Your truck's real cost per kilometre. Worked out line by line.

Your cost per kilometre is the one number every quote should start from. If you know it, you know the lowest rate you can take on a lane without losing money. If you guess it, the diesel price, a toll plaza or an empty return will decide your margin for you.

This guide splits the cost into the parts that move with distance and the parts that do not, then puts them together.

1. Variable costs: the ones that grow with every kilometre

Diesel

Diesel is the biggest variable cost for most long-distance trucks. The formula is simple: litres per kilometre times the price per litre.

The official wholesale price changes on the first Wednesday of each month. On 2 September 2026 the Department of Mineral and Petroleum Resources raised 50 ppm diesel by 314,90 cents a litre (DMPR), which put inland 50 ppm diesel at R 30,05 a litre, with the coast a little lower (The Citizen). Use the price for your own region, or what you actually pay at your depot.

For consumption, use your own fuel records or your tracking system, per truck and per type of load. A loaded interlink uses more than the same truck running empty. In the example below we use 46 litres per 100 km for a loaded interlink, which is an assumption for illustration, not a benchmark. (The quote on our product pages is a different truck: a 28 t superlink on the same Johannesburg to Durban lane, at 37,3 litres per 100 km.)

Work this out per truck, not as a fleet average. Say three interlinks each run 12 000 km a month at 44, 46 and 52 litres per 100 km (example inputs). The fleet average is 47,3 litres per 100 km, or R 14,22 per km. But the thirsty truck really costs R 15,63 per km in diesel and the best one R 13,22.

Quote that truck on the average and you lose about R 800 a trip before you start. Quote the efficient truck on the average and you price yourself about R 1,00 per km above what you need to.

Road freight is not one of the activities that qualify for the diesel refund, which is limited to farming, forestry, mining, some marine uses, rail freight and large power plants (SARS). So price the full pump price.

Tolls

Tolls depend on the lane, so work them out per route rather than as an average. SANRAL publishes its tariffs by vehicle class; class 4 covers vehicles with five or more axles, such as an interlink. From 1 March 2026 a class 4 truck pays R 1 274 at the five N3 mainline plazas between Johannesburg and Durban: De Hoek, Wilge, Tugela, Mooi and Mariannhill (SANRAL).

SANRAL tariffs include VAT. If you are a VAT vendor you claim that VAT back, so the cost to you is R 1 107,83 excl. VAT. Over the 570 km from City Deep to Prospecton that adds R 1,94 per km on that lane.

Tyres and maintenance

Take these from your own workshop and tyre records over at least a year, divided by the kilometres the truck ran. The Road Freight Association publishes a Vehicle Cost Schedule you can use as a cross-check (RFA). In our example the inputs are R 2,40 per km for tyres and R 1,80 per km for maintenance.

2. Fixed costs: the ones you pay even when the truck stands

Finance, the driver (at or above the bargaining council minimums, NBCRFLI), insurance, licences, tracking and a share of your overheads are paid every month whether the truck moves or not. Fixed costs in our example come to R 81 600 a month (the line-by-line budget is in the true cost of running a truck).

At 12 000 km a month, that is R 81 600 ÷ 12 000 = R 6,80 per km.

Kilometres decide the fixed cost per km

The R 81 600 does not change when the truck runs less, so the cost per kilometre does. Here is the same truck at different monthly distances, with the variable costs above (diesel R 13,82, tyres R 2,40, maintenance R 1,80: R 18,02 per km).

A truck that loses a week to a breakdown or waits for loads can drop from 12 000 to 8 000 km in a month, and its cost per kilometre rises by R 3,40. Use the kilometres the truck really runs over the last few months, not the kilometres you hope for.

3. Put it together

4. From cost per km to a minimum rate per loaded km

The figures above are per kilometre driven. Customers pay for loaded kilometres. If one kilometre in five is empty, your cost per paid kilometre is R 24,82 ÷ 0,8 = R 31,03 before tolls. This is the number that decides whether a lane works, and it is the one most often left out.

On a tolled lane, add the tolls first, then spread the empty running over the loaded kilometres:

This assumes the empty kilometres run on the same tolled road. If the truck comes back on a different route, work out that leg's cost separately. The result is a floor, not a price: a load below it loses money on every kilometre. How much margin to add on top, and when to walk away from a lane, is a pricing decision, covered in how to price loads profitably.

5. Keep it current

• Update the diesel price on the first Wednesday of every month.
• Update tolls every March, when SANRAL's new tariffs take effect.
• Recalculate fixed costs when a finance deal, insurance premium or wage agreement changes.
• Work out consumption per truck, not per fleet: one thirsty truck hides in an average.

This post turns costs into a rate. For the full monthly and yearly budget of owning a truck, see the true cost of running a truck. To put the figure to work, follow the worked quote, or see how TruckWys prices a load from the same inputs.