Fuel Cost Calculator

Plan a trip's fuel budget: enter the distance, your vehicle's efficiency and the fuel price. In US mode efficiency is miles per gallon and price is per gallon; in metric mode efficiency is litres per 100 km and price is per litre.

Real-world efficiency varies with speed, load, terrain and weather, so treat the result as a planning estimate and keep a margin on long trips. If your car quotes km/L instead of L/100km, convert with L/100km = 100 ÷ km/L.

The formula

US: Fuel = Distance ÷ MPG · Metric: Fuel = Distance × (L/100km) ÷ 100; Cost = Fuel × price

Worked example

A 300-mile trip at 30 mpg uses 10 gallons — $36.00 at $3.60 a gallon.

The example is pre-loaded in the result panel — press Calculate with your own numbers to replace it.

Frequently asked questions

How do I convert km/L to L/100km?

L/100km = 100 ÷ km/L. A car doing 15 km/L uses 6.67 L/100km. Enter 6.67 in metric mode.

Should I use the manufacturer's mpg figure?

It is a reasonable starting point, but highway driving at high speed, roof boxes and cold weather can cut real efficiency by 10–20%. Lower the figure slightly for a conservative budget.

Category: Everyday Life calculators

Sources & methodology

This calculator applies the formula shown on this page exactly as written, using the standard definitions for its inputs. Results are computed from the values you enter — no data is stored — and are rounded only for display.

Content last reviewed 2026-10-21 by CalcHub Editorial.

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Fuel needed (gallons or litres)	10.00
Trip fuel cost	$36.00

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