How it works
Fuel cost depends on three things: how far you drive, how much fuel your car uses, and the price of fuel. Fuel economy is written three ways around the world, and the calculator accepts all of them, with distances in miles or kilometres:
- Miles per gallon (mpg) — used in the United States; enter the price per US gallon. Higher is better.
- Litres per 100 km (L/100 km) — used in Europe and on many car spec sheets. Lower is better.
- Kilometres per litre (km/L) — common in Egypt, the Gulf and India. Higher is better.
Worked example. A 450 km trip in a car that uses 8 L/100 km, with fuel at 2.33 per litre: 450 × 8 ÷ 100 = 36 litres; 36 × 2.33 = 83.88. Split between 3 passengers, each pays 27.96. A car rated at 12 km/L on a 120 km road, there and back, needs 240 ÷ 12 = 20 litres. In miles: a 300-mile road trip at 30 mpg uses 10 gallons; at $3.50 a gallon the gas costs $35, or $70 there and back — $17.50 each for four friends.
Planning a road trip budget
- Get the driving distance from your maps app (one way).
- Use your car’s real-world mpg or L/100 km — the trip computer or a full-tank test is better than the sticker.
- Enter today’s average price where you will fill up; prices can vary a lot between regions and along highways.
- Tick round trip if you are coming back, and add passengers to split the cost.
- Add 10–15% as a buffer for detours, traffic and air conditioning.
Converting between the two units
L/100 km = 100 ÷ (km/L)So 12.5 km/L equals 8 L/100 km, and 10 km/L equals 10 L/100 km. US mpg converts with km/L = mpg × 0.425 and L/100 km = 235.21 ÷ mpg; the fuel economy calculator converts every unit and measures your real mpg.
Getting a realistic number
- Use your car’s real consumption from the trip computer or a full-tank test; official figures are usually optimistic.
- Air conditioning, heavy loads, high speeds and city traffic can raise consumption by 10–30%.
- Fuel prices change — in many Gulf countries and in Egypt they are reviewed monthly or quarterly — so enter the current price at the pump.
To compare the trip with other costs, use the percentage calculator, or, if you are financing a car, the loan calculator.