Fuel Cost Calculator
Work out the fuel cost of a one-off journey, your weekly commute, or your annual mileage. Enter the distance in miles, your car's MPG, and the current pump price in pence per litre — the calculator handles the unit conversion and returns the cost. EV drivers can switch to a per-mile electricity figure based on their tariff and home-charging efficiency.
How is this calculated?
Litres used = miles ÷ MPG × 4.546 (litres per imperial gallon). Cost = litres × price per litre. The calculator accepts pence-per-litre as commonly displayed at UK pumps. For EVs, energy used = miles × kWh-per-mile (typically 0.25–0.35 for most UK EVs in real-world conditions), then multiplied by your electricity tariff in pence per kWh. Public rapid charging is materially more expensive than home charging on an off-peak EV tariff.
Frequently Asked Questions
How do I find my car's true MPG?
Manufacturer figures (WLTP) are useful for comparison but routinely 15%–25% higher than real-world. Calculate your own by topping up the tank, recording the trip mileage, and dividing miles travelled by litres pumped on the next refill (then multiply by 4.546 to convert litres to imperial gallons).
Are EVs cheaper to run?
Significantly, if you charge at home on an off-peak EV tariff at around 7–10p/kWh — running costs are often 2–4p per mile compared with 12–18p per mile for a petrol equivalent. Relying on public rapid chargers at 60–80p/kWh narrows or eliminates the gap, so home charging access is the swing factor.
How much fuel duty and VAT am I paying?
Fuel duty has been 52.95p per litre on petrol and diesel for several years, plus 20% VAT applied to the duty-inclusive price. On a £1.45/litre pump price that's roughly 53p of duty and 24p of VAT — well over half the price is tax going to HMRC.
Does driving style really make a difference?
Yes — typically 10%–25%. Steady motorway speeds (60–65 mph rather than 75+), gentle acceleration, anticipating lights, properly inflated tyres, and not lugging around an empty roof rack all add up. Short cold-start journeys are the worst case for petrol cars; the engine never reaches efficient operating temperature.
Last updated: May 2026 · Rates sourced from HMRC