Fuel Cost Calculator is a specialized tool for estimating journey expenses and vehicle efficiency. Planning a road trip or calculating fleet costs requires knowing three things: how far you are going, how efficiently your vehicle uses fuel, and what fuel costs at the pump. This petrol cost calculator handles all unit combinations - imperial (MPG, miles) and metric (L/100km, km/L, kilometres) - and shows the total cost alongside the litres or gallons required.
MPG (miles per gallon): higher is better. US gallon = 3.785 L; UK imperial gallon = 4.546 L. L/100km (litres per 100 kilometres): lower is better - the European standard. km/L: higher is better. This journey cost tool helps you convert between systems: MPG (imperial) = 282.5 ÷ L/100km. MPG (US) = 235.2 ÷ L/100km. A car rated at 7 L/100km = ~40 MPG (US) ≈ 33 MPG (UK).
The UK and US gallon are different volumes. 1 UK (imperial) gallon = 4.546 litres; 1 US gallon = 3.785 litres. A car rated at 40 MPG in the UK is actually more fuel-efficient than a US car rated at 40 MPG - because the UK gallon is larger.
Double the one-way distance before calculating, or multiply the one-way result by 2. Make sure you use the return distance if the route is asymmetric (e.g. different road or elevation).
Add them manually to the fuel cost result. This calculator covers fuel only - total trip cost includes accommodation, food, tolls, and parking depending on your journey.
EVs are rated in MPGe (miles per gallon equivalent) - an EPA unit comparing energy consumption to gasoline. For actual cost calculation, use kWh/100km or miles/kWh from the vehicle's spec sheet and your electricity tariff per kWh instead.
For more utility tools, explore our Unit Converter, Compound Interest Calculator, and Calorie Calculator. This Fuel Cost Calculator is updated with the latest average fuel price estimates for accurate planning.