Fuel Cost per Trip Calculator

Fuel cost per trip calculator for road trips, commutes, and errands

This calculator estimates how much fuel a specific trip will use and what that fuel will cost, based on three things: your trip distance, your vehicle fuel efficiency, and the fuel price per litre. It is designed for normal, real-world use. You can get a quick answer in seconds, or you can refine the estimate if your trip includes detours, a return journey, or a shared cost between passengers.

To use it, start with the trip distance and pick the unit that matches what you see on your map app or odometer: kilometres or miles. Next, enter your vehicle’s fuel efficiency. If you know your typical consumption as L/100km, that is usually the easiest. If your car reports km/L or mpg, you can choose that unit and enter the value as-is. Finally, enter the current fuel price per litre. The calculator converts everything into a consistent format behind the scenes and then estimates fuel used and cost.

The results include more than a single total. You will see estimated litres used, the total trip fuel cost, the cost per kilometre, and (if you enter more than one person) an estimated cost per person. The per-kilometre number is useful for comparing two route options, comparing your vehicle to another one, or deciding whether a short trip is worth it when fuel prices jump.

Assumptions and how to use this calculator

• Fuel efficiency is treated as constant for the trip. Real driving varies with speed, traffic, load, tyres, and air conditioning.
• Fuel price is assumed to be per litre and stable for the whole trip. If prices vary by region, use an average.
• If you choose miles, the calculator converts miles to kilometres before estimating fuel used.
• The “Extra distance” percentage is a simple buffer for detours, wrong turns, or route changes. It increases total distance before the fuel estimate.
• Cost per person is a simple split of fuel cost only. It does not include tolls, parking, maintenance, or depreciation.

Common questions

What fuel efficiency unit should I use?

Use the one you trust and can enter confidently. Many drivers in metric regions know L/100km from the car display or trip computer. If you have km/L or mpg from your vehicle or a spec sheet, choose that unit instead. The calculator converts it into an equivalent L/100km value internally so the final litres-used estimate stays consistent.

What if I do not know my exact fuel efficiency?

Use a realistic typical value. If you have a mixed driving pattern, pick something close to what you see over a few weeks rather than a best-case highway figure. If you want a safer budget estimate, use a slightly worse efficiency than normal. That gives you a buffer so the fuel cost estimate is less likely to be too low.

Should I include a detour percentage?

If your trip is simple and you have a reliable route distance, you can leave it blank. If you expect traffic diversions, multiple stops, or driving around at the destination, adding 5% to 10% often produces a more realistic total. For unfamiliar routes or busy cities, a higher buffer can be sensible.

Does “Round trip” double everything?

It doubles the distance used for the calculation, which typically doubles fuel used and total cost. It does not change efficiency or fuel price. If your return drive is likely to be very different (for example, towing on the way back or heavy traffic at a different time), a single estimate can still be useful, but it will not capture those differences perfectly.

Why is cost per kilometre useful?

Cost per kilometre helps you compare options. For example, if one route is 20 km longer but avoids steep hills or stop-start traffic, the total fuel cost difference might be smaller than you expect. It also helps you sanity-check fuel spending across trips, since it turns fuel price and efficiency into a single number you can compare over time.