price per gallon ÷ MPG

At $3.50 a gallon and 30 MPG, that is 3.50 ÷ 30 = $0.1167, or 11.7 cents per mile. Flip it around and you get gallons per mile: 1 ÷ 30 = 0.0333 gallons per mile, so a 100-mile trip burns 3.33 gallons and costs 3.33 × $3.50 = $11.67.

The number is useful because it makes cars comparable at a glance. A 20 MPG truck at the same $3.50 costs 17.5 cents per mile, half a gallon of gas for every 10 miles, while a 50 MPG hybrid costs just 7.0 cents. Over 12,000 miles a year that gap is $1,260: the truck spends $2,100 on fuel, the hybrid $840. The calculator above runs this for whatever price and MPG you enter, and the official fuel-economy figures for every model are published at fueleconomy.gov, run by the EPA and the Department of Energy.

Worked example: $3.50 gas in a 30 MPG car

Put the default numbers through the calculator step by step.

• Cost per mile: $3.50 ÷ 30 MPG = $0.1167, or 11.7 cents.
• Cost per 10 miles: 11.7 × 10 = $1.17.
• Cost per 100 miles: $11.67.
• A 250-mile road trip: 250 × 0.1167 = $29.18, or $58.35 round trip.
• A year of 12,000 miles: 12,000 × 0.1167 = $1,400.

Now change one variable. Bump the pump price to $4.50 and the same car costs 15.0 cents a mile, a year of driving jumps to $1,800, $400 more for the same miles. Drop to a 40 MPG car at $3.50 and the cost falls to 8.75 cents, or $1,050 a year. Notice that MPG and gas price pull in opposite directions: a 33% better MPG saves about the same as a 33% cheaper gallon.

Fuel cost per mile at a glance

Find your MPG down the left and the gas price across the top. Every cell is the fuel cost of one mile in cents.

Two rows worth reading together: at $4.00 a gallon, going from 20 MPG to 40 MPG halves your cost per mile from 20.0 cents to 10.0 cents. And at a fixed 30 MPG, the difference between $3.00 and $5.00 gas is 10.0 cents versus 16.7 cents per mile, a 67% swing driven entirely by the pump. National average prices move every week; the US Energy Information Administration tracks them, and in late 2026 the national average for regular was about $4.35 a gallon.

Fuel is only part of what a mile costs

Fuel is the visible cost, but it is not the whole cost of driving. The IRS publishes a rate that bundles everything a business mile costs, and for 2026 it is 72.5 cents per mile from January 1 to June 30 and 76 cents per mile from July 1 to December 31. Of that, the IRS treats 35 cents per mile as depreciation alone. Compare that with 11.7 cents of actual fuel and the point is obvious: gas is roughly a sixth of what a mile costs.

Those non-fuel figures are estimates that vary hugely by car, age and state, but the ordering is stable: depreciation usually costs more per mile than gasoline does. The IRS standard mileage rates page is the easiest authoritative reference for an all-in per-mile number, and it is updated every year.

How to lower your cost per mile

You control two of the three levers, the price you pay per gallon and how efficiently you drive. The third, distance, is often the biggest.

• Buy cheaper gas. A 30-cent spread between stations is 1 cent per mile at 30 MPG, or $120 a year over 12,000 miles. Warehouse clubs and grocery-fuel programs are the usual winners.
• Drive slower. Fuel economy falls off sharply above 50 mph. Dropping from 75 to 65 mph can improve MPG by roughly 10 to 15%, which at $3.50 gas is about 1.5 cents per mile.
• Keep tires inflated. Under-inflated tires cost about 0.2% fuel economy per psi across all four tires, small, but free.
• Combine trips. A cold engine burns more fuel, so three short errands in one loop beat three separate starts.
• Reduce weight and drag. Roof racks and a trunk full of cargo both cost mileage at highway speed.

Worked example: a driver at 30 MPG and $3.50 gas who improves to 34 MPG saves 1.37 cents per mile, which is $164 a year over 12,000 miles. Combine that with buying gas 20 cents cheaper and the same driver keeps about $244 a year, no new car required.

MPG, gallons and the units that trip people up

Two unit traps make cost-per-mile answers come out wrong.

• Gallons vs litres. US prices are per US gallon (3.785 litres), not the imperial gallon used in the UK (4.546 litres). If you convert a UK figure, your cost per mile will be off by about 20%.
• MPG vs L/100km. The US and UK use miles per gallon, where higher is better. Most of the world uses litres per 100 kilometres, where lower is better. They are inverses, not proportional, doubling MPG halves L/100km, but adding 10 MPG is not the same as subtracting 10 L/100km.

Worked example: a car that does 30 MPG uses 100 ÷ 30 × 3.785 = 12.6 L/100km. Its cost per mile at $3.50 is 11.7 cents. Convert the same car to a UK-style figure and it looks like 36 imperial MPG, a different number for the same car, purely because the gallon is bigger. When you compare costs, keep the gallon and the mile on the same system, or the answer will not mean what you think.