Fuel cost is the fuel a trip burns multiplied by the pump price. In US units, divide miles by mpg to get gallons; in metric, multiply kilometres by L/100 km and divide by 100 to get litres. A 300-mile drive at 30 mpg uses 10 gallons, which at $3.50 a gallon costs $35.00.
Commuters comparing a new job location, families budgeting a road trip and small businesses pricing a delivery run all need the same number: how much fuel the drive will cost. Enter the distance, your car's fuel economy and the current pump price, choose US or metric units, and tick the round-trip box if you are coming back the same way. The result shows the total spend, the fuel burned, the distance counted and the cost per 100 miles or kilometres, so two cars or two routes can be compared on the same footing. The figure assumes your rated or measured average economy holds for the whole trip; heavy loads, roof boxes, mountain roads, air conditioning and sustained motorway speeds can push real consumption 10–25% higher.
US uses miles, miles per gallon and price per gallon; metric uses kilometres, litres per 100 km and price per litre.
Type the one-way distance and your car's average fuel economy, ideally from your own fill-up records.
Use the pump price per gallon or litre in your own currency.
The checkbox doubles the distance for an out-and-back journey; the total cost and fuel update straight away.
Result Fuel cost: 35.00
Fuel used: 10 gal
Distance driven: 300 mi
Cost per 100 mi or km: 11.67
A 300-mile drive in a car that averages 30 mpg burns 10 gallons, so at $3.50 a gallon the fuel bill is $35.
Result Fuel cost: 58.50
Fuel used: 32.5 L
Distance driven: 500 km
Cost per 100 mi or km: 11.70
Going out and back doubles the distance to 500 km; at 6.5 L/100 km that is 32.5 litres, or 58.50 at 1.80 per litre.
Result Fuel cost: 130.91
Fuel used: 40.91 gal
Distance driven: 900 mi
Cost per 100 mi or km: 14.55
900 miles at 22 mpg uses about 40.9 gallons; at $3.20 a gallon the trip costs about $130.91 in fuel.
US: cost = (distance ÷ mpg) × price per gallon. Metric: cost = (distance × L/100 km ÷ 100) × price per litre.
distancempgL/100 kmpriceThe calculator first finds how much fuel the trip consumes, then multiplies by the price. Miles per gallon is a distance-per-fuel figure, so distance is divided by it; litres per 100 km is a fuel-per-distance figure, so distance is multiplied by it and divided by 100. Cost per 100 miles or kilometres is the total cost divided by the distance, times 100.
Fill the tank, reset the trip meter, drive normally, then refill. Divide the miles driven by the gallons added for mpg, or multiply litres by 100 and divide by kilometres for L/100 km. Averaging three or four tanks smooths out pump shut-off differences.
Divide 235.215 by the US mpg figure. A car rated at 30 mpg uses about 7.84 L/100 km. For UK imperial mpg, divide 282.481 by the figure instead.
Yes. The result is in whatever currency you entered the fuel price in. The US option shows a dollar sign on the price field, so drivers paying per litre in euros or pounds should switch to the metric option.
Rated economy comes from standard test cycles. Speeds above about 60 mph, cold starts, short trips, heavy cargo, roof racks and air conditioning all raise consumption. Cold weather alone can cut economy by 15% or more on short journeys.
Divide the total by the number of people sharing. A $35.00 trip shared by four people is $8.75 each. Some groups split by seat including the driver, others exclude the driver who supplies the car.
It puts different cars or prices on the same scale. At 30 mpg and $3.50 a gallon a car costs $11.67 per 100 miles; at 22 mpg the same fuel costs $15.91 per 100 miles, which is the gap you pay on every trip.
Using this tool in an assignment, article or report? Copy a citation, or a link for your website.
Tools Directory Editorial Team. (2026, October 21). Fuel Cost Calculator. Tools Directory. Retrieved October 26, 2026, from https://tools.milunir.com/automotive/fuel-economy-and-running-costs/fuel-cost-calculator/
Tools Directory Editorial Team. “Fuel Cost Calculator.” Tools Directory, 21 Oct. 2026, https://tools.milunir.com/automotive/fuel-economy-and-running-costs/fuel-cost-calculator/. Accessed 26 Oct. 2026.
Tools Directory Editorial Team. “Fuel Cost Calculator.” Tools Directory. Last modified October 21, 2026. Accessed October 26, 2026. https://tools.milunir.com/automotive/fuel-economy-and-running-costs/fuel-cost-calculator/.
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