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Fuel Cost Calculator

What this does

Work out the fuel needed and total cost of any trip, then split the cost between passengers.

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Calculator inputs

How to use it

Using the fuel cost calculator

  1. 01

    Pick your units

    Choose imperial for miles/mpg/$-per-gallon, or metric for kilometers/L-per-100km/$-per-liter.

  2. 02

    Enter the trip details

    Add the one-way or round-trip distance, your vehicle’s efficiency and the current fuel price.

  3. 03

    Split if needed

    Set the number of people sharing the cost to see what each person owes.

Good to know

Where road-trip money actually goes

Fuel is usually the second-largest road-trip expense after lodging. Because cost scales linearly with distance, doubling the trip doubles the bill; but efficiency improvements help too: trading 20 mpg for 25 mpg cuts fuel use by 20% on the same route.

Metric versus imperial efficiency

The two conventions run in opposite directions: higher mpg is better, while lower L/100km is better. Convert between them mentally with 235.215 ÷ mpg ≈ L/100km, or use our dedicated fuel economy converter.

Fair splitting

Even splits ignore who drove, but they keep group trips friendly. If one person lends the car, splitting fuel only; not wear, insurance or depreciation; is the customary courtesy.

How it's calculated

The math behind this calculator

Imperial: gallons = miles ÷ mpg Metric: liters = km × L/100km ÷ 100 Total cost = fuel needed × price Per person = total ÷ people

In imperial mode the trip distance divided by your car’s mpg gives gallons burned; in metric mode, kilometers multiplied by L/100km over 100 gives liters. Multiplying fuel by its price gives the trip cost, which we divide evenly across passengers.

Assumptions & limitations

  • Efficiency stays constant across the trip; highway beats city driving.
  • Price is the same at every fill-up.
  • The per-person split divides evenly with no rounding up.

Worked example

A 500-mile trip in a 25 mpg car at $3.50 per gallon burns 20 gallons and costs $70.00; just $70.00 each when traveling solo.

FAQ

Frequently asked questions

Should I use my car’s rated mpg?
Real-world driving usually lands 10–15% below the window sticker, mostly city driving and heavy loads. Use your own fill-up math via the gas mileage calculator for accuracy.
Does this include tolls or wear?
No; fuel only. For an employer-grade rate that covers depreciation and insurance, see the mileage reimbursement calculator.
What about electric cars?
Use the electricity cost calculator instead: treat kWh consumed as “fuel” and your price per kWh as the energy price.

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