What is LDPE?
LDPE stands for Low-Density Polyethylene. It's one of the most common plastics used in packaging — you've seen it before on food bags, squeeze bottles, and yes, courier mailers. It's flexible, lightweight, and surprisingly tough for how thin it is.
But not all LDPE is the same. The number that matters is the thickness, measured in micrometers (μm). A micrometer is one-thousandth of a millimetre — so when we say 55μm, we mean the material is 0.055mm thick.
So why 55μm specifically?
It's a sweet spot. Here's what that means in practice:
Thinner than 55μm (e.g. 25–40μm) — cheaper, but tears more easily. Fine for lightweight items in controlled environments, not great for real-world courier logistics where packages get thrown, stacked, and dragged.
Around 55μm — strong enough to survive the sorting machines and rough handling at courier facilities, flexible enough to fold around your product without cracking, and light enough that it doesn't add meaningful weight to your shipment.
Thicker than 55μm (e.g. 80–100μm) — very durable, but you're paying more per unit and the extra thickness isn't doing much extra work for most e-commerce shipments.
For the vast majority of online sellers shipping small-to-medium items, 55μm is the standard that balances cost, durability, and weight.
Why does thickness matter for e-commerce?
When your package travels from your door to your customer's door, it doesn't go in a straight line. It gets scanned, sorted, stacked on top of other packages, loaded into vans, and sometimes dropped. A mailer that's too thin will split open somewhere along that journey. A mailer at 55μm is built to handle all of that without failing.
What about the environment?
LDPE is recyclable — it's plastic recycling code 4. And when it's made from post-consumer recycled material (like our mailers are), you're reducing the demand for virgin plastic. That's a real difference, not just a marketing claim.