Fuel cost
calculator.
Find what a drive will cost in gasoline, diesel or electricity. Use mpg, L/100 km, km/L or kWh/100 mi, price fuel by the gallon or liter, and split the cost of a round trip or a month of commuting.
Driving 250 mi uses 8.929 US gal of fuel, costing $27.68.
- Total cost
- $27.68
- Fuel used
- 8.929 US gal
- Distance driven
- 250 mi
- Fuel cost per mile
- $0.111
402.336 km × 8.40052 L/100 km ÷ 100 = 33.7983 L × 0.818933 per L = 27.68What a drive
really costs.
- Fuel used = distance ÷ fuel economy (or distance × L/100 km ÷ 100). Cost = fuel used × price.
- Units are converted exactly: 1 mile = 1.609344 km, 1 US gallon = 3.785411784 L, 1 UK gallon = 4.54609 L.
- A UK mpg figure is about 20% higher than a US mpg figure for the same car, because the UK gallon is larger.
- The result is the energy cost only, plus any tolls and parking you add. It leaves out wear, tires, insurance and depreciation.
How do you calculate the fuel cost of a trip?
Divide the distance by your fuel economy to get the fuel used, then multiply by the price. A 250-mile drive in a car that gets 28 mpg uses 250 ÷ 28 = 8.93 gallons. At $3.10 a gallon that is $27.68. For a round trip, double the distance.
gallons = miles ÷ mpg
cost = gallons × price per gallonHow do you calculate it with L/100 km?
L/100 km tells you how many liters the car uses for every 100 km, so multiply instead of dividing. A 240 km round trip at 6.5 L/100 km uses 240 × 6.5 ÷ 100 = 15.6 L. At €1.85 per liter that is €28.86, or €9.62 each for three people.
liters = km × (L/100 km) ÷ 100
L/100 km = 235.214583 ÷ mpg (US)How much does it cost to drive an electric car?
Multiply the distance by the car's energy use and your electricity price. The U.S. window sticker gives energy use in kWh per 100 miles, which says how many kilowatt-hours the car would use to travel 100 miles. A car rated at 30 kWh/100 mi uses 75 kWh for 250 miles; at $0.17 per kWh, that is $12.75. Public fast chargers usually cost much more per kWh than charging at home, so enter the price you will actually pay.
kWh = miles × (kWh/100 mi) ÷ 100
cost = kWh × price per kWhUS mpg, UK mpg and km/L
A US gallon is 3.785 L and a UK (imperial) gallon is 4.546 L, so the same car shows a higher mpg in the UK: 30 mpg (US) is 36.0 mpg (UK), 7.84 L/100 km and 12.75 km/L. Choose the unit your figure is quoted in, and the price unit your pump shows. The calculator converts between them, and the table under the result lists your economy in every unit.
Worked examples.
A road trip by car
250 miles one way, 28 mpg, gas at $3.10 per gallon.
8.93 gallons and $27.68.
Load this exampleA shared round trip in Europe
120 km each way, 6.5 L/100 km, fuel at €1.85 per liter, three people sharing.
15.6 L of fuel, €28.86 in total, €9.62 each.
Load this exampleA month of commuting
18 miles each way, 21 working days, 32 mpg, $3.10 per gallon.
756 miles, 23.6 gallons and $73.24 a month.
Load this exampleThe same road trip in an electric car
250 miles at 30 kWh/100 mi, charging at $0.17 per kWh.
75 kWh and $12.75.
Load this exampleUK mpg with fuel priced per litre
200 miles at 45 mpg (UK gallons), fuel at £1.40 per litre.
20.2 L of fuel and £28.29.
Load this exampleWhat this calculator
does not do.
- Your real fuel economy depends on how you drive and the conditions. According to fueleconomy.gov, aggressive driving can lower gas mileage by roughly 15% to 30% at highway speeds, and in cold weather (20°F) a conventional car’s city mileage is roughly 15% lower. Use your own measured average when you have one.
- It does not know today's fuel or electricity prices. Enter the price you expect to pay.
- It is not a full cost of ownership: maintenance, tires, insurance and depreciation are not included.
Common questions.
How do I work out my own mpg?
Fill the tank, reset the trip meter, drive normally, then fill up again. Divide the miles driven by the gallons needed to refill.
How do I convert mpg to L/100 km?
Divide 235.215 by the US mpg figure: 30 mpg is 7.84 L/100 km. For UK mpg, divide 282.481 instead.
How do I split gas money with friends?
Enter the whole trip, including tolls and parking, and the number of people. The calculator divides the total equally.
What is MPGe?
Miles per gallon equivalent: how far an electric car goes on the energy in one gallon of gasoline, which U.S. federal rules set at 33.705 kWh. A car using 30 kWh/100 mi gets 3370.5 ÷ 30 = 112 MPGe.
- U.S. eCFR, 40 CFR 600.002 (definitions) — one gallon of gasoline is equivalent to 33.705 kWh
- NIST Handbook 44 (2026), Appendix C: General Tables of Units of Measurement — exact mile and US gallon definitions
- NIST SP 811, Appendix B.8: Factors for units listed alphabetically — the imperial gallon is exactly 4.546 09 L
- fueleconomy.gov: Driving More Efficiently — effect of driving habits on mpg
- fueleconomy.gov: Fuel Economy in Cold Weather — effect of temperature on mpg and EV range
- fueleconomy.gov: Learn More About the Electric Vehicle Label — what MPGe and kWh/100 mi mean
Distances are converted to kilometers and fuel economy to liters per 100 km (or kWh per 100 km) with exact unit definitions, then multiplied by the price per liter or kWh. Our tests check hand-calculated trips in mpg, UK mpg, L/100 km, km/L and kWh/100 mi, round-trip and commute multipliers, cost splitting, and round-trip conversions between every economy unit.
Built and reviewed by CalculatorLab against the sources above; every worked example on this page is re-checked by our automated test suite before each release. How we build and check calculators. Found a problem? Tell us.