Reference guide
Poly Mailer Size Reference
This is a lookup table rather than a method. If you already know what you ship and just want to know which size it goes in, start here and read across.
If you are working the decision out from first principles — measuring, testing, weighing against shipping bands — the size selection framework is the page you want instead.
Find your item, read across
Sizes assume a single item packed with a card and a returns slip. Add inserts or a second item and move up a row.
| What you ship | Start with | Move up if |
|---|---|---|
| Earrings, small jewelry, boxed | 6x9 | The box is deeper than a matchbox |
| Lipstick, serum, single cosmetic | 6x9 | It ships in a carton with a sleeve |
| Phone case, cable, small tech | 6x9 | You send several together |
| Sticker packs, cards, small prints | 6x9 | A board stiffener is needed |
| Socks, underwear, single thin item | 6x9 | More than two pairs |
| One folded t-shirt | 9x12 | You add tissue and a card |
| Paperback book | 9x12 | It is a hardback or oversized |
| Leggings, swimwear, light top | 9x12 to 10x13 | The order is routinely two items |
| Two-item apparel order | 10x13 | Either item is knitwear |
| Fine-gauge knit, light sweatshirt | 10x13 to 12x15 | It is heavyweight or oversized |
| Jeans, denim, chunky knit | 12x15 | Two garments travel together |
| Heavyweight or fleece hoodie | 14.5x19 | It is an oversized fit |
| Light jacket, three-garment order | 14.5x19 | You consolidate four or more |
| Bedding or towel set | 19x24 | It is a full double or larger set |
| Wholesale drop, batched returns | 19x24 | The load exceeds a comfortable carry |
| Cushion, folded quilt, square soft goods | 24x24 | Never — this is the square format |
Where an item sits between two rows, the smaller size is usually right, provided it seals onto clean film without the contents reaching the strip.
How to read this table honestly
Four caveats, all of which matter more than the table itself.
It assumes a complete order
Product plus card plus returns slip. If you also send tissue, a sticker sheet and a sample, move up.
It assumes a competent fold
A garment folded at speed occupies more room than one folded carefully. Size against the fold you actually get.
It says nothing about protection
Fitting and surviving are different questions. If contents are fragile, the format matters as much as the size.
Suppliers measure differently
Some quote to the flap, some to the usable area. Compare bags rather than numbers.
When the table is not enough
If your product does not appear here, or your order profile spans several rows, the answer is to measure a packed parcel rather than to pick the nearest match. Measuring a lofty or irregular item is less obvious than it sounds, and the method that works is set out in the mailer measurement guide, which covers packed depth as well as footprint.
Questions about the size reference
What is the most common poly mailer size?
Ten by thirteen, because it takes a folded garment, a two-item order or a garment plus inserts without a packer having to decide. That tolerance is why so many apparel operations standardise on it.
What size mailer fits a hoodie?
A standard unlined hoodie fits a 12x15 folded properly. Heavyweight, fleece-lined or oversized hoodies need 14.5x19, and forcing them into a smaller size puts the strain on the seal rather than the film.
Should I round up or down when between two sizes?
Down, provided the packed parcel seals onto clean film with the contents below the adhesive strip. An oversized mailer costs more and leaves slack air, which makes parcels less stable rather than safer.