There is one number in a transport arrangement that nobody can look up: how many trucks you promise to pay for every week whether or not you use them.
Get it too high and you buy standing capacity that sits in your yard. Get it too low and you spend the year buying days at whatever the market charges that morning. Most operations settle it by taking a busy week, rounding up, and never revisiting it.
The number is findable. It falls out of two pieces of arithmetic, and they are different pieces: one prices the truck, and the other counts the days it can actually work. Doing only the first is the usual mistake.
Weekly demand is a shape, not a number
Before any of this, you need the shape. Take your last eight to twelve weeks of despatches, one row per operating day, and write down the number of vehicle-days each day genuinely needed. Not the number you booked, and not the tonnage. The vehicle-day is the unit that gets bought and sold, and it is the one your carrier is pricing.
You now have a distribution rather than an average. Say sixty operating days came out like this.
| Vehicle-days needed | Days at that level |
|---|---|
| 4 | 6 |
| 5 | 12 |
| 6 | 18 |
| 7 | 13 |
| 8 | 7 |
| 9 | 3 |
| 10 | 1 |
That is 376 vehicle-days across sixty days, an average of 6.27 and a peak of 10. Both numbers are true and neither is the answer.
The one thing this table tells you immediately is what sizing to the peak costs. Commit ten trucks and they are busy 376 days out of 600, which is 62.7 per cent. The other 224 days are paid for and idle, and they are not paid for by the peak, which happened once.
Committing between the average and a little above it
The standard rule of thumb, and it is a good one, is to resource between average demand and average plus 10 to 20 per cent, then buy the rest on the day. On the figures above that says commit seven, because 6.27 plus 15 per cent is 7.21.
Run the utilisation at each level and the shape of the trade appears.
| Committed trucks | Vehicle-days used | Committed vehicle-days | Utilisation | Days needing top-up |
|---|---|---|---|---|
| 5 | 294 | 300 | 98.0% | 42 |
| 6 | 336 | 360 | 93.3% | 24 |
| 7 | 360 | 420 | 85.7% | 11 |
| 8 | 371 | 480 | 77.3% | 4 |
| 9 | 375 | 540 | 69.4% | 1 |
| 10 | 376 | 600 | 62.7% | 0 |
Utilisation falls away fast above the average, which is what the rule of thumb is protecting you from. But utilisation is not money. To turn this into a decision you have to price the truck you are thinking about adding.
What each extra committed truck actually removes
Every committed truck costs the same thing: sixty vehicle-days over this window, paid whether used or not. What differs is how much shortfall it removes.
| The truck you are adding | Shortfall vehicle-days removed | Top-up price it must beat |
|---|---|---|
| 5th | 54 | 1.11 Γ committed |
| 6th | 42 | 1.43 Γ committed |
| 7th | 24 | 2.50 Γ committed |
| 8th | 11 | 5.45 Γ committed |
| 9th | 4 | 15.0 Γ committed |
| 10th | 1 | 60.0 Γ committed |
Read the last column. The fifth truck pays for itself if a day bought on the market costs more than 1.11 times a committed day, which it always does. The sixth needs a 43 per cent premium, which is plausible. The seventh needs the market to charge two and a half times your contract rate, which it almost never does. The eighth needs five and a half times, and after that the numbers stop being about transport.
That is the uncomfortable result, and it is arithmetic rather than opinion: on price alone, the commitment usually stops at or just below the average, not above it. The rule of thumb sits a little higher than the money does, because the rule of thumb is quietly buying something else.
What it is buying is availability, and availability has to be argued for separately. If the extra truck is there so that a day never fails, then price it against the cost of the failure, not against the cost of a spot day. Those are different sums and mixing them is how a fleet grows without anybody deciding to grow it.
One check before any of this means anything. This whole calculation assumes a committed vehicle-day is paid for whether you use it or not, and a top-up day is paid for only when it runs. If your committed arrangement bills you only for the days you use, you have not committed to anything. You have a spot arrangement with a reassuring name, and the carrier is holding the risk you think you are paying to transfer.
A committed truck is not an available truck
The second piece of arithmetic has nothing to do with demand. It counts the days a truck and a named driver can lawfully deliver.
Start with the calendar. An employee is owed at least one weekly holiday, which is 52 days. At least thirteen traditional holidays a year must be announced in advance, and where one of them falls on the weekly holiday the employee takes the substitute on the next working day, so the thirteen cannot be absorbed by the rest days. After a full year of service, at least six working days of annual leave are owed on top.
That leaves 294 days out of the 313 an operation working six days a week is open. One driver covers 93.9 per cent of your operating year, and 19 days of it belongs to somebody else, before a single day of sickness, training, inspection or workshop time.
Turned around: keeping one truck running on all 313 days needs 1.065 drivers. Ten committed trucks need eleven drivers to be a real ten. If the arrangement you are buying has ten trucks and ten drivers, you have bought about 190 truck-days a year of quiet unavailability, and it will surface as a refusal on a day you did not choose.
There is a lever here that most people never use. For transport work specifically, the employer and the employee may agree in advance to accumulate weekly rest days and take them later, within four consecutive weeks. That is the legal mechanism for moving a rest day out of your month-end and into the quiet week that follows it. It has to be agreed beforehand, it does not stretch past four weeks, and it does not touch the thirteen traditional holidays. Within those limits it is free capacity that already exists inside the arrangement.
The market you top up from is not the market you can see
The whole plan above rests on being able to buy a day when you need one. How true that is depends on where you are, and it is much less true than the traffic suggests.
The Department of Land Transport counted 38,071 non-fixed-route goods licences in force at the end of February 2026, against 312,558 private goods licences. Those two numbers describe different things. A private licence covers moving goods for one's own trade or business. It does not permit carrying for hire, and the holder cannot sell you a truck-day, whatever is parked outside. Most of the trucks you see are in the second number and are not available to you at any price.
Within the 38,071 that can carry for you, the size distribution matters more than the total. The Department's freight bureau groups non-fixed-route truck operators by fleet size, and of 40,570 operators counted, 33,502 run ten vehicles or fewer. That is 82.6 per cent of the market. Only 1,842, or 4.5 per cent, run more than fifty.
Now look at your own province, because that is the market you can actually reach on a Tuesday morning.
- Across the 76 provinces and Bangkok, 16 have fewer than five non-fixed-route operators running more than thirty vehicles.
- Mae Hong Son has 56 non-fixed-route operators and not one of them is above thirty vehicles.
- Bangkok, Chonburi and Samut Prakan between them hold 741 of the 1,842 largest operators, which is 40.2 per cent.
- Ubon Ratchathani has 2,144 operators, which sounds deep, until you see that 2,029 of them run ten trucks or fewer and only 14 run more than fifty.
Two things follow. First, in most of the country the top-up market is wide and shallow: many operators, almost none of them able to absorb a three-truck spike on short notice. Your peak is not covered by one phone call, it is covered by four. Second, depth is local. A carrier is licensed for a stated locality, and using its vehicles to carry outside the authorised locality without written permission from the registrar is an offence penalised by the number of vehicles involved, at up to 5,000 baht per vehicle per day until it is corrected. A large operator two provinces away is not automatically a supplier.
If your province is in the shallow half of that table, the availability argument for one more committed truck gets stronger, and the price argument does not have to win on its own.
Why your carrier cannot simply add two trucks for you
When you ask for dedicated capacity to go from six to eight and the answer is "give us a few weeks", that is usually not a stall.
The number of vehicles a non-fixed-route operator must use in its business is not a commercial choice. It is a condition written into the operating licence by the registrar with the approval of the Board, alongside the vehicle types and marks, the loading criteria, the number of crew, the locality served, the service standards, the rates, the stopping places and the yard where vehicles are kept and maintained. Failing any of those conditions carries a fine of up to 50,000 baht.
Worth noting is what this does not say. A fixed-route operator that runs short of the vehicle number in its licence is fined per vehicle short, per day, until it is put right. A non-fixed-route operator faces the flat penalty instead. So the licence fixes the shape of your carrier's fleet, but it is not the thing that forces trucks to turn up at your gate on a Monday. That job belongs to your contract, and if your contract does not name a number of vehicle-days a week, nothing else will.
The practical consequence is a lead time. Changing committed capacity touches a licence condition, a yard, and a crew count. Ask for it a quarter ahead, not a week ahead, and expect the carrier to want a term long enough to justify the change. That is the same reason a carrier prices short-notice work the way it does, and the same reason a job that arrives without warning gets declined rather than discounted.
Setting the number, and what to write down
- Build the distribution. Eight to twelve weeks of operating days, one number each: vehicle-days genuinely required. Exclude nothing for being unusual, but mark the days you know were caused by your own order rules rather than by customers.
- Compute average and peak, then the shortfall table. For each candidate level, the vehicle-days above it. The marginal removals fall away fast and the table tells you where.
- Get a real top-up rate before you decide, not after. Ask two or three carriers what a day costs at three days' notice and at one. The ratio between that and your committed rate is the only number that settles the level.
- Commit where the ratio still works, which will usually be at or a little below the average, and buy the rest on the day.
- Add availability on top as a separate decision, with the reason written down. One extra truck bought because a stockout costs more than a truck is a defensible decision. One bought because the peak week frightened somebody is not.
- Check the driver count against the calendar, not against the truck count. 294 days per driver, 1.065 drivers per truck for a six-day operation.
- Check the depth of your province before you rely on topping up. Count the operators near you that are large enough to lend you a truck at short notice. If the answer is two, plan differently.
And write these five things into the arrangement, because none of them survive as an understanding.
- The commitment in vehicle-days a week, not in trucks, with what happens when you use fewer.
- The top-up rate and the notice it applies to, agreed now and not on the morning you need it. The ladder of what each step of notice buys is the same ladder your carrier is pricing from.
- The named peak weeks you already know about, so capacity is planned rather than found.
- The rest-day accumulation agreement, in advance and within four weeks, if your peak is predictable and monthly.
- A review date, with the distribution rebuilt from the following quarter's data.
A committed number set this way will be wrong within a year, because your demand shape moves. That is fine and it is the reason for the review date. What is not fine is a number nobody can explain, protecting against a peak that happened once, on a lane whose route pattern was never settled in the first place.