Guides › Diesel cost per trip
How to calculate diesel cost for a truck trip, including the empty return
Diesel is the biggest cost of almost every trip, and the easiest one to underestimate. This guide shows a simple, accurate way to calculate it, and the two shortcuts that quietly cost thousands of rupees per trip.
In short
- Diesel = kilometres ÷ mileage × price per litre, worked out for the whole cycle.
- A truck gives lower mileage loaded than empty, so calculate the two legs separately if you can.
- Use the mileage your truck actually gives, not the brochure figure.
- In the example, diesel is about 64% of the trip's variable cost, so every ₹5 change in diesel price moves the trip by ₹1,250.
The basic formula
Diesel cost = (km ÷ km per litre) × ₹ per litre
Simple enough. The mistakes come from which kilometres you count and which mileage you use.
Step 1: Count every kilometre of the cycle
Our example trip is 750 km loaded. After unloading, the truck runs 250 km empty to its next loading point. Both legs burn diesel, and both are paid for by this trip. The cycle is 1,000 km.
If the truck sometimes drives to a loading point first (repositioning), add that too.
Step 2: Use loaded and empty mileage separately
A loaded truck uses more fuel per kilometre than an empty one. If you know both figures for your truck, calculate each leg on its own:
| Loaded leg: 750 km ÷ 3.75 km/l | 200 litres |
| Empty leg: 250 km ÷ 5 km/l | 50 litres |
| Total diesel | 250 litres |
| Price per litre (example) | × ₹90 |
| Diesel cost for the trip | ₹22,500 |
The 250 litres over 1,000 km works out to an average of 4 km/l. That's the figure our other guides use, so the numbers line up.
Per kilometre that's ₹22.50 per km driven, but ₹30 per loaded km, because the 750 loaded kilometres have to pay for the empty ones too.
Two shortcuts that understate diesel
| One-way only: 750 km ÷ 4 km/l × ₹90 | ₹16,875 |
| Brochure mileage: 1,000 km ÷ 5 km/l × ₹90 | ₹18,000 |
| Whole cycle, real mileage | ₹22,500 |
Counting only the loaded leg misses ₹5,625 per trip. Using a brochure figure misses ₹4,500. Over 8 trips a month, either mistake hides ₹36,000–₹45,000 of diesel that still has to be paid.
Watch out: brochure mileage is measured in test conditions. Real mileage depends on load, road, traffic, idling and the driver. Use figures from your own fill-ups, and update them when you change routes or drivers.
How sensitive is the trip to diesel?
In the example, diesel is ₹22,500 of the trip's ₹35,000 variable cost, about 64%. Small changes move the result a lot:
| Change | Effect on one trip | Over 8 trips |
|---|---|---|
| Diesel price up ₹5/litre (250 litres) | + ₹1,250 | + ₹10,000 |
| Loaded mileage 3.5 instead of 3.75 km/l | + 14.3 litres ≈ ₹1,286 | ≈ + ₹10,300 |
Put both together and a truck can lose ₹20,000 a month of profit with nothing about the work changing. If your freight contract fixes the rate for months, check whether it has a diesel price adjustment clause.
How to measure your real mileage
- Fill the tank to full and note the odometer reading.
- Run a normal trip.
- Fill to full again, at the same kind of pump if possible, and note the litres added.
- Kilometres driven ÷ litres added = your mileage for that trip.
- Repeat on several trips. Keep loaded and empty runs separate if your trip sheets allow it.
Run it with your own numbers
FleetProfit's trip calculator works out diesel for loaded, empty and repositioning kilometres, flags brochure mileage, and shows what the diesel bill does to the trip's profit.
Open the trip calculatorCommon questions
How do I measure my truck's real mileage?
Fill the tank to full and note the odometer. Run a normal trip, then fill to full again at the same kind of pump. Kilometres driven divided by litres added is your mileage. Repeat over several trips, and keep loaded and empty runs separate if you can.
Should I use the diesel price at the start or the average on the route?
Use what you actually expect to pay. Prices differ between states, so if you fill up in several places, use a weighted average based on how many litres you buy where.
Does waiting with the engine running cost much?
It can. Idling at loading points, at checkposts or to keep the cabin cool uses fuel without moving the truck. Measure it on your own routes. If it's significant, add it as a separate line rather than hiding it in the mileage figure.