Ordering the wrong poly mailer size is the most common (and most expensive) mistake new clothing sellers make. Too small and items do not fit without forcing; too large and you are paying for wasted material. Here is the definitive 2026 size guide.
The Universal Poly Mailer Size Chart for Clothing
| Clothing Item | Recommended Size | Notes |
|---|---|---|
| T-shirts (S–L), folded | 9×12” or 10×13” | 10×13 preferred — more breathing room |
| T-shirts (XL–XXL), folded | 10×13” | Standard choice for most clothing sellers |
| Jeans / Pants, folded | 10×13” or 12×15.5” | 12×15.5 for plus sizes |
| Dresses (casual) | 10×13” or 12×15.5” | Depends on fabric weight |
| Dresses (formal / heavy) | 12×15.5” or 14.5×19” | Heavier fabrics need more room |
| Hoodies / Sweatshirts | 12×15.5” or 14.5×19” | Thick materials compress but need space |
| Light jackets | 12×15.5” | Roll tightly before sealing |
| Socks (1–2 pairs) | 6×9” | Perfect for small accessories too |
| Scarves / Bandanas | 9×12” | |
| Leggings / Yoga pants | 10×13” | |
| Swimwear | 9×12” or 10×13” | Lightweight, compresses well |
| Multi-item lots (2–3 garments) | 14.5×19” or 19×24” | Bundle shipments need larger sizes |
The Golden Rule: Size Up, Not Down
When you are between two sizes, always choose the larger one. A mailer that is slightly too large wastes a few cents of material. A mailer that is too small causes: (a) difficulty sealing, (b) the seal failing in transit, (c) items arriving partially open, and (d) buyer complaints. The cost asymmetry is extreme — always size up.
What Most Sellers Get Wrong About Poly Mailer Sizing
Mistake 1: Measuring the item flat, not folded. The size of your item flat is not what matters. What matters is the size after you fold and compress it for packing. A large t-shirt might be 24” wide unfolded but folds down to 9”x10” easily.
Mistake 2: Forgetting that some USPS machines scan barcodes on both sides. If your poly mailer is too full and puffs out, automated scanners can miss the barcode. Keep your mailer below 1” of puff depth to ensure reliable scanning.
Mistake 3: Ordering only one size. If you sell clothing across multiple categories, stock two sizes: a 10×13 for your everyday single-item shipments, and a 12×15.5 or 14.5×19 for heavier or multi-item orders. Having only one size leads to forcing items or wasting oversized mailers.
How to Fold Clothes for Maximum Poly Mailer Efficiency
Military-style rolling beats folding for most garments — especially for t-shirts and leggings. Roll from bottom to top, compressing as you go. A military-rolled t-shirt takes up 40% less space than a traditionally folded one, letting you use a smaller (cheaper, lighter) mailer.
For jeans: fold in half lengthwise, then tri-fold from the bottom. This creates a compact rectangle that fits easily in a 10×13 for most sizes.
Starter Pack for New Clothing Sellers
If you are just starting out selling clothing on eBay, Etsy, or Amazon:
- 50× 10×13” poly mailers (your main size)
- 25× 12×15.5” poly mailers (for bulkier items)
- A roll of packing tape
That covers roughly 95% of all clothing shipments. No need for anything else until you understand your product mix better. Browse poly mailers at SenderNest — no order minimums, all sizes available, ships same day.