Box Liners 101: Protecting Products Inside Corrugated Boxes

Corrugated boxes protect products from impact, but they do nothing against moisture, dust, or contamination. That is where box liners come in — a poly bag inserted inside the box that creates a sealed barrier between your product and the environment.

Why Use Box Liners

• Moisture protection — Poly liners prevent humidity, rain, and condensation from reaching products inside cardboard boxes. Critical for food, paper goods, and hygroscopic materials.
• Dust and contamination — Keeps contents clean through warehouse storage and transit. Important for medical, food, and cleanroom applications.
• Leak containment — For liquid or semi-liquid products, a box liner contains spills within the box rather than damaging other shipments.
• Product separation — Liners prevent direct contact between the product and corrugated cardboard, avoiding fiber contamination or ink transfer.

Sizing Box Liners

A box liner should be slightly larger than the interior dimensions of the box. Measure the box interior length, width, and height. The liner bag width should equal the box length plus depth plus 2 inches. The liner bag length should equal half the box perimeter plus the box height plus 3-4 inches for fold-over.

We manufacture box liners in any size to fit standard and custom box dimensions. Send us your box dimensions and we will calculate the right liner size.