Packaging is where a factory saves money without telling you. An under-built carton gets crushed on the water, a badly loaded container shifts in transit and damages your goods, and an unoptimized unit load leaves a fifth of your container empty while you still pay freight for it. This guide covers master carton design, unit load calculation, container utilization, carton marks, and the packaging specs to write into your tech pack.
Why packaging matters more than it appears
- A weak carton fails in transit, and the cost is not the carton — it is the damaged garments inside plus the ocean freight you paid for nothing
- Carton dimensions determine unit load, which determines how many units fit in a container
- Container space you do not use is freight money you have already spent
- Carton marks and labels are what customs, carriers, and your warehouse rely on to identify your shipment correctly
- Wood packaging (ISPM 15 compliance) has become a hard requirement in most destination markets
The packaging hierarchy
Apparel packaging has four layers. Each solves a different problem and each one can be specified in your tech pack.
Layer 1: Garment-level protection
- Tissue paper (15-25 gsm): separates garments to prevent abrasion and dye transfer
- Poly bag (0.03-0.05 mm): dust and moisture protection. Perforated for breathability
- Fold method: flat fold (tees, trousers), hanger fold (shirts, jackets), roll (knitwear, prevents crease)
- Size sticker: applied to the poly bag, must match the garment inside
Layer 2: Inner box (retail unit)
- Holds 6-24 garments in a printed or plain corrugated box
- Used when the customer will sell directly to end consumers (DTC unboxing experience)
- Adds 0.30-1.00 USD per garment in materials plus labor
- Not needed if your customer repacks for retail
Layer 3: Master carton
- Holds 30-100 garments or 4-20 inner boxes
- The main freight unit — everything above this is about protecting the master carton
- Where design decisions actually matter for shipping cost
Layer 4: Pallet and container load
- Master cartons stacked and strapped on a pallet, then loaded into a 20ft or 40ft container
- Strapping, corner protection, load distribution, and weight limits
Master carton design
Corrugated board grades
| Grade | Construction | Edge crush test | Typical use |
|---|---|---|---|
| Single wall (C flute) | 1 liner + 1 flute | 32 ECT | Lightweight garments, low stacking |
| Double wall (BC flute) | 2 liners + 2 flutes | 44-48 ECT | Standard apparel master cartons |
| Double wall (C flute) | 2 liners + 2 flutes | 61-68 ECT | Heavy garments (hoodies, jackets) |
| Triple wall (BC flute) | 3 liners + 2 flutes | 74-100 ECT | Long ocean transit, dense goods |
ECT (Edge Crush Test) is the standard measure of box strength, in pounds of force. For standard apparel under normal stacking, 44 ECT double wall is the workhorse. Below 32 ECT, boxes will crush under stack weight.
Sizing the carton
Carton dimensions should be derived from the garment fold, not chosen arbitrarily:
- Calculate the folded garment footprint first (length x width x depth)
- Add 10-15 mm clearance on each dimension for compression and handling
- Choose carton dimensions that stack efficiently in standard container dimensions
- Avoid cartons that leave large voids — you are shipping air
Standard carton sizes that work well for container loading: 600x400x450 mm, 600x400x500 mm, 600x400x600 mm, 400x300x400 mm. These divide cleanly into pallet and container footprints.
Flute direction matters
- C flute (4-5 mm thick): stronger in compression, larger external dimensions
- B flute (2-3 mm thick): better for smaller items, allows more units per carton
- Always specify flute direction on the PO — a factory substituting B flute for C flute changes the stack height and therefore the container utilization
Unit load calculation
A unit load is the number of garments in one master carton. It is the calculation that connects garment size, carton size, and container efficiency.
How to calculate
- Measure or compute the folded garment dimensions (L x W x T)
- Decide packing orientation (flat stack or folded upright)
- Divide carton internal volume by garment volume
- Apply a packing factor of 0.80-0.88 — never pack to 100% because void space is unavoidable
Worked example: t-shirt
| Parameter | Value |
|---|---|
| Folded t-shirt (size M) | 300 x 220 x 40 mm |
| Carton internal | 600 x 400 x 400 mm |
| Carton volume | 96,000,000 mm³ |
| Garment volume | 2,640,000 mm³ |
| Theoretical count | 36 pieces |
| At 0.85 packing factor | 30 pieces |
| Practical result (industry standard) | 30 pieces per carton |
Worked example: hoodie
| Parameter | Value |
|---|---|
| Folded hoodie (size L) | 400 x 320 x 90 mm |
| Carton internal | 600 x 450 x 500 mm |
| Carton volume | 135,000,000 mm³ |
| Garment volume | 11,520,000 mm³ |
| Theoretical count | 11 pieces |
| At 0.80 packing factor | 8 pieces |
| Practical result | 8-10 pieces per carton |
Why unit load affects your cost
Ocean freight is priced per container, not per garment. If your cartons hold 30 garments and the industry benchmark for that garment is 40, you are paying for 25% more container space than necessary.
- Typical apparel box-to-box efficiency range: 1,500-3,000 pieces per 20ft container (t-shirts), 700-1,200 pieces per 20ft (hoodies)
- Optimizing carton design from 30 to 36 units per carton reduces freight per garment by 15-20%
- This is one of the few places where packaging engineering directly reduces landed cost
Container utilization
Container dimensions
| Container | Internal dimensions (cm) | Volume | Payload |
|---|---|---|---|
| 20ft standard | 589 x 234 x 239 | 33 cbm | 28,000 kg |
| 40ft standard | 1203 x 234 x 239 | 67 cbm | 26,500 kg |
| 40ft high cube | 1203 x 234 x 269 | 76 cbm | 26,500 kg |
Note the counterintuitive point: payload decreases as volume increases for 20ft to 40ft because of axle weight limits. Apparel is light and volume-bound, so you will typically fill a container by volume, not weight — except for denim and heavy knitwear.
Standard carton footprint pattern
The most efficient loading pattern uses cartons that tile the container floor with no gaps. Two standard approaches:
- Column pattern: load cartons in vertical columns, front-to-back first, then stack sideways. Container width 234 cm accommodates two 117 cm carton widths
- Pinwheel pattern: alternate carton orientation 90 degrees to fill wall gaps. Slightly higher utilization but harder to unload
Standard master carton sizes that tile efficiently: 600x400x450 mm (two cartons across a 1200 mm container length) and 400x300x400 mm.
Target utilization rates
| Load type | Target utilization | Notes |
|---|---|---|
| Fully palletized, standard cartons | 90-95% | Best case; requires carton dimensions that tile evenly |
| Floor-stacked cartons | 85-90% | Common; leaves small gaps at container walls |
| Loose-loaded cartons | 75-85% | Poor load stability; only for very small shipments |
| Mixed carton sizes | 60-75% | Avoid unless unavoidable — the mixing destroys utilization |
Below 75% utilization, you are typically better off shipping LCL (less than container load) and consolidating with another shipper than paying for a half-empty FCL.
Load distribution and weight balance
- Heaviest cartons at the bottom and toward the front of the container
- Balance left-to-right to prevent the container listing during transit
- Do not exceed the container’s axle or suspension limits — overloading in one section damages the container and is the carrier’s right to refuse
- Mark the container with the max gross weight for road transport from port
Palletization
Pallet types
| Pallet | Dimensions | Use case |
|---|---|---|
| Standard export pallet | 1100 x 1100 mm | Default for ocean freight; fits container floors cleanly |
| Half pallet | 800 x 1100 mm | For narrower container doorways |
| Cargo pallet | 1200 x 1000 mm | European standard; matches EU warehouse racking |
| No pallet (floor stack) | n/a | Cheaper, less load stability, harder to unload |
Pallet standards
- EPAL / EUR pallet: 1200×800 mm, European standard, must bear the EPAL mark
- Export pallet: 1100×1100 mm, most common for China-to-US ocean freight
- ISPM 15: all wood packaging entering most countries (including the US, EU, Australia) must be heat-treated to 56°C for 30 minutes and bear an ISPM 15 stamp
ISPM 15 non-compliance is the single most common cause of shipment rejection at destination ports. Verify the stamp exists on every wooden pallet and dunnage piece before the container departs.
Strapping and load securing
- Polyester or polypropylene strapping: 12-19 mm width, 600-1,000 N breaking strength
- Corner boards (edge protection) on stacked cartons prevent crushing at the corners
- Stretch wrap for retail-ready loads that must remain intact through handling
- Fill void space with dunnage, air pillows, or empty cartons — never leave air gaps inside a carton row
- Container lashing points: use them. A load that can shift 10 cm in transit will damage cartons and contents
Carton marks and labeling
What must appear on every master carton
- Purchase Order number: your internal PO reference
- Style name and code
- Color name and code
- Size run breakdown (e.g. “S:10 M:25 L:30 XL:25 XXL:10”)
- Carton sequence number (e.g. “1/40”, “2/40” — carton X of Y total)
- Gross weight and net weight in kg
- Carton dimensions in cm
- Country of origin (“Made in China”)
- Number of units in this carton
Optional but recommended
- Barcode or QR code for warehouse scanning (GS1-128 or SSCC)
- Handling symbols (fragile / keep dry / this way up) — printed on at least two opposite sides
- Shipping marks (the shipper’s own reference for the forwarder)
- Cargo manifest reference for air shipments
Language and script
Carton marks should be in English (or a language your destination market’s customs authority accepts). For some markets, additional requirements apply:
- EU: marks in the language of the destination country may be required
- US: English is fine; CBP requires legible English
- Australia / NZ: English accepted, strict on wood packaging compliance
Placement rules
- Marks on at least two opposite sides of the carton (some cartons get rotated in handling)
- Stenciled or printed — hand-written marks are not acceptable for customs documentation
- Do not cover marks with shrink wrap or strapping
Common packaging mistakes that cost money
- Undersized cartons for heavy garments: hoodies and jackets in 32 ECT single-wall cartons crush under stack load. Specify 44 ECT double-wall minimum for anything above 250 gsm.
- Not specifying carton dimensions in the tech pack: the factory picks whatever is on hand, which may be 30% larger than optimal and quietly increases freight cost.
- Mixed carton sizes across styles: destroys container utilization. If you have 3 styles, ideally all three share the same carton footprint.
- No ISPM 15 verification: container rejected at destination port, storage fees accrue while you sort it out.
- Insufficient poly bag perforation: garments sweat in an airtight bag, developing mildew or odor in transit.
- Wrong fold method for the fabric: knits crease badly under flat fold; they need rolling or hanger folding.
- No carton sequence numbering: your warehouse cannot verify it received all 40 cartons. This is a real problem with retail shipments.
- Shipping air when sea would work: air freight costs 3-5x more per garment. For non-urgent orders, sea is almost always correct.
- Failing to check container utilization before loading: ask for the loading plan or photos before the container is sealed.
How to specify packaging in your tech pack
Include a dedicated packaging section with:
- Garment-level: poly bag specification (thickness, perforated or not), tissue paper or not, fold method, size sticker format
- Inner box: yes or no, carton material, print or plain, units per inner box
- Master carton: exact dimensions (L x W x H in mm), board grade and ECT, flute type, units per carton
- Carton marks: list every required field with format examples
- Palletization: pallet type or floor stack, strapping specification, corner board requirement
- Weight: expected gross weight per carton
Request a photo of a packed and marked carton before bulk completion, and a photo of the loaded container with the door closed and the seal number visible before the container departs.
FAQ
How many units should be in a master carton?
There is no universal answer, but practical guidance: (1) keep cartons under 25 kg gross weight for manual handling, (2) choose carton footprints that tile standard container dimensions, (3) target carton dimensions that stack to under 2.3 m (container interior height), (4) round numbers like 30 or 40 units are easier to reconcile than 37. Your factory will have standard carton sizes for common garments — ask what they already run.
What is a “master carton” versus an “outer carton”?h3>
They are the same thing. Industry terminology varies: “master carton”, “outer carton”, “export carton”, “shipping carton” all refer to the main freight box. “Inner carton” and “retail box” refer to the smaller box inside it. Consistency in terminology prevents miscommunication with factories that use different conventions.
Does packaging affect garment quality?
Yes, significantly. Poor packaging causes: abrasion between garments (visible on dark fabrics with lighter garments touching), dye transfer from undyed fabric, creasing from compression, moisture damage from non-perforated bags, and crushing from inadequate board grade. For light-color or delicate fabrics, tissue paper is not optional.
How much does packaging cost per garment?
Typical ranges for standard apparel:
- Poly bag only: 0.05-0.20 USD
- Tissue paper + poly bag: 0.10-0.30 USD
- Inner retail box: 0.30-1.00 USD
- Master carton (allocated per garment): 0.05-0.25 USD
- Pallet (allocated per garment): 0.02-0.10 USD
Total for standard export packaging (poly bag + master carton + pallet): 0.12-0.55 USD per garment. DTC retail packaging with an inner box roughly doubles this.
What is the difference between master carton gross weight and net weight?
Net weight is the garments only. Gross weight includes the poly bag, carton, and any packaging material. Customs and carriers need both: gross weight determines freight charges and handling equipment requirements, net weight determines duty valuation on some destinations. A mismatch between the packing list and actual gross weight is a common cause of carrier charges and customs queries.
Should I require a specific board grade from the factory?
Yes, if you are shipping long-distance ocean freight or stacking cartons high. Specify at least “double wall, minimum 44 ECT” in your tech pack. For short-haul or air freight, single wall C flute is acceptable. If the factory offers to upgrade at low cost for long ocean transit, it is usually worth taking.
How do I verify the container was loaded properly?
Request three things before the container departs: (1) a loading plan showing carton positions and total carton count, (2) photos of the loaded container from the rear before the door closes, (3) the container seal number and a photo of the sealed door with the seal visible. If the factory will not provide these, treat it as a warning sign for a first order.
What happens if cartons are damaged on arrival?
Photograph the damage before unpacking, note the container seal number and whether it was intact, and record the carton sequence numbers affected. Report to the carrier within the contractual claims window (typically 7-14 days for ocean freight). If cargo insurance was purchased, file the claim with the survey report. This is why photographs at loading and at arrival are both important — they establish the chain of custody.
How this fits the buyer journey
Packaging is the final layer before your goods leave the factory:
- How to Write a Tech Pack — the packaging section belongs in the tech pack from day one
- Step 3: Bulk Production — the finishing and packing sub-stage
- Shipping: FOB vs CIF vs DDP — packaging determines container utilization and therefore freight cost
- Trims and Labels — size stickers and carton marks are part of the trim set
- QC and AQL Guide — packaging verification belongs in pre-shipment inspection
How we work at Kemondo
At Kemondo Apparel, we run standardized carton footprints across our production lines so mixed-style orders load efficiently in a single container: 600x400x450 mm for tops and 600x450x500 mm for hoodies. All wood packaging carries valid ISPM 15 stamps, verified before the container is sealed. Every carton is marked with PO number, style, color, size breakdown, carton sequence, gross and net weight, dimensions, and country of origin, printed rather than hand-written. We send you a loading plan plus photos of the loaded container and the sealed door before the container departs, and our standard cartons are double wall 44 ECT or higher for ocean freight. For DTC clients we offer printed inner retail boxes with tissue paper and custom size stickers, quoted as a separate packaging line so you can see the cost impact per garment.
Want to optimize your packaging and container utilization? Message us on WhatsApp with your order quantity, garment types, and destination port. We usually reply within 12 hours with a carton plan and an estimated container utilization figure.