Poly Mailer Size Chart: Find the Right Size for Your Products (With CM & Inch Guide)
Choosing the right poly mailer size is one of the simplest ways to reduce shipping costs, speed up fulfillment, and improve the customer unboxing experience.
This guide includes a size chart, weight estimates, and a built-in calculator using the exact sizes offered by UNPAKFUL.
Introduction
Poly mailers are widely used for shipping apparel, textiles, and other non-fragile items. Using the wrong size, however, can lead to dimensional weight charges, stressed seams, or a poor first impression when the package arrives.
Below you’ll find practical sizing guidance, an official size chart, weight estimates, and a calculator to match your product dimensions to the best UNPAKFUL poly mailer size.
What Are Poly Mailers?
Poly mailers are lightweight shipping envelopes made from durable polyethylene film. They’re popular for eCommerce because they’re easy to store, quick to pack, and ideal for soft goods.
- Lightweight and cost-efficient
- Water-resistant and tear-resistant
- Easy to store and pack
- Ideal for soft, non-breakable items
Compared to cardboard boxes, poly mailers help many sellers reduce shipping costs—especially for apparel and textiles.
Why Choosing the Right Poly Mailer Size Matters
Selecting the correct poly mailer size impacts more than just fit:
- Lower shipping costs – Oversized packaging can increase dimensional weight
- Better protection – Less empty space means less shifting during transit
- Improved customer experience – A well-fitted package looks more intentional
The goal is simple: snug, not tight.
What Size Poly Mailer Should I Use? (Quick Answer)
The right poly mailer size depends on your product’s folded dimensions and thickness.
- T-shirts / shirts → 7.5″ × 10.5″ or 9″ × 12″
- Hoodies / pants → 12″ × 15″
- Sweaters / jeans → 15″ × 20″
- Jackets / bulky apparel → 18″ × 24″ or 20″ × 28″
Tip: Choose a mailer that’s 2–5 cm larger than your folded product size for easy packing.
UNPAKFUL Custom Poly Mailer Sizes (Official Chart)
These are the exact poly mailer sizes available from UNPAKFUL, shown in inches and centimeters with common use cases.
| Size (inches) | Size (cm) | Typical uses |
|---|---|---|
| 6″ × 9″ | 15.3 × 23 cm | Jewelry, socks, small accessories |
| 7.5″ × 10.5″ | 19 × 27 cm | Kids’ clothing, thin T-shirts |
| 9″ × 12″ | 23 × 30 cm | Adult T-shirts, folded tops |
| 12″ × 15″ | 30 × 38 cm | Hoodies, pants, multi-item orders |
| 15″ × 20″ | 38 × 52 cm | Sweaters, jeans, light jackets |
| 18″ × 24″ | 45 × 60 cm | Bulky apparel, winter clothing |
| 20″ × 28″ | 50 × 70 cm | Oversized garments, bulk shipments |
Poly Mailer Size Calculator (CM / IN Toggle)
Not sure which size to choose? Use this calculator to find the best UNPAKFUL poly mailer size based on your product dimensions. Switching units will automatically convert your numbers.
UNPAKFUL POLY MAILER SIZE CALCULATOR
ENTER YOUR PRODUCT’S FOLDED DIMENSIONS TO GET THE BEST UNPAKFUL POLY MAILER SIZE.
Poly Mailer Weight Guide (Estimated)
Knowing the weight of an empty poly mailer helps you estimate shipping costs more accurately. Below are typical weight estimates based on standard poly thickness (approximately 2.5–3 mil).
| Poly mailer size | Approx. weight |
|---|---|
| 6″ × 9″ | 6–8 g |
| 7.5″ × 10.5″ | 8–10 g |
| 9″ × 12″ | 10–14 g |
| 12″ × 15″ | 16–20 g |
| 15″ × 20″ | 24–30 g |
| 18″ × 24″ | 35–45 g |
| 20″ × 28″ | 50–65 g |
Note: Actual weight may vary depending on material thickness and printing, but poly mailers are significantly lighter than boxes—making them ideal for eCommerce shipping.
How to Calculate the Right Poly Mailer Size
To choose the correct poly mailer size:
- Measure your product’s folded length, width, and thickness
- Add the product thickness to both width and length
- Add extra space for easy insertion
Simple sizing formula
- Mailer width = product width + product thickness + 2–3 cm
- Mailer length = product length + product thickness + 4–5 cm
This method ensures a secure fit while minimizing wasted space and shipping cost.
Poly Mailers vs. Boxes: Cost Advantage
For apparel and soft goods, poly mailers are often more cost-effective than boxes because they:
- Avoid dimensional weight pricing
- Reduce material and storage costs
- Speed up packing and fulfillment
In many cases, eCommerce sellers can reduce shipping costs by 30–60% when switching from boxes to properly sized poly mailers.
Why Use Custom Poly Mailers?
Beyond size and weight, custom printed poly mailers add branding value to every shipment. They help you reinforce brand identity at delivery, create a memorable unboxing experience, and look more professional than plain packaging.
UNPAKFUL custom poly mailers are available in multiple practical sizes and fully customizable with your branding—designed specifically for modern eCommerce shipping.
Final Tips for eCommerce Sellers
- Stock 2–3 core sizes instead of too many
- Size up for thicker or seasonal apparel
- Match packaging size with your best-selling SKUs
- Use branded mailers to stand out at delivery
Conclusion
Choosing the right poly mailer size is a small decision that makes a big impact on shipping costs, efficiency, and customer experience. By selecting the correct size—and using custom branded mailers—you can ship smarter, faster, and more professionally.
View the full range of sizes from UNPAKFUL here:
https://unpakful.com/products/custom-poly-mailers
FAQ
What size poly mailer should I use for shipping?
The right size depends on your product’s folded dimensions and thickness. T-shirts typically fit 7.5″ × 10.5″ or 9″ × 12″, hoodies fit 12″ × 15″, and bulkier apparel works best with 15″ × 20″ or larger sizes.
How do I calculate the correct poly mailer size?
Measure folded length, width, and thickness. Add thickness to both width and length, then add 2–5 cm for easy packing.
How much does an empty poly mailer weigh?
Typically 6 g to 65 g depending on size. Smaller 6″ × 9″ mailers are about 6–8 g, while 20″ × 28″ mailers are about 50–65 g.
