How to choose between 3, 5 and 7 ply boxes

"Ply" is the number of paper layers in a corrugated board. More layers, with more fluted (wavy) layers between flat liners, means a stronger and stiffer box. Choosing the right ply protects your product and avoids paying for strength you do not need.

What 3, 5 and 7 ply mean

Start with the packed weight

As a general starting guide (not a guarantee): up to about 5 kg suits 3 ply, roughly 5 to 15 kg suits 5 ply, and above about 15 kg is where 7 ply is usually considered. The exact board depends on box size, because a larger box with the same load needs more strength.

Five things that change the answer

• Weight and box size: a big box is weaker per square centimetre than a small one.
• Fragility: breakable items need strength plus cushioning, not strength alone.
• Stacking: boxes at the bottom of a pile carry everyone else's weight.
• Distance and handling: more transfers and long routes mean more knocks and drops.
• Moisture: damp storage or transit softens board, so a higher ply gives a safety margin.

Common mistakes

• Choosing only by lowest price and paying later in damaged goods.
• Using a much larger box than needed, then filling the gap with paper.
• Using 3 ply for a heavy item because the first sample "felt fine" on a table.

What to tell us for a quotation

Share the product, its packed weight, the inside size you want, how it travels and whether it is stacked. We suggest a ply and confirm the board specification, price and lead time in writing. You can also ask the assistant on this page for a quick starting suggestion.