Fuel is often one of the largest variable transport expenses, so a relatively small change in consumption or price can materially change a trip result. A reliable calculation starts by separating two questions: how many litres the truck will use and how much those litres will cost.
1. Calculate litres first
The main inputs are trip distance and realistic average consumption in l/100 km. Use your own vehicle history under similar conditions instead of a catalogue figure. Winter, payload, terrain, speed, idling and driving style can all move the result.
2. Then choose a realistic fuel price
If the route crosses several countries, one national average may not match your actual purchasing pattern. For planning, you can use an automatically updated reference price or enter your own contract or station price manually.
Always note the price date and currency. When comparing a PLN price in Poland with EUR costs, the exchange rate also affects the final result.
3. Fuel cost and diesel surcharge are different
Trip fuel cost estimates what you expect to pay for fuel. A diesel surcharge is a contractual mechanism that passes part of a fuel-price change into the selling price.
A common model contains:
- a base fuel price;
- a current or contract-defined comparison price;
- a fuel share or another agreed factor;
- a rule describing when and how the price is adjusted.
4. Use the same method in both directions
When fuel rises, a surcharge may increase. When it falls, the adjustment may decrease under the same contract logic. Consistency matters: use the same source, reference date and formula so both parties can reproduce the calculation.
5. Carry the result into profitability
Fuel should not remain an isolated calculation. Feed the updated fuel cost into cost per kilometre
Calculate the adjustment from your contract data
Updated: 2026-08-31