What is a Poly Mailer? Learn More About the Many Benefits and Uses.

In the world of e-commerce, packaging is more than just a vessel—it’s a critical factor in your bottom line and your customer’s first impression. Enter the poly mailer: a lightweight, moisture-resistant, and incredibly versatile shipping envelope that has become the gold standard for modern fulfillment. Made from durable polyethylene, these sleek mailers offer a high-performance alternative to bulky corrugated boxes, providing a secure shield against dirt and tampering while significantly slashing your shipping costs. Whether you're sending out the latest apparel trends or soft goods, poly mailers are the secret weapon for merchants looking to ship smarter, faster, and more affordably.

In this piece, we’ll explore the nitty-gritty behind what poly mailers actually are, various uses, and how they can help e-commerce companies ship merchandise easily, effectively, and on the cheap. 

What Are Poly Mailers Made of?

Poly mailers are made of polyethylene—a light, synthetic resin that composes the most widely-used plastic in the world. Polyethylene is used to produce everything from shopping bags to clear food wrapping, detergent bottles, and even automobile fuel tanks. 

Small Footprint, Big Savings: The Poly Mailer Edge

Switching from traditional boxes to poly mailers is one of the easiest ways to instantly lower your overhead. Because they are ultra-thin and lightweight, poly mailers keep your package’s dimensional (DIM) weight to a minimum, often allowing you to qualify for lower shipping tiers that boxes simply can’t reach. This efficiency extends beyond postage; poly mailers require far less storage space in your warehouse or home office, freeing up valuable square footage for more inventory.

Beyond cost-cutting, poly mailers offer a unique canvas for brand storytelling. Unlike plain brown cardboard, these mailers can be easily customized with vibrant colors, logos, and unique finishes that turn a standard delivery into a "unboxing" experience. By choosing the right variety—such as eco-friendly recycled options or extra-protective bubble-lined mailers—you can align your shipping strategy with your brand values, ensuring your products arrive safely while making a lasting impact on your customers.

Poly Mailer Varieties

There’s no one-size-fits-all shipping solution with poly mailers. In fact, there are many different types to choose from: 

Layflat Poly Mailers

Layflat poly mailer bags are basically the industry standard. If you’ve ever ordered something from a popular e-commerce company, you’ve probably received it in a layflat poly mailer. It’s a flat plastic bag that can hold a wide array of items, is good for items that don’t need a lot of cushioning, and can be easily affixed with stamps and sealed with a self-adhesive strip. 

Clear View Poly Mailers 

Clear view poly mailers are a solid choice for shipping print materials like catalogs, brochures, and magazines. They’re completely transparent (hence the clear view) on one side with an opaque backside that’s perfect for postage, labels, and other shipping information. 

Bubble-Lined Poly Mailers

For fragile goods that don’t necessarily need a fully packaged box, bubble-lined poly mailers offer extra cushioning and added protection. They’re a low-cost way to send small, delicate items to customers and are usually self-sealable. 

Expansion Poly Mailers

Expansion poly mailers come with an expandable, durable seam along the side that makes it easier and more efficient to ship bulky items. These work well for shipping large items like jackets, sweatshirts, books or binders. 

Returnable Poly Mailers

As we all know, product returns are one of the many inherent costs of doing business online. Returnable poly mailers are a popular way to ship products while planning ahead for potential returns (and are often included in initial shipments). They have two self-seal adhesive closures, offering customers the ability to conveniently return an order directly to your receiving address.

Recycled Poly Mailers 

If you’re trying to build a more eco-friendly, sustainable business, 100% recycled poly mailer bags are made with a mixture of post-industrial and post-consumer materials and have a significantly lower carbon footprint than their virgin counterparts. 

A Cost-Effective Shipping Option

One of the biggest advantages of poly mailers is their affordability, for both purchasing and shipping. For instance, poly mailers can be shipped via USPS First Class Mail, for lightweight packages (under 13 oz), starting at just $0.49. (Try out our USPS postage calculator for an idea of actual discounted rates when using Shippo.) In terms of purchasing, when buying in bulk, poly mailers ring in at around $0.25 per unit, while mailer boxes of a similar size can cost upwards of $1.25 each.

Made for Easy Storage

Spatial relationships don’t have to be your strong suit to see why shipping boxes—even if they’re collapsed—take up more space than poly mailer bags. Cardboard can create a lot of clutter in the packaging process, turning your fulfillment area into a bit of a… hazard zone. Poly mailers, on the other hand, are simple to lay out and pack products into and they don’t require the abundance of assembly that comes with corrugated cardboard boxes. 

Designed for Durability

Weather-proof, water/dust resistant and not easily torn, poly mailers are able to withstand a wide range of conditions without compromising the contents inside. 

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Optimal Uses for Poly Mailers

Poly mailers are nothing if not versatile and they work well for fabric-based goods like clothing and textiles. Certain types of hats and shoes ship easily in poly mailers, too. And boxed products that need an added layer of protection like jewelry boxes, shoe boxes, and small toys also travel well in poly mailer bags. 

The important things to consider when shipping with poly mailers is whether the items are fragile (in which case, a bubble-lined poly mailer or corrugated box with padding or void fill might be better) and whether they will fit in a small, medium or large-sized mailer. 

For reference, here’s a little breakdown of sample goods paired with poly mailers of each size: 

Small Poly Mailer (7.5×10.5”)

Could ship soft goods like:

Could ship small boxed goods like:

Medium Poly Mailer (10×13”)

Could ship soft goods like:

Could ship medium boxed goods like:

Large Poly Mailer (14.5×19”)

Could ship soft goods like:

Could ship large boxed goods like:

Ways Not to Use Poly Mailers

As versatile as they are, there are certain scenarios where a poly mailer simply won’t cut it for shipping: 

The Contents are Fragile

Products that are breakable or easy-to-damage (fragile or delicate materials, glass, etc.) shouldn’t be shipped in a standard poly mailer but might work in a bubble-lined or padded poly mailer. 

There’s More Than One Item Being Shipped

Unless it’s something like soft apparel, poly mailers aren’t necessarily the best packaging solution when you’re shipping several items at once. A box with air padding is typically a better option, particularly if the items are fragile. 

The Product Doesn’t Properly Fit in the Poly Mailer 

While it might seem easy enough to slip an item into whichever poly mailer you have on hand, poorly filled poly mailers can actually cause confusion during the sorting process for major carriers and USPS alike. Flat spots or gaps can be misread by scanning mechanisms that might lead to shipping errors, damages, delays, or even the dreaded Return to Sender. 

Opting for a stiffer packaging solution like padded mailers, rigid mailers or corrugated cardboard boxes could be your best bet for products that fit poorly in a poly mailer. 

Can Poly Mailers Be Customized?

Customized packaging has been a growing trend in the e-commerce industry for the last few years and it doesn’t appear to be going anywhere anytime soon. And according to the Paper and Packaging Board, a whopping 72% of consumers agree that packaging design can influence their purchasing decision. 

This gives growing merchants a serious opportunity to flex their customization muscles and show customers why buying from them is one of the best decisions out there. 

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Poly mailers are easy to customize and can help reinforce brand loyalty and keep customers coming back for more. Here are a few ways to do just that:

Shippo Can Help