A returnable pallet, crate or bin is sold as a saving. You pay more once and stop buying cardboard or cheap pallets every trip. That is true only if the thing comes back, and comes back often enough. The price is paid on day one. The saving arrives one lap at a time.
Most of the money in a returnable system is not in the containers. It is in how many of them the loop needs to hold, how many leak out of it, and what it costs to carry the empties home. All three are set by habits at the customer's dock and in your own yard, and none of them shows up on the purchase order.
This article covers the equipment loop: pallets, crates, bins, racks and bulk bags that are meant to come back. Goods a customer refused at the gate are a different problem, covered in what a failed delivery really costs.
What a leaking loop looks like
The Ministry of Industry's logistics office documented a case among Thai bagged rice packers. Two companies moved their 5 kg retail bags in large woven jumbo bags that were supposed to be returned and reused.
The loop had three faults.
- Two bag sizes were in use, 90 x 90 x 80 cm and 90 x 90 x 100 cm.
- Each customer took a different count per bag, 60, 80 or 120 retail bags. So counting, holding spares and negotiating the bag price were all harder than they needed to be.
- More than half the bags were lost, not returned, damaged or mixed up with someone else's. Buying replacements cost at least 50,000 baht a day, before the cost of sorting and reconditioning the ones that did come back.
The answer proposed was not a better bag. It was one standard bag, one fill limit of 600 kg and one set of rules for reuse. The reasoning was that one kind of bag, filled one way, is something a dock can count.
That is the pattern to take away. A loop leaks where nobody can count it, and nobody can count it when every customer does something slightly different.
Size the pool from the loop, not from the order
The first mistake is buying containers to match a day's shipments. A container is not used once a day. It is tied up for the whole time it takes to go round.
Research on returnable packaging in Thai automotive parts supply gives the working rule. The number you need is the most you use in one period, multiplied by the number of periods the container spends in each place it stops. Round up. Then add a safety stock for damage and for swings in orders.
In plain terms: pool = daily issue Γ days round the loop.
Here is an illustration, with made-up figures. A distributor sends out 300 plastic crates a day, six days a week. Count every stop in days:
| Where the crate is | Days |
|---|---|
| Filled and waiting to load | 1 |
| On the truck to the customer | 1 |
| At the customer until the next visit collects it | 4 |
| On the truck back | 1 |
| Sorted, cleaned, back on the shelf | 1 |
| Total loop | 8 |
The pool is 300 Γ 8 = 2,400 crates before any safety stock.
Now let the customer hold the empties for nine days instead of four, because deliveries there drop to once a week or nobody asks for them. The loop becomes 13 days and the pool 3,900 crates. Every extra day a customer keeps your empties adds one full day of issue to the pool, here 300 crates, bought and sitting still.
This is why the customer's holding time is the number to manage, and why it belongs in the agreement with the customer rather than in a warehouse procedure.
The loss rate a returnable can survive
A returnable only pays back after enough laps. How many it gets depends far more on loss than on wear.
The same Thai automotive research puts returnable plastic containers at about 5 to 15 times the price of a one-way carton. Plastic lasts 6 to 8 years, and metal more than 10. On the eight-day loop above, a crate can go round about 39 times a year, so a six-year life allows roughly 234 laps. Wear is rarely what ends it.
Loss is. If a fraction p of containers goes missing on each lap, the average container makes about 1 Γ· p laps before it is gone. At 2% a lap that is 50 laps, or about 15 months on this loop, against a working life of six years.
So the test is simple. Call the returnable's price k times the one-way item, and call the cost of bringing one empty back and cleaning it r, as a share of the one-way price. Each lap the returnable saves (1 β r). It pays for itself after k Γ· (1 β r) laps, and the loss rate must stay below (1 β r) Γ· k.
| Returnable costs | Return and cleaning per lap | Laps to break even | Loss per lap must stay under |
|---|---|---|---|
| 5 Γ one-way | 20% of one-way | 6.25 | 16% |
| 10 Γ one-way | 20% of one-way | 12.5 | 8% |
| 15 Γ one-way | 20% of one-way | 18.75 | 5.3% |
Put the rice case through it. With more than half the bags not coming back, the average bag made fewer than two laps. At that loss rate, a returnable at 20% return cost only beats a one-way item if it costs less than 1.6 times as much. Almost nothing built to be reused is that cheap. At a loss rate like that the returnable system is not saving money. It is buying one-way packaging at a returnable price.
Measure your own loss rate before you buy the next batch, not after.
Count the return leg on every lap
The second common mistake is paying for the return transport once instead of every time.
A motorcycle maker in Amata Nakorn replaced one-way steel shipping frames with returnable ones. The one-way frame cost 3,308 baht. The returnable one cost 6,000. Bringing the empties back cost 65,969.65 baht for a 40-foot container holding 126 frames, which is 523.57 baht per frame for each lap.
The study added one return share to the frame price, got 6,523.57 baht, divided by 3,308 and concluded the frame paid for itself in about two laps.
The return is paid on every lap, though, not once. Set it up that way and the frame saves 3,308 β 523.57 = 2,784.43 baht a lap. It takes 6,000 Γ· 2,784.43 = 2.15 laps to recover the price, so it pays for itself on the third lap. Take off the 510 baht scrap value the one-way frame would have fetched and it is 2.64 laps: still the third.
With six laps a year on a 60-day loop, the investment still pays back comfortably. The conclusion survived, but the calculation behind it did not, and on a lane with thinner margins that difference decides whether the change is worth making at all. That was an export lane. On a domestic lane the return share is a slice of a truck rather than a container, and the rule is the same.
Carrying empties home is transport, and it has to be planned
Empties take space and earn nothing. Four things decide what they cost to bring back.
- Whether they fold or nest. The Thai automotive research names stackability when full and nestability when empty as design requirements for exactly this reason. A crate that nests takes a fraction of its full space on the way back. A rigid box or a fixed steel rack takes the same space both ways.
- Whether they ride on a vehicle already going that way. Collecting empties on the delivery vehicle's return leg is usually the cheapest option, and the ground rules for using that leg are in backhaul and return loads.
- Whether collecting them breaks the delivery route. Collecting returns on outbound delivery vehicles is hard precisely because it can push back the times already promised to other customers. An unplanned stop to pick up forty crates at drop two makes drops three to six late.
- Whether the count is the same in both directions. The automotive milk run works because the vehicle leaves as many empties as the filled containers it collects. The swap is the control. When it does not happen at the dock, it rarely happens later.
Plan the collection as its own task with its own time, even if it rides on the same truck. A pickup of empties that goes into the plan costs a few minutes. One that is left to the driver's goodwill costs a late drop, or a pile of empties that stays at the customer until the pool runs short.
Who runs the loop decides how well it is controlled
The Thai automotive research found two ways of running a loop.
In one, the customer at the centre owns the containers, plans how many are needed and controls the stock. Visibility is good and stock stays low, because one party sees the whole production plan.
In the other, each supplier owns and manages its own containers. More than 80% of Thai automotive parts supply works this way. It is more flexible, because a supplier can borrow from its own stock when a container is damaged. But stock runs higher and is harder to control, because the supplier plans against a customer demand it sees less clearly, and without good communication with the customer the containers pile up in the process.
Most operations outside the automotive trade look like the second model, often without deciding to. The same research describes Thai parts makers with no systematic control at all: they cannot see where their containers are, and when they run short they buy more without checking how many are already in circulation. The shortage is real. The containers still exist. They are just sitting at the customers.
The fix the research proposes is ordinary inventory discipline applied to something nobody thinks of as inventory:
- Give each container type a part number, and list it on the bill of materials for the product it carries.
- Plan it like a material, from the same production plan that drives the product.
- Mark it so it can be sorted. Automotive suppliers colour-code their containers so returns can be split by owner at the customer's dock. A barcode, QR code or RFID tag does the same job with a record attached.
What to do this month
- Draw your loop. List every place a container stops and how many days it stays in each. The customer's holding time is usually the longest and the least known.
- Work out the pool from the loop. Multiply daily issue by the total days, then compare it with what you actually own. If you own far more than the formula says, the difference is sitting at customers or lost.
- Measure the loss rate per lap. Take the containers you bought in a year to replace ones that disappeared, and divide by the total number of container trips you sent out that year (daily issue Γ working days). Compare it with the ceiling in the table above for your price ratio.
- Keep an out-and-back ledger per customer. Containers left, containers collected, on every delivery. The difference is what that customer is holding, and it is the figure to raise with them.
- Put the empty count on the delivery signature. The same document that confirms the goods can confirm the empties exchanged. Who signs what at the dock is set out in whose job loading and unloading is.
- Agree a holding time with each customer, and a charge for containers not returned after it. A charge nobody expects to pay is the one that works.
- Cut the variety. One container size and one fill count per product. The rice case failed as much on two bag sizes and three fill counts as on anything else.
- Only then buy more containers, and buy the number the loop says rather than the number the shortage suggests.
The one sentence to remember
A returnable container is only as cheap as the number of times it comes back, so before you buy more, find out where the ones you already own are sitting and how many of them go missing every lap.