Fuel Cost Calculator

Free Fuel Cost Calculator: quick fuel cost calculator for everyday decisions. No signup needed.

A fuel and trip cost calculator estimates the total fuel cost of a journey based on distance, vehicle fuel efficiency, and current fuel prices. It is useful for budgeting road trips, comparing the cost of driving vs other transport modes, calculating mileage reimbursement, and estimating vehicle running costs. With fuel prices fluctuating globally and the increasing availability of electric vehicles, the calculation also helps compare petrol or diesel running costs against EV charging costs for the same journey. Loan Payment Calculator and Mortgage Calculator extend this to full vehicle cost comparisons.

Fuel economy figures published by manufacturers are measured under standardised laboratory test conditions (WLTP in most markets) and typically exceed real-world consumption by 15–25% due to driving style, road conditions, load, and climate. Using your own measured fuel economy from actual receipts gives more accurate trip cost estimates than relying on manufacturer specifications.

Enter the trip distance in miles or kilometres.
Enter your vehicle's fuel efficiency in mpg or L/100km. Use your own measured economy if possible, or reduce the official WLTP figure by 15–20% for a realistic estimate.
Enter the current fuel price per litre or per gallon.
The calculator computes litres or gallons needed and multiplies by price to give total fuel cost.
For multiple passengers sharing fuel cost, divide the result by the number of passengers.
For business mileage reimbursement, compare the calculated fuel cost against your employer's or tax authority's approved rate to check you are being fairly compensated.

Fuel cost calculation formulas

Fuel used (litres) = Distance (km) × (consumption L/100km ÷ 100)

Fuel used (UK gallons) = Distance (miles) ÷ MPG (UK)

Note: 1 UK gallon = 4.546 litres; 1 US gallon = 3.785 litres. UK and US mpg figures for the same vehicle differ by approximately 20% due to this difference.

Total cost = Fuel used (litres) × Price per litre

Worked example: 400 km trip in a car using 7 L/100km at 1.60/litre. Fuel used = 400 × 7/100 = 28 litres. Cost = 28 × 1.60 = 44.80 for the journey (0.112/km fuel cost). Shared 4 ways: 11.20 per person.

Using your fuel cost result

Vehicle fuel economy benchmarks

Typical fuel economy ranges by vehicle type (real-world, not manufacturer WLTP): small city car approximately 5.5–7 L/100km (40–51 mpg); medium family car 7–9 L/100km (31–40 mpg); SUV/crossover 8–11 L/100km (26–35 mpg); large SUV or pickup 12–18 L/100km (16–24 mpg); hybrid approximately 4.5–6 L/100km (47–63 mpg); plug-in hybrid 2–5 L/100km (56–141 mpg on combined cycle); electric vehicle approximately 15–25 kWh/100km (4–6 miles/kWh). Real-world consumption typically runs 15–25% above manufacturer WLTP figures.

Everyday Life tips and best practices

Smooth, anticipatory driving — accelerating and braking gently — can improve real-world fuel economy by 15–30% compared to aggressive driving.
Tyre pressure affects fuel economy — under-inflation by 0.3 bar (4 PSI) increases fuel consumption by approximately 1% per PSI under-inflation; check pressures monthly.
Air conditioning increases fuel consumption by 5–15% — at lower speeds, opening windows is more efficient; at motorway speeds, AC and open windows are comparable.
Roof boxes and racks significantly increase aerodynamic drag — remove them when not in use to recover 5–15% fuel economy.
Compare rail or coach for long journeys — a full car of four passengers is often cheaper than four train tickets, but a solo driver may find public transport more economical.

Fuel accounts for approximately 30–40% of total vehicle running costs for an average driver — making it the largest variable cost component after depreciation.
Driving at 130 km/h vs 100 km/h increases fuel consumption by approximately 25–30% for most vehicles due to aerodynamic drag increasing with the square of speed.
An electric vehicle charged at home typically costs 60–75% less per kilometre than an equivalent petrol vehicle at current fuel and electricity prices in most markets.
Cold starts (engine below operating temperature) can increase fuel consumption by up to 40% for the first few kilometres — minimise short cold-start trips to optimise real-world economy.

Common mistakes to avoid

Confusing UK and US gallons — 1 UK gallon = 4.546 L vs 1 US gallon = 3.785 L; a US mpg figure is approximately 20% lower than the equivalent UK mpg for the same vehicle and consumption rate.
Using the WLTP official fuel economy figure without applying a real-world correction of 15–25% — the official figure is measured under controlled laboratory conditions.
Not accounting for motorway vs urban driving differences — motorway driving can be 20–40% more fuel-efficient than stop-start urban driving for the same vehicle.
Forgetting toll costs, parking, and congestion charges when comparing drive vs public transport for city journeys — these can significantly change the cost comparison.

Fuel economy figures referenced here are based on manufacturer-published WLTP (Worldwide Harmonised Light Vehicle Test Procedure) ratings, which are used in Europe, UK, and many other markets. US vehicles use EPA ratings, which are typically closer to real-world figures. Actual fuel consumption varies by driving conditions, load, speed, and vehicle maintenance. Mileage reimbursement rates for business travel are set by each country's tax authority — consult your national tax office for current approved rates. Fuel pricing is set by market forces and taxes that vary by country and region.