Gas or charging cost of a trip from distance, MPG or L/100 km and price, split per person
Estimates only, not financial advice. What you type stays on your device. Checked against sources on 1 Oct 2026.Divide the distance by your fuel economy and multiply by the fuel price. A 300-mile drive at 30 MPG uses 10 gallons, which costs $35.00 at $3.50 a gallon. Tick round trip to double it, set how many people share it, or switch to kWh and price per kWh for an electric car.
Choose the Car, "Gas / petrol / diesel" or Electric, and the Units you use.
Enter the "Distance, one way" and the "People sharing the cost".
Turn on Round trip if you drive back the same way.
Enter the Fuel economy, the price per gallon or litre you pay, and pick the Currency.
Read the cost, the Fuel used and the cost per mile or km, then press Share result.
The cost of a drive comes down to three numbers: how far, how much fuel the car uses for that distance, and what the fuel costs. This calculator takes them in whichever units your car and your country use, and gives the trip cost, each person's share and the cost per mile and per kilometre. Round trip doubles the one-way distance: 150 miles there and back at 25 MPG, with gas at $3.40, uses 12 gallons and costs $40.80.
Units. Choose miles with MPG and a price per U.S. gallon, kilometres with litres per 100 km, or kilometres with km per litre. Switching converts the figures already entered, so the trip stays the same trip. The conversions use the U.S. gallon of 231 cubic inches (3.785411784 litres) and the mile of 1.609344 km, both exact definitions in NIST Handbook 44. A UK MPG figure uses the larger Imperial gallon and is about 20% higher than the U.S. figure for the same car, so convert it to L/100 km before entering it.
MPG from a fill-up. Fill the tank, reset the trip meter, drive, and fill again: the distance divided by the fuel added is your real-world economy. Enter both and the page shows it as MPG, L/100 km and km/L, ready to use for the trip.
Electric cars. Enter the car's energy use per 100 miles or 100 km and your price per kWh. Some energy is lost between the socket and the battery while charging; if you know the share for your charger, add it and the cost is worked out on the energy drawn from the wall.
What it does not do. It does not look up today's fuel or electricity price, because those change daily and by station; enter the price you will pay. Tolls, parking, wear and tear and insurance are not included, and the split is even. The currency choice changes only the symbol shown; no exchange rate is applied. Everything runs in your browser.
Divide the distance by the car's miles per gallon to get the gallons used, then multiply by the price per gallon. A 300-mile drive at 30 MPG needs 10 gallons, and at $3.50 a gallon that is $35.00. Double it for a round trip, and divide by the number of people sharing the cost.
Divide 235.215 by the MPG figure. The constant is 100 times the litres in a U.S. gallon (3.785411784) divided by the kilometres in a mile (1.609344). So 30 MPG is 7.84 L/100 km and 25 MPG is 9.41 L/100 km. The same division works the other way, from L/100 km back to MPG.
Fill the tank to the top and reset the trip meter. Drive normally, then fill up again and note the gallons added. Miles driven divided by gallons added is the real MPG: 330 miles on 11 gallons is 30 MPG. Averaging several tanks gives a steadier figure than a single one.
Multiply the distance by the car's energy use and the electricity price. At 30 kWh per 100 miles, 300 miles takes 90 kWh, which costs $15.30 at 17 cents per kWh. Public fast chargers often cost several times the home rate, so enter the price you will actually pay.
No. A UK figure uses the Imperial gallon of about 4.546 litres, while the U.S. gallon is 3.785 litres, so the same car shows roughly 20% more miles per gallon in the UK. Enter a UK figure as L/100 km instead: divide 282.48 by the UK MPG to convert it.
No. The figure covers fuel or electricity only. Tolls, parking, tyres, servicing, depreciation and insurance all add to the real cost of driving, and the IRS standard mileage rate is one published estimate of that total. Add tolls and parking to the result yourself when splitting a road trip.
Rates and rules change; check the source before you rely on a figure.
Still stuck? Ask about Fuel Cost Calculator and anybody who knows can answer. No account needed.
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