Poly mailer sizes and cost: right-size the bag, not the box

A mailer costs more when it is too big than when it is too small: dimensional-weight charges scale with volume while the bag adds grams and film. This guide walks the sizing math and the cost levers that matter for e-commerce shippers.

Measure the product, not the box it came in

Mailer sizing starts from the packed product dimensions plus handling room: about 2 cm of slack on length and width so the product is not fighting the bag, and enough gusset or width to take the thickness. An under-sized bag splits at the seal; an over-sized one pays dimensional weight for air.

The dimensional-weight trap

Carriers price by the greater of actual and dimensional weight, so a mailer that is 10% too long can push a light apparel item into the next price tier. Sizing to the product - not to a default envelope - is often a bigger saving than shaving bag price.

What moves the unit cost

Film thickness, size, PCR content and print drive cost in that order. Standardising to two or three sizes across your catalogue, keeping plain interiors printable, and ordering consolidated volumes each month lets a factory price you for repeat rather than one-off runs.

Seal strength and puncture resistance

A mailer only needs to survive the journey. Tear-resistant film and a full-width adhesive seal cover most shipments; reinforced or bubble-lined mailers are worth the cost only for fragile, high-value items - otherwise the extra weight and volume are pure dimensional-weight loss.

Ordering for e-commerce scale

For brands shipping thousands a month, we hold your sizes and artwork on file: reorders are repeatable, printed and plain share the same line, and stock turns into production rather than inventory risk.

Frequently asked questions

How do I know which mailer size I need?

Measure the packed product, add ~2 cm slack on length and width, and confirm thickness allowance; we also provide a size chart against product dimensions.