Poly Mailer Sizes: Complete Dimensions Chart (All Standard Sizes)

Quick answer: Poly mailer sizes run from 6" × 9" to 24" × 24", listed as width × length, measured flat and closed. The most common size is 10" × 13", which fits one adult T-shirt. A 12" × 15.5" fits hoodies and jeans. A 14.5" × 19" handles bulky or multi-item orders. Most clothing ships in 2.5 mil film.

*Last updated: October 2026.*

Poly mailer sizes look simple until a box of 1,000 arrives and your hoodie won't fit. The printed size is usually the outside flat measurement, not the room inside. This guide gives the full chart, the thickness tiers, and a fit rule you can test with a single sample.

Poly Mailer Size Chart

Suppliers disagree by a fraction of an inch, so treat every figure as a typical value.

Key takeaway: Pick the size from your folded product, not from the tag size on the garment.

How Poly Mailers Are Measured

Poly mailer dimensions are written width first, then length. Lay the empty mailer flat. Measure across the opening from seam to seam, then from the bottom seam to the flap fold.

The adhesive flap is where suppliers differ. Many leave it out of the listed length. Others include it. The flap often adds roughly 1.5 to 2 inches. A mailer listed with the flap can be that much shorter inside.

Then there's flat size versus usable interior. One supplier lists its 10" × 13" mailer as about 9.5" × 13" inside. The seams eat the difference. Always ask whether a listing quotes exterior or interior numbers before you order in bulk.

How to Measure Your Product for Poly Mailer Sizes

Fold the item exactly how you'll pack it. Then measure three things: width, length, and thickness. Include tissue, a thank-you card, or any retail bag.

Here's the rule of thumb I give people. Add about 2 inches to the length so the seal stays clear of the product. Add roughly 1 inch to the width, plus the product's thickness, so it slides in without a fight. A folded tee at 8" × 10" × 1" lands on a 10" × 13" mailer. It's a guideline, not a spec, so test it.

My advice: pack one real order in a sample mailer before you buy in bulk. A mailer sized to the product alone can leave the seal strip short of the fold.

Poly Mailer Thickness Tiers

Thickness is measured in mils. One mil is 1/1,000 of an inch. Thicker film resists punctures and tears better. That's the only general claim worth making, because the exact load limits depend on the film and the carrier.

Some suppliers go thicker still. You'll feel it right away. 3 mil film has a stiffer, almost papery snap. A 2 mil bag feels floppy. If your item has a zipper, a hard corner, or a buckle, I'd go thicker and not argue about it.

Poly Mailer vs Bubble Mailer vs Mailer Box

A poly mailer is the lightest and cheapest-to-store option. It protects against water and scuffs, but not crushing. That's the honest trade-off: you give up structure for weight and space.

A bubble mailer adds a layer of cushioning for small, breakable goods. A mailer box adds a rigid shell, which suits gift sets and anything that can't be squashed. Our mailer box sizes guide covers that format in detail.

My opinion: if a customer pays for it and opens it as a gift, use the box. If it's a shirt headed to a closet, the poly mailer wins.

How to Pick Your Poly Mailer Size

Start with your top ten products. Fold each one the way you ship it. Run the rule above, and you'll usually land on just two or three poly mailer sizes.

When a product falls between two sizes, size up. A snug mailer strains the seal. Also leave room for a shipping label on the largest flat face.

Check the broader box size guide if some products belong in a carton instead. Our shipping box sizes chart helps with those. The envelope sizes chart covers flatter, document-style items.

Opaque, Clear, and Custom-Printed Poly Mailers

Opaque mailers hide the contents and are the default for apparel. Many have a lighter outside and a darker inner layer, so a bright garment doesn't show through. Clear bags suit retail display and prep work, but they don't hide a thing.

Custom-printed mailers carry your logo or pattern. They look better on a doorstep, and they cost more per unit than plain stock. That's fair for a brand shipping direct to consumers. It's overkill for a seller moving a few boxes a month.

Custom Poly Mailer Sizes

Standard poly mailer sizes cover most apparel. Odd products don't fit them: a rolled yoga mat, a folded garment with a hanger, or a three-item set.

Easy Box Packaging cuts packaging to your exact spec, and many products start from 50 units. Our flexible mailers category lists a custom bio poly mailer for apparel and non-fragile goods. It also lists custom t-shirt bags. For a rigid option, see our mailer boxes. Standard sizes are the starting point. We custom-cut to your measurements.

Standard production is 7 business days after approval, with rush from about 4 days. The quote confirms the final timing and specification.

Poly Mailer Sizes and Shipping Cost

An oversized mailer can push a parcel into a higher billing tier, because carriers may charge on dimensional weight. A right-sized mailer costs less to ship and wastes less film. Our guide to right-sized packaging and dimensional weight explains the math.

Carrier rules and supplier specs change. Verify them at the carrier's own site before shipping. The USPS Domestic Mail Manual is the official reference for mail standards.

Poly Mailer Sizes FAQ

What is the standard poly mailer size? The 10" × 13" poly mailer is the most common standard size. It fits one adult T-shirt or a few folded tees.

What size poly mailer fits a T-shirt? A 10" × 13" mailer fits one adult T-shirt in sizes S to L. Kids' and slim tees fit a 9" × 12", and XL tees go in a 12" × 15.5".

What size poly mailer fits a hoodie? A 12" × 15.5" mailer fits most S to L hoodies folded flat. XL and XXL hoodies usually need a 14.5" × 19".

What size poly mailer fits jeans? A 12" × 15.5" mailer fits one pair of standard jeans. Thin or kids' denim can go in a 10" × 13".

How thick should a poly mailer be? 2.5 mil is the usual choice for clothing. Step up to 3 mil for denim, zippers, or heavier items, since thicker film resists punctures better.

Are poly mailer sizes measured with the flap? It depends on the supplier. Many leave the adhesive flap out of the listed length. The flap is usually 1.5 to 2 inches, so confirm first.

Is a 10x13 poly mailer 10 inches wide or tall? The first number is width. A 10" × 13" mailer is 10 inches across. It's 13 inches from the bottom seam to the flap line.

What is the rule for choosing a poly mailer size? Add about 2 inches to the folded length. Add 1 inch plus thickness to the width. It's a rule of thumb, so test one sample.

Choosing Poly Mailer Sizes

Poly mailer sizes come down to one honest step: fold, measure, add the margin, and test a sample. Most shops need only two or three sizes. Order those, and skip the guesswork.

Product doesn't fit a standard size? We custom-cut every box to spec — get a free quote.