Fuel Cost Calculator
Work out the fuel cost of any trip.
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Before a long drive, the question is simple: how much will the fuel cost? Enter the distance, your car's fuel efficiency, and the current price at the pump, and this calculator estimates the fuel needed and the total cost — in km or miles.
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How to Calculate Trip Fuel Cost — The Quick Answer
Work out how much fuel the trip needs, then multiply by the price. Divide the distance by your efficiency (in matching units) to get the fuel, then multiply by the cost per unit of fuel.
Shortcut
fuel needed = distance ÷ efficiency cost = fuel needed × price per unit
A 300 km trip at $1.60 per litre
| Efficiency | Fuel used | Cost |
|---|---|---|
| 5 L/100km | 15.0 L | $24.00 |
| 7.5 L/100km | 22.5 L | $36.00 |
| 10 L/100km | 30.0 L | $48.00 |
Fuel efficiency is the key variable — it changes the cost far more than small differences in the pump price. Using your real-world average (not the brochure figure) gives a more accurate estimate.
How It Works
The Method
Fuel used, then cost
Formula
fuel (L) = (distance ÷ 100) × L/100km cost = fuel × price per litre
Variables
Fuel economy
How far your car goes per unit of fuel. L/100km (lower is better) and MPG (higher is better) measure the same thing in opposite directions. This calculator converts your chosen unit to litres per km internally.
Cost per unit of fuel
Multiply the fuel the trip needs by the price per litre (or per gallon). If your price is per gallon, it's converted to per-litre first, since the fuel is calculated in litres.
Note: This estimates fuel for the driving only. It ignores things like idling in traffic, air-conditioning, load, and terrain, all of which reduce real-world efficiency below the figure you enter.
Last updated: October 6, 2026
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Frequently Asked Questions
How do I calculate the fuel cost of a trip?
Work out how much fuel the trip uses, then multiply by the price per litre. For a 300 km trip in a car doing 7.5 L/100km with fuel at $1.60/L: the trip uses 22.5 litres, costing $36.00. Enter your own numbers above for an instant estimate.
What fuel efficiency should I use?
Use your car's real-world average, not the manufacturer's optimistic figure. A tank-to-tank calculation (miles driven between fill-ups divided by fuel added) gives your true consumption. Real efficiency also drops in city driving, in cold weather, and with a full load.
How does MPG compare to L/100km?
They're inverse measures. L/100km states the litres used per 100 km (lower is better); MPG states the miles driven per gallon (higher is better). This calculator converts between them automatically, so you can enter whichever your car or region uses.
Is this cost per person or for the whole car?
For the whole car — the total fuel cost of the trip. To split it between passengers, divide the total by the number of people. The cost-per-km and cost-per-mile figures are also shown if you want to work it out another way.