Fuel Cost Calculator

Fuel a journey needs and what it costs, in mpg, km/L or L/100km.

Trip fuel cost
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Fuel needed
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Cost per km
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Cost per mile
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Each person pays
How this works
Litres needed = distance (km) ÷ efficiency (km/L) Cost = litres × price per litre
ConversionValue
1 US gallon3.785 litres
1 UK gallon4.546 litres
1 mile1.609 km
mpg (US) → km/L× 0.4251
mpg (UK) → km/L× 0.3540
km/L → L/100km100 ÷ km/L
  • US and UK mpg are not the same figure — a UK gallon is 20% larger, so UK mpg always looks better.
  • L/100km falls as efficiency improves; km/L and mpg rise. They move in opposite directions.
  • Real consumption is usually 10-20% worse than the manufacturer's figure, and worse again in cold weather, in traffic, or above 110 km/h.

Currency

  • Amounts follow the currency selected above.
How do I work out fuel cost for a trip?

Divide the distance by your fuel efficiency to get the fuel needed, then multiply by the price per litre or gallon.

Is US mpg the same as UK mpg?

No. A UK gallon is 4.546 litres against the US 3.785, so the same car shows about 20% higher mpg on UK figures.

Why does my real economy differ from the official figure?

Official tests are laboratory cycles. Cold starts, short journeys, traffic, roof racks, air conditioning and speeds above 110 km/h all reduce it, typically by 10-20%.

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