We're asked every week, usually with a hint of urgency: "Will the box hold?" And it's understandable – nobody wants to see the bottom of a box open up in the middle of a staircase or a pallet collapse in the warehouse.
The serious answer requires "it depends," but we'll give you some indicative numbers, explain what it truly depends on, and how to choose safely. If you're in a hurry and have a heavy load: double-wall cardboard boxes are your best bet.
The quick (and approximate) answer
| Cardboard type | Recommended weight inside | Typical use |
|---|---|---|
| Single wall | Up to 10-20 kg | E-commerce shipments, light products, domestic storage |
| Double wall (double flute) | Up to 20-40 kg | Moving, heavy or delicate shipments, warehouse stacking |
| Triple wall | Up to 60-70 kg | Industrial loads, export, pallet boxes |
These are conservative ranges: the exact figure varies with paper quality, box size, and how the load is distributed. We explain flute types in depth in our corrugated cardboard guide.
What determines if it holds (or not)
- The flute and grammage. More layers and more paper mean more resistance. Double wall isn't "a little" better than single wall: it's in a different league. And don't confuse corrugated cardboard with cardboard stock, which isn't designed for heavy loads.
- The size. For the same cardboard, a large box flexes more: the bottom acts like a bridge. That's why for dense items — books, tools, preserves — we recommend small boxes; there's more detail in the size guide.
- Humidity. This is the silent enemy: damp cardboard loses much of its strength. Store in a dry place, and if the shipment requires it, mark the box — the umbrella symbol exists for this, you can find it in the packaging symbols guide.
- Time. A box stacked for months experiences fatigue: the cardboard gradually yields under constant load. For long-term storage, over-spec the box.
Weight inside and weight on top: two different things
Just because a box can hold 25 kg inside doesn't mean it can support three 25 kg boxes on top. Stacking resistance depends on the walls (vertical compression), not the bottom.
Practical rules for stacking: heavy items always at the bottom, aligned columns (corners are the strongest part of the box), and if the stack is more than 3-4 layers high with a serious load, use double wall or a pallet. For warehouse stacks and palletized transport, you'll be interested in packaging levels and our palletizing guide.
How to reinforce a box that's just barely enough
- Tape in an H-pattern — all seams, not just the center. For the complete technique: how to tape to support more weight. With good tape: packaging tapes.
- Distribute the load: heavy items in the center and at the bottom, without overloading the bottom corners.
- Fill the empty spaces: a compact box resists stacking much better than a half-empty one, which dents and drags down the entire stack.
- And the human limit: above 15-20 kg, the problem is no longer the box — it's the person lifting it. Better two small boxes than one heroic one.
Frequently asked questions
How much weight can a single-wall box hold?
As a guide, between 10 and 20 kg, well-distributed, depending on quality and size. For loads near the limit or shipments with a lot of handling, switch to double wall.
Can I stack full cardboard boxes?
Yes, with good judgment: heavy items at the bottom, aligned corners, and moderate heights. Stacking resistance is in the walls and corners, not the bottom — and it plummets with humidity or poorly filled boxes.
What box do I need to ship 25 kg?
Double wall, moderate size, and H-taped. At TeleCajas, all boxes indicate their flute type on the product page; if you have doubts, write to us and we'll recommend the size and model.
Does tape make the box stronger?
The bottom, yes — a well-executed H-tape prevents most opening failures. What tape cannot do is compensate for cardboard insufficient for the load.
Better safe than sorry
At TeleCajas, we've been recommending the right box for each load for over ten years — neither too much nor too little. More than 40 sizes, 24-48h shipping to mainland Spain, Balearic Islands, and Portugal, and free from €30. Tell us what you're going to put inside: +34 665 53 23 58 (WhatsApp).
