Fuel Cost Calculator

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📖 About This Tool

The UK presents a particular quirk: fuel is sold by the litre, but car efficiency is still officially quoted in miles per gallon - a unit that references a measure nobody uses at the pump. This is a legacy of the UK's partial metrication: fuel switched to litres in the 1980s, but road signs and speed limits stayed in miles. The calculator handles the conversion between miles, litres, and gallons automatically, so you just enter the figures as you find them.

The CO2 estimates use standard emission factors: petrol emits roughly 2.31 kg of CO2 per litre burned, and diesel 2.68 kg. Electric vehicle emissions are calculated using the UK grid average carbon intensity, which has fallen sharply as renewable generation has increased - an electric car charged on the 2024 grid produces roughly a third of the per-mile emissions of an equivalent petrol car, though this varies by time of day and location.

How to Use

• • Choose your region (UK or US) to pre-fill units and typical fuel prices.
• • Enter your distance, fuel efficiency (MPG or L/100km), and current fuel price.
• • Add the number of passengers to split the cost automatically.
• • Toggle Compare Two Cars to see side-by-side cost comparisons between a more and less efficient vehicle on the same trip.
• • CO₂ emissions are estimated based on fuel type and distance using standard emission factors.

Fuel Efficiency Reference