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Free Fuel Cost Calculator

Estimate the fuel cost of any trip from distance, vehicle efficiency, and fuel price. Supports mpg, L/100km, and km/L, plus round trips and cost splitting.

Works offline once loaded

miles per gallon (mpg)

per gal
Estimated fuel cost
11.67
in your fuel-price currency
3.33 gal for 100 mi
Estimated fuel cost: 11.67

πŸ’‘ Amounts are shown in your fuel-price currency β€” the number is currency-agnostic, so it works for $, Β£, €, or any other. Real-world consumption varies with speed, terrain, load, and weather, so treat this as a close estimate.

Common uses

  • Estimate Road Trip Fuel CostBudget the fuel for a long drive from distance, mpg, and gas price.
  • Split Gas Money Between PassengersFairly divide fuel cost among everyone in the car for a trip.
  • Calculate Your Commute Fuel CostFind out what driving to work really costs per day, week, or month.
  • Fuel Cost in Litres & KilometresCalculate cost using L/100km or km/L and price per litre.
  • Compare Fuel Costs Between CarsSee how much a more efficient vehicle would save on the same trips.

How It Works

All calculation happens instantly in your browser using a hand-written arithmetic formula β€” no library, no server, no network request. You enter distance, vehicle efficiency, and fuel price; React's useMemo hook recomputes the result on every keystroke.

  1. 1
    Unit normalisation
    Before any arithmetic, the tool converts your inputs into a consistent unit system. If your efficiency is in mpg, distance is converted to miles (multiplying by 0.621371 if you entered kilometres). If your efficiency is in L/100 km or km/L, distance is converted to kilometres instead.
  2. 2
    Fuel volume calculation
    The core formula is straightforward: for mpg, fuel used = distance_in_miles / mpg, giving gallons. For L/100 km, fuel used = (distance_km / 100) Γ— efficiency value, giving litres. For km/L, fuel used = distance_km / efficiency value. No lookup table β€” just direct arithmetic.
  3. 3
    Cost and split projection
    Total cost = fuel volume Γ— price per unit. If you enable round trip, distance is doubled before the calculation. If you enter a passenger count, the total is divided equally. If you enter trips per week, the tool multiplies the per-trip cost by that number, then by 52/12 for monthly and 52 for yearly, projecting your commute cost across three time horizons.
  4. 4
    Second vehicle comparison
    When you enable the comparison mode, the same fuel volume formula runs a second time with the alternative efficiency value, using identical distance and price inputs. The cheaper vehicle is highlighted, and if you also provided a trips-per-week figure, the annualised saving between the two vehicles is shown.

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Frequently Asked Questions