Fuel used and cost
Enter trip distance, fuel economy, and the price you pay at the pump. UK uses miles and litres (economy as UK MPG or L/100 km). Tick round trip to double the distance.
How trip fuel cost is estimated
Distance × economy × pump price
Enter how far you will drive, how efficiently the vehicle uses fuel, and the price you pay per litre at the pump. The calculator estimates litres required and total fuel cost. UK-style inputs use miles with economy as UK MPG or L/100 km. Tick round trip to double the distance.
Formulas (conceptual)
- From L/100 km: litres ≈ distance_km × (L/100 km) ÷ 100
- From UK MPG: convert miles and MPG into litres using the imperial gallon size
- Cost ≈ litres × price per litre
Worked example
A 120 mile one-way trip in a car averaging 45 UK MPG uses fewer litres than the same trip at 35 UK MPG. At £1.45/L, the cost difference is often several pounds even before a return ticketed journey doubles the fuel.
Real-world variance
Cold starts, hills, speed, cargo, and air-con move economy away from brochure figures. Motorway MPG may beat city MPG or the reverse depending on the vehicle. Use a slightly pessimistic economy for budgeting.
Common mistakes
- Mixing US MPG with UK MPG — gallons differ; see Travel.
- Forgetting the return trip.
- Using petrol price on a diesel car’s budget (or the reverse).
FAQs
- Can I enter kilometres?
- Convert distance first with Travel, or use economy in L/100 km with matching distance units as the page expects.
- Does this include charging for EVs?
- No — it models liquid fuel cost only.
Related: Travel, Liquids, Unit Price.
Last updated: July 2026