Bubble Mailer Size Guide

Bubble mailer sizes use a numbering convention that is universal in practice and standardised nowhere. Here is what the numbers mean and how to choose between them.

The sizes

Measuring correctly

The listed dimensions are the usable internal area, measured to the seal line rather than the edge of the bag. Two consequences follow.

First, allow roughly 15 mm of headroom above your product so the flap can fold and seal cleanly. A product that reaches the seal line will not seal reliably.

Second, thickness eats width. A mailer is a flat bag; a 30 mm-thick product consumes roughly 30 mm of the stated width as the bag wraps around it. For anything with real depth, size up.

The letterbox question

#000 and #0 will usually clear a standard letterbox gauge if the contents are thin. From #2 upward, treat the parcel as a parcel. Letterbox delivery is worth designing for where it is available — it removes failed-delivery attempts entirely, which is one of the more expensive things that can happen to a small parcel.

When to use something else

• Books and flat printed goods — a book wrap holds them rigid and posts flatter.
• Soft goods needing no padding — a poly mailer costs a third as much.
• Single-material recyclability — kraft paper mailers, since a bubble mailer’s lining has to be separated from its outer.

Standardise where you can

Most catalogues fit into two bubble mailer sizes plus one exception. Two sizes gets you better quantity pricing, a simpler bench and less stock sitting still. Work out which two by packing your top ten SKUs and seeing where they land.

Measure your product, add the clearances above, and check the result against the millimetre dimensions in the table. If you are between two sizes, ask us before committing to a minimum order.