One Extra Day of Dwell Time: The Hidden Cost in Your Returnable Packaging Pool

One extra day at your customer can mean thousands of euros in additional packaging investment.

The reason is simple: every day a returnable container remains unavailable, you need more containers to
keep the same logistics flow running.
If your operation uses 200 containers per day, one additional day in the cycle can require roughly 200 extra
containers.
At €100 per unit, that is €20,000 in extra fleet investment — before buffer stock or repair reserve.
Try it with your own numbers
Enter your shipment frequency, transport time, customer dwell time and packaging type in our free
calculator:
ZAMKO Returnable Packaging Pool Size Calculator
Try changing customer dwell time by just one or two days and see what happens to the required fleet.
A simple example
Imagine a manufacturer uses an average of 200 returnable containers per day.
If one complete circulation cycle takes 10 days, approximately 2,000 containers are required simply to keep
those movements running.
Now assume nothing else changes: the same shipment volume, the same customers, the same transport
distance and the same packaging.
But the customer keeps the empty packaging for one additional day before making it available for return.
200 containers/day × 11 days = 2,200 containers
That single additional day ties up another 200 containers.
At €100 each, that represents approximately €20,000 of additional packaging investment.
And that is before adding safety stock, repair reserve or other operational buffers.
This is why dwell time should be treated as a financial variable, not only as an operational detail.
The important metric is not annual volume
Annual shipment volume alone is not enough to determine the right size of a returnable packaging pool.
What matters is how many units are needed every day — and how long each unit is unavailable before it
can be used again.
Daily packaging demand × total cycle time = active circulation

The complete cycle can include:
✅outbound transport time
✅customer dwell time
✅waiting for empty packaging to accumulate
✅ return transport time
✅inspection, cleaning or internal handling before reuse
On top of this active circulation requirement, most operations also need an additional buffer for peaks and
delays, plus a reserve for damaged, lost, repaired or temporarily unavailable packaging.
An empty container waiting at your customer's warehouse is still working capital that cannot be
used elsewhere.
What happens if dwell time changes?
At the active-circulation level, the effect is straightforward. If you use 200 containers every day:
Total cycle time Daily requirement Active circulation Extra units vs. 10 days
10 days 200 2,000 —
11 days 200 2,200 +200
12 days 200 2,400 +400
14 days 200 2,800 +800
At €100 per container, increasing the cycle from 10 to 14 days represents another 800 × €100 = €80,000 of
packaging before adding operational buffer and repair reserve.
This is why even small improvements in the return cycle can have a significant financial effect.
What would this mean for your operation?
Instead of working it out manually, you can enter your own logistics data: shipment frequency, transport
distance, customer dwell time, return frequency, packaging type and safety buffer.
Try the calculator here: https://zamko.eu/returnable-packaging-pool-size-calculator/
Full-truck returns create another trade-off
For collapsible returnable packaging, companies often wait until enough empty units have accumulated to fill
a complete return truck.
This normally reduces the freight cost per returned unit.
But every day spent waiting for enough empties to accumulate also extends the cycle.
And every additional day increases the number of containers required in the overall pool.
A larger return batch can reduce transport cost but increase packaging investment.
Smaller and more frequent returns can do the opposite: lower the required packaging pool, but increase
return freight costs.
Neither strategy is automatically better. The optimum depends on shipment frequency, collapsed return
capacity, transport distance, packaging value, customer dwell time and the stability of the logistics loop.
This is one reason why returnable packaging should be evaluated as a complete logistics system, rather
than simply as a container purchase.

Why procurement should look beyond unit price
Procurement teams naturally focus on the price of each container. But the number of containers required
can be just as important as the price per unit.
Option A: €90 per container × 2,500 containers = €225,000 fleet investment
Option B: €105 per container × 2,000 containers = €210,000 fleet investment
The €90 container is cheaper. But the total packaging fleet is more expensive.
This can happen when differences in fold ratio, return transport, handling, dwell time, cycle speed or
durability change the number of units required to operate the system.
The objective should therefore not be: buy the cheapest returnable container. It should be: create
the lowest-cost reliable packaging loop.
Measure dwell time before committing capital
Before purchasing hundreds or thousands of returnable containers, companies should establish the key
parameters for each important transport lane:
▪️ daily packaging requirement
▪️ outbound transport time
▪️customer dwell time
▪️ return frequency
▪️FTL or LTL return strategy
▪️number of collapsed units per return vehicle
▪️required operational buffer
▪️defect and repair reserve
Even modest improvements can have a substantial financial effect.
If a company uses 200 containers per day, reducing customer dwell from seven days to five removes
approximately 2 × 200 = 400 containers from the active circulation requirement.
Conversely, a return process that gradually becomes slower can quietly increase the required fleet even
though shipment volume has not increased at all.
Calculate before you buy
ZAMKO developed the free Returnable Packaging Pool Size Calculator so procurement and logistics teams
can test these variables before committing capital.
You can enter your own shipment volume, transport time, customer dwell time, return strategy, packaging
system and safety buffer, then see how changing those assumptions affects the required packaging pool.
Try your own scenario: ZAMKO Returnable Packaging Pool Size Calculator
The key question is not only: “How many containers are we shipping?” It is: “How long is each
container unavailable before we can use it again?”
Finding one unnecessary day in that cycle can sometimes be worth far more than negotiating another few
euros off the purchase price.