Poly mailer sizes run from 6 x 9 inches to 19 x 24 inches, measured flat as width x length. The 10 x 13 poly mailer is the most common size. It fits one adult T-shirt or up to about five folded shirts. The 12 x 15.5 covers hoodies, sweaters, and jeans. A 14.5 x 19 handles bulky items and multi-item orders. For poly mailer thickness, 2.5 mil is the standard for clothing.
This guide covers the full size chart, the best sizes for clothes, thickness by product, and how to measure before you buy in bulk.
What are Poly Mailers
Poly mailers are self-sealing shipping envelopes made from polyethylene film. They are light, water resistant, and tear resistant. They suit soft goods like apparel, accessories, and books that do not need a rigid box.
How to Calculate Poly Mailer Size Dimension
Sizing takes two measurements: the mailer and the product going in it.
Measure the mailer
Lay the empty mailer flat. Measure the width from seam to seam across the opening. Measure the length from the bottom seam to the flap fold line. Leave the adhesive flap out of the number. Check whether your supplier lists interior or exterior size.
Measure your product
Fold the item exactly as you will pack it. Measure length (L), width (W), and thickness (T) in one unit. Include tissue, inserts, and any retail polybag.
Apply the sizing formula
A flat mailer wraps both faces of the product. Each side of the bag loses about one full thickness.
- Minimum mailer width = W + T + 1 inch
- Minimum mailer length = L + T + 2 inches
The extra inch on width makes loading easy. The extra two inches on length keep the seal clear of the product.
A folded adult T-shirt at 8 x 10 x 1 inches needs a 10 x 13 mailer. A folded hoodie at 9 x 12 x 1.5 inches needs 11.5 x 15.5, so the 12 x 15.5 fits. When you land between two sizes, size up.
Measure the filled package for postage
Carriers bill the higher of actual weight and dimensional weight. Measure the sealed package at its longest, widest, and thickest points. Run those numbers through the DIM weight formula before you lock in a size.
Pack-test before bulk ordering
Order samples in your top two sizes. Pack real inventory and check the seal, label space, and presentation.
Types of Poly Mailers (Based on Material)
The material of your plastic mailers influences how strong, costly, and environmentally friendly they are.
Picking the right size while considering these factors enhances your packaging strategy.
That way, your packages will come safely, your business will run easily, and your customers will enjoy opening their packages. Consider these kinds of keys:
| Type | Best for | Trade-off |
|---|---|---|
| Standard polyethylene | Apparel, books, soft goods | Lowest cost per unit |
| Recycled content (PCR) | Brands with sustainability goals | Small price premium |
| Compostable (PLA/PBAT) | Eco-focused brands | Needs industrial composting |
| Bubble-lined | Cosmetics, small electronics | Heavier and costlier |
| Colored or metallic | DTC unboxing, social sharing | Higher unit cost |
| Tamper-evident | High-value items | Higher unit cost |
What are the Most Commonly Preferred Poly Mailer Sizes
Poly Mailer Size Chart: Standard Dimensions
All poly mailer dimensions are listed as width x length, measured flat, without the seal flap.
| Size (in) | Size (cm) | Best for | Typical thickness |
|---|---|---|---|
| 6 x 9 | 15 x 23 | Jewelry, socks, phone cases, samples | 2 to 2.5 mil |
| 7.5 x 10.5 | 19 x 27 | Underwear, scarves, kids tees | 2.5 mil |
| 9 x 12 | 23 x 30 | One folded shirt, shorts, leggings, A4 documents | 2.5 mil |
| 10 x 13 | 25 x 33 | Adult T-shirts, thin jeans, up to 5 folded shirts | 2.5 mil |
| 12 x 15.5 | 30 x 39 | S to L hoodies, sweaters, dresses, jeans | 2.5 to 3 mil |
| 14 x 17 | 36 x 43 | Sweatshirts, light jackets, 2 to 3 item orders | 2.5 to 3 mil |
| 14.5 x 19 | 37 x 48 | XL/XXL hoodies, coats, shoe boxes | 3 mil |
| 19 x 24 | 48 x 61 | Winter coats, boots in box, blankets | 3 to 4 mil |
| 24 x 24 and up | 61 x 61+ | Bulk textiles, duvets, oversized goods | 3 to 4 mil |
Poly Bubble Mailer Sizes
Bubble mailers use a numbered scale. Usable interior space runs about 0.5 to 1 inch smaller than the outer size.
| Number | Size (in) | Best for |
|---|---|---|
| #000 | 4 x 8 | Jewelry, small accessories |
| #00 | 5 x 10 | Cosmetics, phone accessories |
| #0 | 6 x 10 | Skincare, stationery |
| #1 | 7.25 x 12 | Chargers, small electronics |
| #2 | 8.5 x 12 | Paperbacks, small gift boxes |
| #3 | 8.5 x 14.5 | Hardcovers, boxed accessories |
| #4 | 9.5 x 14.5 | Tablets in case, padded documents |
| #5 | 10.5 x 16 | Electronics kits, gift sets |
| #6 | 12.5 x 19 | Handbags, slim shoe boxes |
| #7 | 14.25 x 20 | Laptop sleeves, bulkier fragile goods |
Best Poly Mailer Sizes for Clothes
Match the mailer to the folded garment, not the tag size. This table covers the best size poly mailers for clothes by item.
| Garment | Best size | 2 mil is enough |
|---|---|---|
| Socks, underwear | 6 x 9 or 7.5 x 10.5 | Fold in thirds |
| Leggings, shorts, kids tees | 9 x 12 | The standard poly mailer for shirts |
| Adult T-shirt (S to L) | 10 x 13 | |
| T-shirt XL+, or 2 to 3 tees | 12 x 15.5 | |
| Jeans (1 pair) | 12 x 15.5 | 10 x 13 for thin or kids denim |
| Dress | 10 x 13 or 12 x 15.5 | Size by fabric weight |
| Hoodie or sweatshirt (S to L) | 12 x 15.5 | 3 mil for zip-ups |
| Hoodie XL/XXL | 14.5 x 19 | |
| Light jacket | 12 x 15.5 or 14 x 17 | |
| Winter coat | 19 x 24 | 3 to 4 mil |
| Shoe box | 14.5 x 19 or 19 x 24 | The box adds structure |
Poly Mailer Thickness Guide
Mil measures film thickness. One mil equals 1/1000 of an inch. Thicker film resists punctures and seam splits.
| Thickness | Use it for |
|---|---|
| 1.5 to 2 mil | Flat, light items under 0.5 lb |
| 2.5 mil | Standard for T-shirts and most clothing |
| 3 to 3.5 mil | Denim, zippers, hardware, heavier garments |
| 4 to 6 mil | Packages over about 2 lb, sharp or irregular items |
USPS requires at least 2 mil for polybag loads up to 5 lb and 4 mil for 5 to 10 lb. Loads over 10 lb go in a box. DHL in Europe requires at least 80 microns, which is about 3.1 mil.
Poly Mailers vs FBA Poly Bags
A poly mailer is a shipping envelope. An FBA poly bag is prep packaging that goes inside a carton to Amazon. They follow different rules.
Amazon’s FBA poly bag requirements include:
- Minimum 1.5 mil film thickness
- Transparent film so the barcode scans through the bag
- A suffocation warning when the opening is 5 inches or wider
- No more than 3 inches of excess bag past the product on any side
For the best poly bag size for clothes going to FBA, pick the smallest bag that fits the folded garment within that 3-inch limit. Our FBA prep services team bags apparel to these specs before it ships.
Things to Consider When Calculating Poly Mailer Size
Beyond basic measurements, several factors influence which poly mailer dimensions work best for your operation:
Carrier Dimensional Weight Pricing
Carrier dimensional weight pricing penalizes oversized packages relative to actual weight. Choosing an oversized poly mailer can increase your shipping fees significantly. Understanding the DIM weight formula(length × width × height ÷ a carrier factor of 139 to 166) before finalising your mailer size helps you confirm whether your packaging choice will be billed on actual or dimensional weight.
Label and Barcode Placement
Label and barcode placement requires adequate flat space. Your shipping label and any additional barcodes need smooth, flat surfaces to scan properly. especially when using a shipping label generator to ensure scannable and compliant labels. The size of a very small poly mailers might not accommodate labels without creating scanning issues at sorting facilities.
Multiple Items per Order
Multiple items per order change your poly mailer sizing requirements. When customers order three shirts instead of one, you need larger mailers or must split shipments. Plan your bag sizes around typical order patterns from your analytics.
Branding and Inserts
Branding and inserts consume internal space. If you’re including brand materials or tissue paper, account for their space. A 10×13 poly mailer size works for a single t-shirt but may be too small with added items.
Poly Mailer Guidelines of Different Carriers (FedEx, DHL, UPS, USPS)
Poly Mailer Rules by Carrier
| Carrier | What matters for poly mailers |
|---|---|
| USPS | Accepts poly mailers on Ground Advantage and Priority Mail. 2 mil up to 5 lb, 4 mil for 5 to 10 lb. |
| UPS | Accepts poly mailers. The label must sit flat on the largest face. |
| FedEx | Accepts poly mailers on Ground and Home Delivery. Stay within size and weight limits. |
| DHL (Europe) | At least 80 microns thick, no black film, no handles. The label must be at least 10 x 15 cm. |
Advantages and Limitations of Poly Mailers
Advantages and Limitations of Poly Mailers
Advantages:
- Lower cost per unit than boxes, with minimal storage space
- Lightweight (1-2 oz vs. 8-16 oz for boxes), reducing shipping costs
- Weather resistant in rain or snow
- Flexible design conforms to products and prevents internal damage
- Professional appearance with custom branding opportunities
- Space-efficient, allowing more packages per shipment
Limitations:
- Standard poly mailers do not protect fragile items. Use bubble mailers or boxes for glass and electronics.
- No stacking strength or structural support
- May not suit luxury or premium brand positioning
- Environmental concerns—takes hundreds of years to decompose
- Typically single-use due to permanent adhesive strips
- Can become sticky in extreme heat or brittle in extreme cold
Choosing Your Core Sizes
Start with your top ten SKUs by volume. Fold each one as you pack it and run the formula. Most catalogs land on two or three sizes. Stock those, pack-test samples, and review the mix each season as your product line grows.
FAQ
What is the standard poly mailer size?
The 10 x 13 inch poly mailer is the most common standard size. It fits one adult T-shirt, a pair of thin jeans, or up to about five folded shirts. The 12 x 15.5 is the second most stocked size.
What size poly mailer do I need for a T-shirt?
Use a 10 x 13 poly mailer for one adult T-shirt in sizes S to L. Kids and slim-fit tees fit a 9 x 12. For XL and up, or two to three shirts, move to 12 x 15.5.
What size poly mailer fits a hoodie?
A 12 x 15.5 poly mailer fits most S to L hoodies folded flat. XL and XXL hoodies need a 14.5 x 19. Heavyweight or zip-up hoodies also ship better in the larger size with a 3 mil bag.
What size poly mailer for jeans?
One pair of standard jeans fits a 12 x 15.5 poly mailer. Thin or kids denim can go in a 10 x 13. Two or more pairs, or heavy raw denim, need a 14.5 x 19 at 3 mil.
What size poly mailer fits a shoe box?
Most standard shoe boxes fit a 14.5 x 19 poly mailer. Larger boxes, like men’s size 12 and up or boots, need a 19 x 24. The box gives structure and the mailer adds water resistance.
How thick should a poly mailer be for clothes?
Use 2.5 mil for most clothing. It is the industry standard for soft goods. Step up to 3 or 3.5 mil for denim, zippers, or heavier garments. Go to 4 mil or more for packages over about 2 lb.
What is the height of a 10 x 13 poly mailer?
The first number is the width and the second is the length. A 10 x 13 mailer is 10 inches across the opening. It is 13 inches tall, from the bottom seam to the flap line.
Are poly mailer sizes measured with the flap?
No. Listed poly mailer sizes exclude the adhesive flap. The flap usually adds 1.5 to 2 inches of material but folds over to seal. Size your product against the listed width and length only.
How do I measure a poly mailer for shipping?
Lay the mailer flat. Measure width seam to seam across the opening, then length from the bottom seam to the flap line. For postage, measure the filled package at its longest, widest, and thickest points.
Does USPS accept poly mailers?
Yes. USPS accepts poly mailers for Ground Advantage, Priority Mail, and Priority Mail Express. Use at least 2 mil for loads up to 5 lb and 4 mil for 5 to 10 lb.
Can I use poly mailers with recycling symbols in California after October 2026?
Not on new stock. From October 4, 2026, mailers made for California cannot carry chasing arrows. They also cannot say “recyclable” unless they meet SB 343 criteria. Most standard poly mailers do not qualify.
Danny is a Fulfillment Expert at AMZ Prep who has established himself as a leader in supply chain optimization. His proven methodologies have helped organizations reduce fulfillment errors by 95%, implement sustainable packaging programs, and build distribution networks that scale profitably.
Helpful reminder to allow extra space for sealing and labels.
Knowing standard sizes in advance helps with bulk ordering.
Good explanation of when to use flat versus bubble poly mailers.
A practical reference for anyone shipping lightweight products.
The sizing advice helps reduce shipping issues and returns.
I liked how the sizing tips help avoid overpacking or wasted space.
Simple, well-organized, and useful for packaging decisions.
The examples for apparel and soft goods were especially helpful.
The breakdown of common poly mailer dimensions is clear and practical.
This size guide makes it much easier to choose the right poly mailer for different products.