Custom Poly Mailers

Choosing the Right Sizes

Poly mailers are measured by width and length, with the length excluding the seal flap. Choose a size that fits your products with a little room to spare, but not so much that they slide around. A T-shirt folded flat fits a small mailer, a hoodie or a pair of jeans needs a medium, and a coat or a bundle of items needs a large.

Most shops settle on three or four sizes to cover their range. It is worth measuring your bestsellers once folded and packed with any tissue paper or packing slip, so the size chart you order fits real parcels. If your products vary a lot, a gusseted mailer expands to take bulkier items.

Oversized bags are a common mistake. A small item rattling around in a large mailer looks careless, the excess film flaps about and can catch in sorting machines, and the customer may wonder why so much plastic was used. A well-fitted bag looks neat, protects the item better and is cheaper to buy. Bulky garments and bedding usually need large poly mailers for bulky items rather than a standard size.

Film Thickness and Strength

Film thickness affects strength and how opaque the bag is. Thinner film is lighter and cheaper, ideal for small, light items such as T-shirts and accessories. Thicker film resists punctures and tears better, so it suits heavier clothing, sharp-edged items such as boxed accessories, and bags that might be handled roughly.

Opacity matters too. A good poly mailer has a dark inner layer, often grey or black, that stops anyone seeing the contents through the bag. That protects your customer's privacy and discourages theft in transit.

If you are unsure which thickness to choose, start by thinking about the heaviest and sharpest item you post regularly. A pair of trainers in their box, a belt with a metal buckle or a bundle of denim will test a thin bag far more than a single T-shirt. We can quote two thicknesses side by side so you can compare, and many shops end up using a thinner film for small sizes and a thicker film for large ones. For items that need more protection than film can give, look at our corrugated literature mailers for flat goods.

Seals, Returns and Practical Features

Every mailer has a peel-and-seal strip with a strong adhesive that bonds the flap permanently. Once sealed, it cannot be opened without visible damage, which provides tamper evidence. For shops with lots of returns, a second adhesive strip and a perforated tear line let customers open the bag and reseal it for the return journey without hunting for tape.

Other handy features include a clear document pocket for packing slips or invoices, a pre-printed returns address and handles for larger bags. Some shops print a short care guide or a returns instruction on the back, which reduces customer emails.

Packing speed matters for busy shops. Mailers that arrive in neat, counted bundles, sorted by size, can sit in labelled trays beside each packing bench so staff grab the right bag without thinking. Peel-and-seal strips also mean no tape guns are needed, which keeps the bench clear and saves a step on every order. Brands that want an easy returns process can choose tear-strip poly mailers for returns with a second seal.

Getting the Look Right Alongside Other Packaging

Poly mailers often work alongside other branded items. Branded tissue paper inside the bag, a logo sticker sealing the tissue and a printed thank-you card turn a simple mailer into a polished unboxing. If you also use mailer boxes for fragile items, matching the colours and logo placement keeps your brand consistent whichever packaging the customer receives.

Remember that the courier label covers part of the bag. Leave a clear space on the front for the shipping label so it does not cover your logo.

Ordering Poly Mailers

Tell us the sizes, film colour, print colours and quantities, and we will send a custom quote by email within one working day. Minimums are quoted per job, so a small online shop can order branded mailers without committing to enormous stock. Printed mailers on larger runs start from £0.25 each.

We provide a free design proof showing your artwork on each bag size. Once you approve it, production takes 4 to 7 working days, and we deliver free and tracked across the UK mainland, usually in 2 to 3 working days. If any mailers arrive misprinted or damaged, report it within 10 days and we will reprint or refund. You can browse the full shipping and mailer box range if you send a mix of soft and boxed orders.