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Fuel Cost Calculator

How much will that road trip cost in fuel? Distance, MPG, and price per gallon — answered.

Unit

Result —

About this calculator

Before you plan a road trip — or quote a delivery — you need to know what the fuel will actually cost. This calculator handles both US (miles, MPG, dollars per gallon) and metric (kilometres, L/100km, currency per litre), so it works for cross-country trips, daily commutes, and freight estimates alike.

How it works

The math is straightforward. In metric: fuel needed (litres) = distance (km) × consumption (L/100km) / 100. In imperial: fuel needed (gallons) = distance (miles) / fuel economy (MPG). Total cost = fuel needed × price per unit.

Use real-world fuel economy, not the EPA or WLTP sticker number. Most modern cars achieve about 80-85% of their advertised efficiency on average — and significantly less in city traffic, with a heavy load, in cold weather, or with a roof rack adding aerodynamic drag.

For a round trip, double the one-way distance. The calculator computes whatever distance you enter; if you're going there and back, enter the round-trip total.

If you're trying to decide between driving and flying or taking the train, also factor in tolls, parking, wear-and-tear (the IRS standard mileage rate of 67 cents per mile in 2026 is a decent rough proxy), and time. Pure fuel cost almost always favours driving for short trips and longer trips with multiple passengers.

Formula

Metric:  litres = (distance_km × L_per_100km) / 100
Imperial: gallons = distance_miles / mpg

total_cost = fuel_needed × price_per_unit
cost_per_unit_of_distance = total_cost / distance

Examples

300-mile trip, 30 MPG, $3.50/gallon

A 300-mile trip in a 30-MPG car at $3.50/gallon costs $35 in fuel — about 12 cents per mile.

Result: Fuel needed 10 gallons — Total cost $35 — Cost per mile $0.117

500 km trip, 7 L/100km, €1.75/L

A 500-km drive at 7 L/100km and €1.75 per litre costs €61.25 in fuel.

Result: Fuel needed 35 L — Total cost €61.25 — Cost per km €0.123

Frequently asked questions

Should I use the EPA / WLTP rating? +
It's a starting point, but real-world fuel economy is usually 10–20% worse than the official rating. Use your actual observed MPG/L per 100km if you have it (most modern cars display lifetime average).
How do I convert MPG to L/100km? +
L/100km = 235.21 / MPG. So 30 MPG ≈ 7.84 L/100km. Note that MPG is a ratio (higher = better) while L/100km is an inverse (lower = better).
Does it work for electric vehicles? +
Not directly — EV consumption is measured in kWh/100km or miles/kWh, and pricing is per kWh. You can adapt the math: treat your kWh/100km as 'consumption' and your $/kWh as 'price'.
How much does highway vs city driving change things? +
Most non-hybrid cars get 20–30% better fuel economy on the highway than in city traffic. Hybrids are the exception — they're often more efficient in city driving thanks to regenerative braking.
Should I count tolls and wear-and-tear? +
For an accurate per-mile cost: yes. The IRS 2026 standard mileage rate of 67¢ covers fuel, depreciation, maintenance, insurance and registration — use it as a rough total cost-per-mile figure.

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