The per-kilometer cost of a truck corresponds to the actual price represented by each kilometer traveled, incorporating all the expenses related to the vehicle. It is not a standard rate: two identical trucks, operated differently, show distinct per-kilometer costs. The accuracy of this estimate directly affects the profitability of a transport activity.
The CNR’s trinomial formula: an approach that goes beyond the simple euro per kilometer
Most simplified calculations divide total expenses by the number of kilometers traveled. The result provides an average but masks costly operational realities.
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The National Road Committee (CNR) formalizes a more nuanced approach with its trinomial formula. This breaks down the cost into three distinct units: kilometers driven, driver service hours, and days of vehicle use. The benefit of this breakdown is to capture costs that are invisible in a classic calculation.
A truck immobilized at a loading dock for several hours generates an hourly cost (driver salary, vehicle depreciation, insurance) that does not appear in a simple euro/kilometer ratio. Similarly, a day of immobilization for maintenance remains a day of fixed costs without generating kilometers. The calculation of a truck’s per-kilometer cost gains reliability when it incorporates these three dimensions rather than a single kilometer divisor.
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Empty kilometers: the item that many underestimate in the actual cost
A loaded outbound trip followed by an empty return doubles the actual distance without doubling the revenue. Empty kilometers are one of the most frequently underestimated items in the estimation of per-kilometer costs.
The trap is mechanical: if a carrier travels 500 km loaded and 500 km empty, their actual cost per billed kilometer is calculated on 1,000 km of expenses but only 500 km of revenue. The unit cost charged to the client must therefore absorb both trips.
In unbalanced flows (delivery to a rural area without return freight, for example), this ratio can significantly degrade the margin. A reliable calculation requires systematically integrating the loaded return rate into the formula. The lower this rate, the further the actual per-kilometer cost diverges from the apparent per-kilometer cost.
Fixed and variable costs: distinguishing to better manage the cost per kilometer
The distinction between fixed and variable costs is not just an accounting exercise. It determines how the per-kilometer cost evolves based on the level of activity.
Fixed costs that weigh even when stationary
- The depreciation or rental of the vehicle (credit, long-term lease) runs independently of the mileage covered. A truck that drives little costs more per kilometer than a truck that drives a lot, with identical fixed costs.
- The insurance for the heavy vehicle represents an unavoidable annual amount, regardless of the number of trips made.
- Taxes and fees related to the vehicle (axle tax, certificates) add up without a direct link to the distance traveled.
Variable costs related to each kilometer
- Fuel is the heaviest variable item. Its share in the cost of a heavy vehicle is around a quarter of total expenses, according to industry data. Accurate tracking of average consumption (liters per 100 km) is the basis for any serious estimate.
- Tires wear out in proportion to distance. Their cost per kilometer varies depending on the type of road, the load carried, and the inflation pressure.
- Routine maintenance (oil changes, filters, brakes) and unforeseen repairs increase with mileage. A rigorous maintenance log allows for anticipating these expenses rather than suffering them.
The basic formula remains: (annual fixed costs + annual variable costs) / kilometers traveled in the year = per-kilometer cost. The accuracy depends entirely on the comprehensiveness of the items included in the numerator.
Non-driving time and driver costs: what the odometer does not measure
The driver’s salary represents a major item, but its cost is not limited to driving hours. Waiting times for loading, handling operations, administrative formalities at borders or on-site constitute non-driving billable hours of service.
A carrier who only charges based on kilometers traveled undervalues missions with dock constraints, imposed time slots, or manual unloading. These non-productive hours in terms of distance traveled remain productive in terms of salary costs and social charges.
Integrating the hourly cost of the driver (gross salary loaded divided by the number of hours worked) into the estimate allows distinguishing a 300 km trip completed in four hours from an identical trip that takes seven due to waiting. The apparent per-kilometer cost is the same, but the actual cost is not at all.
Frequency of recalculating the per-kilometer cost: an indicator that ages quickly
The price of diesel fluctuates, insurance contracts are renegotiated, tire prices change, and annual mileage varies from one fiscal year to another. A per-kilometer cost calculated six months ago may already be outdated.
The best practice is to recalculate the per-kilometer cost at least quarterly, updating the most volatile items (fuel, wear parts). Carriers who monitor this indicator monthly detect deviations more quickly and adjust their rates before margins erode.
The per-kilometer cost of a truck is not a fixed number but a management indicator. Its reliability rests on three points: integrating empty kilometers into the calculation, not forgetting non-driving hours, and regularly updating the data. A difference of a few cents per kilometer, multiplied by tens of thousands of annual kilometers, is enough to turn a profitable exercise into a loss-making one.