Three Real Cost Items in Packaging—Volumetric Weight / Loading Rate / Pallet Layers: When a printing plant treats “making the box smaller” as a way to save money, which cost is it most likely to overlook?
💡 💡 At a Glance
Packaging void ratio is not a linear function but a function with inflection points, where the turning point occurs when the package can no longer fit or when the savings in shipping costs do not cover the additional assembly labor. There are three types of real-world calculations: ① volumetric weight is calculated from the outer dimensions (express delivery length × width × height ÷ 5000 or 6000, using the greater of this value and the actual weight), so gaps between stacked boxes and the thickness of the box walls must be included. Leaving a 5mm gap between boxes adds approximately 4.5% to the volumetric weight, meaning that the direction of cost savings often runs opposite to material savings. ② The loading rate is reduced during the packing process—buffering materials occupy 8%-15% of the volume, along with assembly allowances, instructions and certificates of conformity inside the box, and mixed-load batches. Measured void ratios are typically 5-8 percentage points lower than the design values, and fragile products have higher void ratios (when the spacing between ceramic cups is reduced from 15mm to 8mm, the damage rate rises from 2% to 7%). ③ Conversely, pallets constrain the box format—for 1200×1000 and European-standard 1200×800 pallets, an arrangement that does not divide evenly leaves an entire strip of unused space. A 600×400 box can accommodate only 2 per layer on a 1200×1000 pallet, with the number of layers constrained simultaneously by the container height of 2.6m and the maximum gross weight per pallet. In many cases, changing the box format to fully utilize the pallet is more effective than simply reducing the box size.
In April 2026, a customer manufacturing home appliance components came to us with a freight bill. The first thing they said was: “Your boxes are too roomy—you wasted 30% on shipping costs.”
He was right. We checked the data for the three batches he shipped to Europe:
First batch—the box dimensions follow the customer’s original design, with an inner diameter of 400×300×250mm, while the actual product dimensions are 360×260×210mm; shipping charges are recalculated based on volumetric weight.
Second batch—To save on materials, the customer had the box reduced to 370×270×220mm. Shipping costs decreased, but assembly labor hours increased.
Third batch — the customer reduced the dimensions again to 350×250×200mm, but it still didn't fit.
This is what the true cost-benefit calculation of void ratio looks like: it is not a straight line, but a function with inflection points, which usually occur when “the box shrinks to the point that it no longer fits” or when “it fits into the workstation, but labor costs exceed shipping savings.”
The first type of boundary: which dimensions are used to calculate volumetric weight
First, let’s talk about the most basic layer, which is also the easiest one to calculate incorrectly.
The billing weight for international express and sea freight is generally determined by the higher of the actual weight and the volumetric weight. Volumetric weight is calculated differently according to each carrier’s formula:
Here is the key point: volumetric weight uses the “outer dimensions,” specifically the combination of the longest side in each of the three directions—length × width × height, but in a fixed order. Do not use the shortest side as the width. Therefore, if a carton has dimensions of 400×250×180, it should be calculated as 400 × 250 × 180, not 400 × 180 × 250 (the result is the same, but it can be confusing if you assume that the “longest side” must always come first).
The real issue is: volumetric weight does not care about your “void ratio”; it only cares about the outer dimensions.
Our factory once conducted a particularly typical comparative test:
For the same batch of products, Customer A uses a box size of 400×300×250, with a 5mm gap left between stacked boxes; Customer B uses a box size of 400×300×250 but with no gap between stacked boxes. After packing:
Option A: Outer carton 400×305×255, with a volumetric weight coefficient of 6000.
Option B: Outer box 400×300×250.
Calculated, the volumetric weight of Option B is approximately 4.5% lower than that of Option A. It may not seem like much, but the customer ships in bulk via sea freight, and over the course of a year, that 4.5% amounts to a substantial financial impact.
So, when the printer discusses “how to save money” with the customer, the first question should be: “Will the savings come from packaging materials or from freight?”These two work in opposite directions—saving on materials often makes the box larger (because cushioning must be added), and a larger box means higher freight costs.
The second type of boundary: capacity utilization is lost during the packing stage
The second type of boundary is more practical: the porosity you design will shrink by the time it reaches the packing station.
After the product is placed in the box, there are still a few other items inside:
1. Cushioning materials. Cushioning components themselves occupy space and are often irregularly shaped. If molded paper pulp trays, twisted paper, or foam pads are used, their space utilization generally ranges from 8% to 15%; if stretch film, newspaper, or inflatable column bags are used instead, the fluctuation is greater.
2. Operating clearance. The assembler needs space to place the product inside the box, especially for irregularly shaped products. Additional clearance is required when workers press the box closed and snap on the lid.
3. Labels and instructions. Product instructions, certificates of conformity, and after-sales cards inserted in the box are generally counted as part of the packaging’s “non-product volume.”
IV. Batches and Traceability Codes. If a box contains multiple different SKUs, the gaps resulting from mixed packing will be magnified.
Our factory uses a rather straightforward but effective method to calculate the void ratio: during the packaging confirmation stage, we conduct a trial assembly using the actual product, measure the volume it occupies, and compare it with the space inside the box. This figure is typically 5 to 8 percentage points lower than the void ratio indicated on the customer’s design drawings.
This 5 to 8 point gap is the reason many “logistics-saving” solutions fail: customers calculate the void ratio using CAD, say “It’s only 12%, very tight,” then the actual result comes out at 18%, and they blame the packaging design.
There is also a counterintuitive point: lower porosity is not always better.
Our requirements for fragile products are exactly the opposite—fragile products need a high void ratio, because that space is reserved for cushioning materials; it is not wasted space, but protection. We once received an export order for ceramic mugs. In the customer’s initial design, they reduced the spacing between the mugs from 15mm to 8mm to save on freight costs, but the breakage rate upon arrival rose from 2% to 7%. The customer’s own calculations showed that the losses far exceeded the freight savings.
Therefore, when discussing the void ratio, the first question is: “What is the damage rate for this shipment, and who bears the liability for the damage?” If the cost of damage cannot be calculated, any savings on freight costs are meaningless.
The third boundary: the number of tray layers locks your box type in place
The third type of boundary is one that many people overlook, but it has the final say on export orders.
Export-order cartons ultimately have to be palletized. The number of pallet layers and the arrangement of cartons on each layer will, in turn, lock in the carton dimensions—it is not the cartons that accommodate the pallet; rather, the pallet dictates the carton dimensions.
The most common standard pallets are 1200×1000mm (Chinese standard) and 1200×800mm (European standard, commonly known as the "Euro pallet"). A 1200×1000 pallet is commonly arranged in a 2×2 layout with one extended position, or with 3 pallets placed along the 1000 direction. For 1200×800 pallets, the most common arrangement is 2 pallets, each 400 wide, or 3 pallets, each 266 wide, placed along the 800 direction.
The key lies in the two words “packed full”. There are two common forms of waste:
The first option: leaving a gap without accounting for its cost. Arranging 400×300 boxes in a 2×2 layout on a 1200×1000 pallet gives exactly 1200×600, leaving a 400mm gap in the 400 direction—the entire strip is pure waste. One layer holds 8 boxes, while the other holds 8 boxes but rests on a 400mm empty pallet, resulting in an effective loading rate of only 50%.
Second: the number of layers is capped at a certain figure. The number of pallet layers is limited by two factors: the height restriction (approximately 2.6m internal container height and approximately 0.15m pallet height) and the weight restriction (maximum gross weight per pallet, commonly 1000kg or 1200kg, as agreed by the customer and the shipping line).
Height is often overlooked. A 400×300×250 carton stacked 5 layers high reaches 1.25m. With a pallet, the total is 1.4m, still below 2.6m. However, with 400×300×500 cartons, 4 layers already reach 2m, and adding a pallet brings the total above 2.15m. Once partitions and stretch wrap are added, the stack is close to 2.6m. Often, adding one more layer to save on freight costs results in an excessive stack height, forcing you either to compress the goods or use an additional container.
Our factory's practice is to prepare a three-column comparison table of “pallet–carton type–number of layers” during the packaging design stage:
See the last line: 600×400 boxes on a 1200×1000 pallet allow only 2 per layer, leaving all the additional 600 space empty.Half a pallet's worth of space is simply wasted—unless the box dimensions are changed.
Therefore, the most effective version of “switching box types to save on freight” often means resizing the box to fill the pallet, rather than making it smaller. Changing 600×400×300 to 500×400×300 still allows four boxes per pallet, but improves volume utilization—the exact calculation depends on the customer’s actual pallet and container dimensions.
Summarize the three types of boundaries in a single table
When customers ask whether “the packaging can be made more economical,” what our factory gives them is not advice, but a form to fill out:
Only when all five figures are in place does “saving on shipping costs” become a calculable plan rather than just a statement.
One final thing, and the one most likely to be overlooked: who ultimately benefits from the freight savings? If the customer arranges logistics and the printer provides the shipment dimensions, the savings go to the customer. If the customer takes your proposal and negotiates a lower freight rate with the logistics provider, but the intermediary keeps part of the savings, the printer will not receive any additional orders as a result. This is not the printer’s concern, but it is worth mentioning in the meeting—because it determines whether the customer will continue to entrust the printer with calculating freight savings in the future.
Further reading
Read this alongside the chapters on the transportation ledger and cost ledger:
FAQ
How is volumetric weight calculated, using the internal dimensions or the external dimensions?
Use the external dimensions. A common courier formula is length × width × height (cm) ÷ divisor (5000 or 6000), with the charge based on the greater of the actual weight and the volumetric weight. For sea freight consolidation, chargeable tons are calculated by converting the cubic volume. Since volumetric weight is based solely on external dimensions, both the gaps left during stacking and the thickness of the boxes themselves must be included.
What is a reasonable packaging void ratio?
There is no universal value, as it depends on the product category. Fragile items require a higher void ratio because that space accommodates cushioning materials, while pressure-resistant, regularly shaped items can be packed more tightly. The key is that the design void ratio is typically 5-8 percentage points lower than the measured void ratio because cushioning materials, instructions, and assembly allowances all occupy space. Therefore, physical samples should be trial-packed and compared; relying solely on CAD is insufficient.
Will making the box smaller definitely reduce shipping costs?
Not necessarily. Shipping costs are calculated based on volumetric weight, so every millimeter reduced in the external dimensions lowers the cost. However, making the box smaller often requires adding cushioning material, which increases the occupied volume again. Assembly time may also increase. You should first ask whether the savings come from material costs or shipping costs, because these two factors often move in opposite directions.
How does the number of pallet layers limit box dimensions?
The number of pallet layers is limited by both container height and load weight. The container has an internal height of approximately 2.6m, while each pallet is about 0.15m high, less the space taken up by dividers and stretch film. Weight is constrained by the maximum gross weight per pallet, typically 1000-1200kg. Common standard pallet sizes are 1200×1000mm and the European standard 1200×800mm. The box dimensions determine how many boxes fit on each pallet layer, with any unfilled space representing a complete loss of capacity.
Why does the pallet determine the box style in reverse?
Because the number of boxes per pallet = the number arranged per layer × the number of stackable layers, and the number arranged per layer is determined jointly by the box length and width and the pallet dimensions, a box length and width that do not divide evenly into the pallet dimensions will leave an entire strip of unused space. For example, 600×400 boxes can only fit 2 per layer on a 1200×1000 pallet, leaving half the space completely empty. Changing the box design so that its dimensions fully cover the pallet is often more effective than simply making the box smaller.
Should the savings on shipping costs also be counted as part of the printing company's revenue?
Usually not. The customer or the customer’s logistics provider bears the shipping costs. The printer’s value lies in providing a practical, executable structural solution. The allocation of the benefits can be clarified during the meeting, because if an intermediary captures the shipping discount, the customer will not entrust the printer with this type of cost calculation again.
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