Fuel Cost Calculator
Updated · By the CalculatorDash editorial team · How we check our maths
Quick answer
Trip fuel cost = distance ÷ fuel economy × fuel price. Driving 350 miles in a car that does 30 mpg at $3.40 a gallon uses about 11.7 gallons and costs about $40, or $80 for the round trip.
How this calculator works
Fuel cost depends on three things: how far you drive, how much fuel your vehicle uses for that distance, and what you pay for the fuel. The calculator handles the four common ways of measuring economy: US miles per gallon, UK miles per gallon (a larger gallon, so higher numbers), litres per 100 km used in Europe, Canada and Australia, and km per litre used in India.
Real-world economy is usually lower than the official figure, especially at motorway speeds, with roof boxes, heavy loads or air conditioning running. If your car shows an average consumption on the dashboard, use that.
For a commute, enter the daily distance and multiply the result by working days. For an electric car, use the electricity cost calculator with your car's kWh per 100 miles or km.
The formula
- US/UK mpg
- fuel = distance ÷ mpg (UK gallons are converted to litres: × 4.546)
- L/100 km
- fuel = distance × L/100km ÷ 100
- Cost
- fuel × price per unit
Worked example
350 miles each way is 700 miles round trip. At 30 mpg that's 23.3 gallons; at $3.40 a gallon the trip costs about $79.33, or 11.3 cents a mile.
Tips
- 01Keep tyres at the recommended pressure; under-inflation can cut economy by several percent.
- 02Smooth acceleration and steady speeds save more fuel than any additive.
- 03Fuel prices vary along a route; filling up before motorway services usually saves money.
Frequently asked questions
How do I calculate fuel cost for a trip?
Divide the distance by your fuel economy to get the fuel used, then multiply by the fuel price.
How do I convert mpg to L/100 km?
L/100km = 235.2 ÷ US mpg, or 282.5 ÷ UK mpg.
Why is my UK mpg higher than US mpg?
A UK (imperial) gallon is 4.546 litres and a US gallon is 3.785 litres, so the same car shows about 20% more miles per UK gallon.