A poly mailer is a lightweight, opaque plastic shipping bag with a self-seal strip. No padding, no board, no box. For anything soft that cannot be crushed — apparel, textiles, bedding, printed matter, most soft goods — it is the lightest thing to ship and the fastest thing to pack, and it is waterproof in a way no paper mailer is.
It is the wrong choice for anything with corners, anything fragile, and anything that has to arrive presentable in its own right. Those go in a bubble mailer or a box. The rest of this page assumes you already know which of those three you need, and covers how to specify the poly mailer properly so the first order is the right one.
How to measure for a poly mailer
This is where most first orders go wrong, and it goes wrong in the same direction every time: people measure the item and order a bag that size, then discover the bag has to wrap around the item as well as cover it.
Lay the item flat, in the state it will actually ship in — folded, rolled, or boxed inside. Then:
- Width is the widest point of the item, plus its thickness, plus roughly half an inch of ease. The thickness matters because the film has to travel around the depth of the item, not just across its face.
- Length is the longest point, plus the thickness again, plus one and a half to two inches for the seal flap. The flap eats usable length, which is the single commonest reason a mailer arrives and does not quite close.
If you are shipping several sizes, measure the largest and check that the smallest does not swim in it. A bag with too much air in it creases the contents and looks careless on arrival, and on some carriers it can shift you into a worse rate band.
Standard sizes, and why they exist
Most of the industry works to a familiar ladder of sizes. They are worth knowing even though we cut to your dimensions, because if your product happens to sit inside one of them you will be in good company on availability and on carrier handling.
| 6 x 9 in | Jewelry, accessories, single garments folded small, documents. |
|---|---|
| 7.5 x 10.5 in | A single t-shirt, small soft goods, books. |
| 9 x 12 in | The workhorse. Most single apparel items land here. |
| 10 x 13 in | Two garments, hoodies, thicker knitwear. |
| 12 x 15.5 in | Multi-item orders, bulkier apparel, small homeware. |
| 14.5 x 19 in | Coats, multiples, larger textiles. |
| 19 x 24 in and up | Bedding, bulk apparel, anything that needs a gusset instead. |
Long, narrow items — rolled posters, curtain poles, some sportswear — need a long mailer rather than a wide one, and bulkier orders are usually better served by a gusseted mailer that opens out at the sides than by going up two sizes flat.
Film thickness
Poly film is quoted in mils, which is thousandths of an inch. Thicker film resists tearing and punctures better and adds to both material use and shipping weight. Most apparel and soft-goods mailers sit at the lighter end of the range; sharper contents, heavier loads and long courier routes move it up.
Co-extruded film is worth asking about, because it builds strength in layers rather than in bulk, so it can give more tear resistance at a lower gauge than a single-layer film of the same thickness. Tell us what is going inside, roughly what it weighs, and whether it has any corners, and we will put a number on it rather than leave you to guess.
Closures, and the one that saves you a second order
Every poly mailer has a self-seal strip under a peel liner. The decision worth making is whether you want a second adhesive strip below it.
The second strip is a returns closure. The customer opens the mailer along the tear line, puts the item back, and seals it with the strip you already paid a fraction of a cent for. If you sell apparel, where returns are a fact of the category rather than a failure, it removes the single most common reason a customer contacts you before returning something: they have nothing to put it in.
Printing on poly film sets different expectations
Poly mailers are printed flexographically, and the honest version is this: one or two strong spot colors on a colored film is where the format looks its best and where it runs cleanest. Full photographic artwork is possible but it is not what this substrate is for, and at the quantities most brands start with it rarely justifies itself.
Design accordingly. A logo, a wordmark, a repeated pattern and a strong background color will do more for the unboxing than a photograph printed at the limits of the process. If your artwork genuinely needs photographic reproduction, a printed box or a paper mailer is the better carrier for it.
Recycled, biodegradable and compostable
There are three different claims here and they are not interchangeable, so it is worth being precise before you print anything on the bag.
| Recycled content | Standard polyethylene film with post-consumer recycled material blended in. Behaves like a normal mailer. Usually darker or grayer than virgin film, which is a design constraint rather than a defect. |
|---|---|
| Recyclable | Ordinary poly mailers are polyethylene film, which is not accepted in most curbside programs but is generally accepted at store drop-off points that take plastic film. Saying “recyclable” without saying where is what gets brands criticized. |
| Compostable | A different material entirely, not polyethylene. Most compostable mailers require industrial composting facilities. Home compostable is a stricter and separate claim, and you should not print one when you hold the other. |
We will produce any of the three. What we will not do is help you print a claim the material does not support, because that is the one packaging decision that can cost a brand more than the packaging ever did.
Poly mailer, bubble mailer, or box
| Poly mailer | Soft, unbreakable contents. Lightest and fastest to pack. Waterproof. No protection against impact or crushing. |
|---|---|
| Bubble mailer | Small items that need cushioning but not rigidity. Books, cosmetics, electronics accessories, anything with a corner that would push through plain film. |
| Box | Fragile, rigid, or presentation-led. Anything where the packaging is part of the product experience rather than a way to move it. |
See custom bubble mailers for the cushioned version, poly bubble mailers for a bubble-lined poly outer, and custom mailer boxes when the shipment needs a box.
Bulk and wholesale orders
There is no minimum order, which is unusual in this format — most poly mailer suppliers start at a case quantity because the film runs are set up that way. A short run to test a size or a design before committing to volume is a normal order here.
Reorders run from the approved file, so a repeat matches the original without another proof cycle. Design is free, samples are free, and shipping is free.
What to send us for a quote
- The dimensions of the item as it will ship, folded or rolled.
- Its weight, and whether it has any corners or edges.
- How many sizes you need, if it is more than one.
- Whether you want a returns strip.
- Recycled content, compostable, or standard film.
- Your artwork, or a sketch. We will build the print layout around it at no charge.
More Custom Mailer Boxes
See the full Custom Mailer Boxes range, or explore related options with no minimum order and our best-price guarantee:
