Load capacity
Day one is never the problem. Day thirty is.
Corrugated compression strength falls with time under load, with humidity, and with every forklift that brushes a corner. Safe stacking is a derating exercise, not a lookup.
Construction first÷4 for time−30% for humidityMatch the pallet
At a glance
- 01Quote request
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- 02Fulfilled by
- Partner suppliers
- 03Requests from
- Across the US
- 04Pricing
- By written quote
The procedure
Five steps from catalogue number to safe stack
Industry practice applies substantial safety factors. Bulk handling deserves the conservative end of every one of them.
Step 01
Start with construction
Take the rated compression strength for the actual construction: double, triple or five wall. Ask the supplier for it in writing.
Step 02
Divide for time
Storage beyond 30 days under load: divide laboratory compression by about four. This is the big one.
Step 03
Deduct for humidity
Above 70% RH, remove a further 25–35%. Corrugated has almost no wet strength.
Step 04
Deduct for handling
Hand-stacking or repeated forklift contact: a further 10–15% off.
Step 05
Then stack to that
Not to what the corner will physically bear on day one. Day one is not the problem.
Practical limits
Conservative rules of thumb
- Triple wall, loaded
- 2 high maximum
- Double wall, loaded
- 1 high — do not stack
- Five wall, loaded
- 3 high, matched pallets only
- Empty, nested
- 6 high
- Knocked down, flat
- To 60 inches of stack height
- Overhang tolerance
- Zero — footprints must match
“Two high loaded for triple wall. One high for double. Never on corners you have not looked at.”
The pallet
Where the load actually fails
Bulk packaging failures rarely start in the middle of a wall. They usually start at a vertical corner that lost its support because the pallet underneath was a different footprint, had a broken deck board, or had a nail standing proud through the top deck.
Match the footprint exactly. Inspect the top deck. Use #1 grade under anything stacked. If you are buying a Grade A container and putting it on a Grade B pallet, you have bought the wrong thing. Matched pallets can be added to the same quote request.
Where strapping crosses a vertical edge, add V-board. It is inexpensive and prevents one of the most common kinds of corner damage.
Tables
Capacity, height, pallets — the three that interact
A container is only as strong as the deck under it, so these three tables should always be read together.
| Construction | Thickness | Typical max weight | Stacking | Typical use |
|---|---|---|---|---|
| Single wall C | 5/32" (4.0 mm) | 65 lb | Not for bulk | Lids, layer pads, dividers |
| Double wall BC | 9/32" (7.1 mm) | 900 – 1,200 lb | 1 high loaded | General bulk under 1,200 lb |
| Double wall CC | 5/16" (7.9 mm) | 1,000 – 1,300 lb | 1 high loaded | Slightly better cushioning than BC |
| Triple wall BCC | 7/16" (11.1 mm) | 2,200 – 2,500 lb | 2 high loaded | The bulk workhorse |
| Triple wall ACC | 1/2" (12.7 mm) | 2,400 – 2,700 lb | 2 high loaded | Dense product with cushioning need |
| Five wall AAC | 5/8" (15.9 mm) | 3,000 lb+ | 3 high, matched pallets | Castings, stampings, export |
| Type | Size | Capacity | Notes |
|---|---|---|---|
| Recycled GMA #1 | 48 × 40 | 2,800 lb rack / 4,600 lb floor | No plugs, no companion stringers. Use under stacked loads. |
| Recycled GMA #2 | 48 × 40 | 2,500 lb rack / 4,000 lb floor | Up to three repaired boards. Floor-level staging. |
| Remanufactured | 48 × 40 and custom | 2,200 lb rack | Built from salvaged components. Heavier, variable deck gap. |
| ISPM-15 export | 48 × 40, 48 × 48 | 2,800 lb rack | Heat-treated, stamped, moisture checked below 19%. |
| Nestable plastic | 48 × 40 | 2,200 lb rack | Washdown and food environments; nests for return freight. |
| Presswood | 48 × 40, 45 × 45 | 1,500 lb floor | Light, nestable, effectively one-way. |
| Height | Cube | Fits | Best for | Watch for |
|---|---|---|---|---|
| 28" | 25.9 ft³ | Low-clearance racking, pick faces | Dense product, ergonomic sorting | Doubles your container count on light goods |
| 36" | 33.3 ft³ | Most standard racking | The default — best price and availability | Check reach height if hand-loaded |
| 40" | 37.0 ft³ | Cooler racks, harvest lines | Produce, bakery, mixed DC | Top-edge wear climbs with reach |
| 44" | 40.7 ft³ | Tall bays, textile sorting | Light bulky goods — foam, film, apparel | Hand-loading above 44" is uncomfortable |
| 48" | 44.4 ft³ | Dedicated tall programs | Very light, very bulky loads | Triple wall only; never stack loaded |
| Relative humidity | Duration under load | Strength factor | What to do |
|---|---|---|---|
| Below 50% | Under 30 days | 1.00 | Published stacking limits apply as stated. |
| Below 50% | Over 30 days | 0.25 – 0.30 | Divide laboratory compression by about four. |
| 50 – 70% | Under 30 days | 0.85 | Reduce stack height by one unit on marginal loads. |
| 50 – 70% | Over 30 days | 0.22 | Two high loaded becomes one high for double wall. |
| 70 – 85% | Under 30 days | 0.65 – 0.75 | Specify one construction up, or stop stacking. |
| 70 – 85% | Over 30 days | 0.15 – 0.18 | Do not stack loaded containers. Shorten dwell time. |
| Above 85% | Any | 0.10 – 0.14 | Fiber is the wrong container unless dwell is measured in hours. |
| Construction | First week | After 30 days | After 90 days | Notes |
|---|---|---|---|---|
| Double wall BC | 2 high | 1 high | 1 high, inspect weekly | Never stack a partly filled unit. |
| Triple wall BCC | 3 high | 2 high | 2 high, inspect weekly | Two high loaded is a common working figure that already allows for storage. |
| Five wall AAC | 4 high | 3 high | 2 – 3 high | Matched pallets only; check deck boards each move. |
| Empty, nested | 8 high | 6 high | 6 high | Above that the bottom scores compress and will not re-erect square. |
| Knocked down, flat | To 60 inches | To 60 inches | To 48 inches | Scores aligned, off the floor, indoors. |
| Product | Bulk density | Loaded weight | Construction | Notes |
|---|---|---|---|---|
| Mixed apparel, unbaled | 6 – 9 lb/ft³ | 200 – 300 lb | Double wall | Volume-limited. Buy tall, not strong. |
| Loose foam / film | 2 – 5 lb/ft³ | 70 – 170 lb | Double wall | 44 inch bodies pay for themselves here. |
| Cardboard offcuts | 7 – 12 lb/ft³ | 230 – 400 lb | Double wall | Keep dry or the weight is water. |
| Plastic regrind flake | 20 – 30 lb/ft³ | 660 – 1,000 lb | Double / triple | Static — specify antistatic liner. |
| Resin pellets (PE, PP) | 32 – 38 lb/ft³ | 1,050 – 1,250 lb | Triple wall | Octabin preferred above 1,200 lb. |
| PET flake | 22 – 28 lb/ft³ | 730 – 930 lb | Double wall | Abrasive — 5 mil liner minimum. |
| Apples / citrus | 30 – 35 lb/ft³ | 1,000 – 1,150 lb | Triple wall | Field heat and condensation; 40 inch is the produce default. |
| Potatoes / root crops | 38 – 45 lb/ft³ | 1,250 – 1,500 lb | Triple wall | Bottom-layer bruising — use a layer pad. |
| Frozen fruit / vegetable | 35 – 42 lb/ft³ | 1,150 – 1,400 lb | Triple wall | Manage the freezer-to-dock transition before stacking. |
| Grain / seed | 42 – 50 lb/ft³ | 1,400 – 1,650 lb | Triple wall | Octabin or bin — hoop stress matters. |
| Mineral powder | 55 – 75 lb/ft³ | 1,800 – 2,480 lb | Triple / five wall | At the top of what fiber should carry. Check the pallet. |
| Glass cullet | 80 – 95 lb/ft³ | 2,650 lb+ | Five wall | Fill to weight, not to height. Never fill to the top. |
| Metal stampings | 90 – 140 lb/ft³ | Fill by weight | Five wall + V-board | Sharp edges: burst strength and corner protection both matter. |
| Electronic returns, mixed | 10 – 16 lb/ft³ | 330 – 530 lb | Double wall | Mixed-height pools work best here. |
| Books / paper records | 35 – 45 lb/ft³ | 1,150 – 1,500 lb | Triple wall | Dense and deceptive — people routinely overfill. |
| Nuts / dried goods | 28 – 34 lb/ft³ | 930 – 1,120 lb | Triple wall | Gusseted liner, plus eight inches of height. |
| Measure | Imperial | Metric | Notes |
|---|---|---|---|
| Standard footprint | 48 × 40 in | 1,219 × 1,016 mm | The GMA pallet that standardised US distribution. |
| Triple wall thickness | 7/16 in | 11.1 mm | Takes about 7/8 in off interior width across both walls. |
| Typical capacity | 2,200 lb | 998 kg | Triple wall BCC, evenly distributed, matched pallet. |
| Container cube at 36" | 33.3 ft³ | 0.943 m³ | Outside dimensions, before board thickness. |
| OCC bale | 1,000 – 1,400 lb | 454 – 635 kg | Typical bale from a horizontal baler. |
| Trailer capacity, knocked down | 400 – 600 units | — | 53-foot dry van; cube limited, never weight limited. |
| Moisture ceiling for OCC | 12% | 12% | Above this you are selling water at a penalty. |
Diagnostics
Eight ways bulk packaging fails
Damage is evidence. Where it appears tells you whether the problem is the container, the pallet, the aisle or the weather.
| Failure | What it looks like | Cause | Prevention |
|---|---|---|---|
| Strap cut | Crushed line across a vertical corner, half an inch wide. | Polyester strap tensioned over an unprotected edge. | A V-board corner protector under every strap. |
| Forklift shear | Scuff outside, hollow feel inside over a six-inch band. | Lateral contact delaminating liner from medium. | Floor guides at pinch points; operator training. |
| Overhang crush | Failure at the bottom score, two corners only. | Container footprint larger than the pallet deck. | Buy pallet and container on the same quote. |
| Humidity creep | Bulging walls, leaning stack after weeks of storage. | Compression loss above 70% RH compounding under load. | Reduce stack height; one construction up; shorter dwell. |
| Condensation cycling | Soft outer liner after a freezer-to-dock move. | Surface below dew point for twenty minutes. | No stacking for 24 hours after a temperature transition. |
| Liner bridge | Uneven settle, container out of square after filling. | Flat liner bridging the corners under free-flowing product. | Gusseted liner sized to the footprint. |
| Dead score | Bottom flap will not hold its fold. | Repeated knock-down and re-erection, or wrong fold line. | Collapse along original scores only; train receiving. |
| Tine puncture | Paired holes about four inches above the base. | Tines entering at the wrong height on a stacked position. | Position signage and double-stack rules. |
Keep reading
The blogRelated reading
ECT, Burst and Stacking Strength
A plain-language guide to the three numbers printed in the box maker's certificate — and which one to actually use.
Read →How Used Gaylords Are Graded
A, B, C and D are not vibes. Here is what a careful grader looks at, in what order, and what gets rejected outright.
Read →Humidity, Gulf Warehouses and the Strength You Quietly Lose
Corrugated loses a meaningful share of its compression strength in high humidity. Most plants have never measured theirs.
Read →What Is a Gaylord Box, Really?
The container named after a Michigan paper company that became the standard bulk box of American warehouses.
Read →Capacity questions
Asked by every engineer
Why are used containers described by range rather than a single number?
Because a used board's measured strength depends on its history, and a single number implies a precision nobody can honestly offer on recovered fiber. The construction can be checked per unit; the range follows from the construction.
Can I stack a loaded gaylord on a partially filled one?
No. A partially filled container carries the load entirely on its walls with no internal support, and it will deform long before a full one. Stack full on full or not at all.
Does banding increase stacking strength?
Marginally, and only if the edges are protected. Unprotected banding cuts into the vertical corner and makes things worse. V-board first, then band.
What about cold storage?
Cold itself is fine; the condensation cycle when units move between temperatures is not. Specify one construction up, keep liners gathered rather than sealed, and do not stack during the first twenty-four hours after transfer.
How do I know what my warehouse humidity is?
An inexpensive hygrometer on a rack upright, read weekly for a month. It is cheap packaging engineering, and it often changes the specification.
Next step
Send the four inputs. Get the construction.
Weight, storage duration, humidity, handling. Add them to a free quote request and a partner supplier can recommend a construction.