Fuel Cost Calculator

Price a trip in litres or gallons by L/100 km, km/L or US MPG: total cost, fuel needed, cost per kilometre or mile, per-person split and car comparison.

All calculations happen locally in your browser. Your distances and fuel prices never leave your device.

Distance unit
Fuel economy shown as
/ L
Total fuel cost
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Fuel needed
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Cost per km
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Cost per person
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The price label follows the economy unit: MPG implies price per US gallon (3.785 L), the other modes imply price per litre.

The currency selector only changes the display symbol — no exchange-rate conversion is applied. To convert an amount, use the currency converter..

Estimates only — real fuel consumption varies with driving style, load and conditions.

How It Works

Fuel cost is one product: distance × consumption × price. The only complication is that the world measures consumption three different ways, so the tool converts everything internally to litres per 100 km before multiplying.

The three conventions
L/100 km (mainstream Europe and China) reads lower-is-better: litres burned per 100 kilometres. km/L (India and some others) reads higher-is-better: distance per litre. US MPG (miles per US gallon) also reads higher-is-better but hides two unit changes at once. The conversions used here are exact: L/100 km = 100 ÷ (km/L), and L/100 km = 235.2145 ÷ MPG, where 235.2145 = 3.785411784 litres/gallon × 100 ÷ 1.609344 km/mile.
Why the US and Europe confuse each other
Distance per fuel and fuel per distance are reciprocals, and reciprocal intuition fails: going from 50 to 40 MPG saves far less fuel than going from 20 to 16.7 MPG, even though both look like "10 MPG". The 235.2145 constant turns every US mpg into L/100 km and makes the arithmetic comparable. (The tool uses US MPG; UK imperial MPG would need 282.481 as its constant, and it is a different gallon.)
Worked example
A 500 km trip in a car rated 7 L/100 km with fuel at 1.75 per litre: consumption = 500 ÷ 100 × 7 = 35 L ≈ 9.2 US gallons, total cost = 35 × 1.75 = 61.25, which is 0.1225 per km — and 33.6 US MPG if you prefer that unit. Two passengers split it 30.625 each.

Frequently Asked Questions

Do A/C, idling and load actually change the numbers?

Yes, and not marginally: aggressive acceleration, sustained high speed, heavy loads, cold weather and heavy A/C use can plausibly shift real consumption by 15% or more in either direction, and city stop-and-go driving differs from highway cruising. The figure this tool gives you is a driving-style-independent arithmetic result for the economy number you enter — treat it as a midpoint, not a quote.

Can I use this to price an electric car?

Not properly — an EV is metered in kWh per 100 km and priced per kWh, with charging curves and regenerative braking that no fuel-conversion factor captures. This tool is for liquid fuels only; there is a separate electricity calculator for kWh-based costs, but it estimates appliances, not drivetrains.

Why is the US MPG number not comparable to the UK MPG number?

Because a US gallon is 3.785 litres and an imperial gallon is 4.546 litres, so the same car reads about 20% higher on UK mpg than on US mpg. This calculator uses US gallons only, and says so on the label — mixing the two is one of the most common fuel-math errors.

Are tolls, parking and maintenance included?

No — this is fuel cost only. Tolls, parking, tyre wear and servicing can meaningfully change the real cost of a trip, so add them separately if you are comparing routes or car ownership.

Is anything uploaded to a server?

No. The conversions between L/100 km, km/L and MPG and all cost math run locally in your browser with plain JavaScript. Your distances and prices never leave your device, and there is no account and no network request attached to a calculation.