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What the ply count means
Corrugated board is made of flat paper liners and fluted (wavy) paper glued between them. The ply count is the total number of paper layers. 3 ply is two liners with one flute between them. 5 ply is three liners with two flutes. 7 ply is four liners with three flutes. Each extra flute adds thickness, stiffness and crush resistance, and also weight and cost.
3 ply: standard e-commerce boxes
3 ply is the board used for most e-commerce shipping boxes, mailer boxes and folding cartons, including every box we sell. It is light, folds cleanly along its creases, and protects products that are not heavy or fragile: apparel, books, cosmetics, boxed accessories and small electronics. Its single flute gives enough cushioning for courier handling without adding much to the parcel weight that couriers charge on.
5 ply: heavier and stacked loads
5 ply adds a second flute. Use it when the carton carries real weight, holds something fragile such as glassware or ceramics, or will be stacked in a warehouse or vehicle where the boxes underneath take the load. We stock 5 ply as flat corrugated sheets; 5 ply shipping boxes are available on request through the quote form.
7 ply: heavy and export shipments
7 ply has three flutes. It is used for heavy industrial goods, machinery parts and export cartons that travel in containers and are stacked high. For a typical online order it is more board than the product needs. We stock 7 ply as flat corrugated sheets.
Choosing by the job
- Single light product, courier delivery: 3 ply box, or a courier bag if nothing can be crushed.
- Fragile product or several heavy items in one carton: 5 ply, or 3 ply with corrugated sheets as dividers and padding.
- Boxes stacked in storage or transit: 5 ply for the cartons at the bottom of the stack.
- Export or heavy industrial goods: 7 ply.
- Not sure: send the product weight and dimensions through the quote form and we will suggest a board.