Fuel Cost Calculator
Work out the fuel cost of one trip or of your regular driving per week, month or year — in MPG (US or UK), L/100 km, km/L or gallons per 100 miles — with fuel used, cost per mile or km, fill-ups and a side-by-side with another car.
How it works
Fuel used = distance ÷ MPG (or km × L/100 km ÷ 100, km ÷ km/L, miles × gal/100 mi ÷ 100) · Fuel cost = fuel used × price · Round trip = 2 × one way · Yearly distance = daily distance × driving days × 52.14 weeks (or weekly × 52.14, monthly × 12) · Monthly cost = yearly cost ÷ 12
Fuel cost is the fuel you burn times what you pay for it. Divide the distance by your fuel economy to get gallons (or multiply kilometres by litres per 100 km), then multiply by the pump price. Pick “One trip” for a single drive, with an optional round trip, or “Regular driving” to turn a daily, weekly or monthly distance into a weekly, monthly and yearly fuel bill — a daily distance counts only the days you drive. Fuel economy can be typed as US or UK miles per gallon, litres per 100 km, kilometres per litre or gallons per 100 miles; the price follows the unit (per gallon or per litre), and the calculator converts so every figure stays consistent. A UK gallon is 4.546 litres against 3.785 for a US gallon, so 33.6 MPG (UK) is the same car as 28 MPG (US). Optional extras compare the bill with another car, show how far a tank goes and how many fill-ups you need, and estimate the CO₂ from the fuel. The price and economy tables show how much the answer moves if fuel gets dearer or the car does worse loaded up. For carpool splits, tolls, extra stops or an electric car, the fuel trip cost calculator handles the whole trip.
Worked example
A 300-mile trip in a car that gets 28 MPG needs 300 ÷ 28 = 10.71 gallons. At $3.50 a gallon that is $37.50 one way, or $75.00 round trip — $0.125 per mile. For regular driving, 30 miles a day on 5 days a week is 30 × 5 × 52.14 = 7,821 miles a year: 279.3 gallons, or $977.68 a year ($81.47 a month). A car doing 40 MPG would spend $684.38 on the same miles, $293.30 a year less.
Sources: fueleconomy.gov — Trip Calculator and fuel economy data (US DOE / EPA) · US EPA — Greenhouse gas emissions from a typical passenger vehicle (8,887 g CO₂ per gallon of gasoline)
Frequently asked questions
How do I work out my monthly fuel cost?
Pick “Regular driving”, enter how far you drive per day, week or month, and your fuel economy and price. A daily distance is multiplied by your driving days and 52.14 weeks to get a year; the monthly cost is the yearly cost divided by 12, so months of different length average out.
How do I convert L/100 km or km/L to MPG?
MPG (US) = 235.21 ÷ L/100 km, and MPG (US) = km/L × 2.352. UK MPG is 1.201 times the US figure because the imperial gallon is bigger. You do not need to convert: choose the unit your car uses and the results row “Your economy in other units” shows the rest.
Does highway or city driving change this?
Yes — use the economy that matches the driving. Highway trips usually beat the combined rating, while city stop-and-go, short trips, heavy loads and cold weather drag it down. The “better or worse” table shows how much a 10–20% change in economy moves the cost.
How much would a more efficient car save me?
Open “More options” and enter the other car’s fuel economy in the same unit. The calculator shows its fuel cost and the difference — per trip, or per year for regular driving — plus a chart of the costs side by side. Weigh the saving against any difference in price, insurance and maintenance.
How do I split fuel cost with passengers?
Divide the total fuel cost by the number of people sharing the ride. The fuel trip cost calculator does this directly and also adds tolls, parking and extra stops before splitting.
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This calculator is for educational purposes. Double-check important results before acting on them.