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Trip Fuel Cost Calculator

Enter trip distance, your car’s fuel economy, and the price at the pump. See how much fuel you need and what the trip will cost — metric (L/100km) or imperial (MPG).

Calculate

Measurements convert when you switch units

km
L/100km
$

Updates as you type

Result

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The formula

Fuel used equals distance scaled by economy. Metric uses litres per 100 km; imperial divides miles by MPG. Cost is fuel volume × price per litre or gallon.

Metric: Litres = (km ÷ 100) × L/100km · Cost = Litres × Price/L · Imperial: Gallons = mi ÷ MPG · Cost = Gallons × Price/gal

Worked example

  1. 310 mi, 36 MPG, $3.50/gal (imperial) — or metric: 500 km, 6.5 L/100km, $1.85/L
  2. Metric litres = (500 ÷ 100) × 6.5 = 32.5 L
  3. Cost = 32.5 × 1.85 = $60.13

Result: 32.5 L · $60.13

How trip fuel cost is calculated

This planner uses a known economy figure and trip length — unlike a fill-up average based on litres already burned.

Metric vs imperial

In metric mode, economy is L/100km (lower is better). Fuel = distance_km / 100 × L/100km. In imperial mode, economy is US MPG and fuel = miles ÷ MPG.

Price and currency

Multiply fuel volume by the price you enter. Currency formatting follows the page setting. Tolls, parking, and oil are not included.

What we do not model

No elevation, roof boxes, traffic mix, or cold-start penalties. Use a realistic average economy for your route, not only the WLTP sticker.

Interesting facts

Plan with a buffer

Real trips often use 5–15% more fuel than highway sticker figures once you add hills, wind, and city segments.

L/100km vs MPG

They move in opposite directions: better efficiency lowers L/100km and raises MPG. This tool switches interpretation with the unit toggle.

Price volatility

Pump prices change by day and corridor. Recalculate with the price you expect at your next fill-up stops.

Hybrids on long trips

Highway economy can differ from city hybrid ratings — use a trip-matched average when possible.

Frequently asked questions

Multiply distance by your economy (L/100km or ÷ MPG), then multiply litres or gallons by the fuel price. This calculator does that in one step.

Your fill-up average is usually closer to real costs. WLTP is a standardized label, not a guarantee for a mountain or winter route.

Imperial mode uses US gallons (≈ 3.785 L), matching US MPG. UK imperial gallons are larger.

No — only fuel volume × pump price. Add tolls and parking separately to your trip budget.

Fuel economy works backward from distance and fuel already used. Trip fuel cost plans ahead from a known economy and distance.

References

  1. FuelEconomy.gov — U.S. Department of Energy / EPA Official U.S. fuel-economy ratings and trip tools.
  2. WLTP — European Commission EU vehicle labelling test procedure.