Poly Mailer Thickness Explained: What Mil Rating You Actually Need
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"Mil" is a thousandth of an inch — a 2.5 mil mailer is 0.0025" of co-extruded film. It's the spec that decides whether your mailer survives the sort line, and it's where cheap suppliers quietly cut.
The practical ladder
| Thickness | Behavior | Use it for |
|---|---|---|
| 1.6 – 2.0 mil | Light, tears at stress points under load | Ultra-light contents, inner bagging |
| 2.5 mil | The e-commerce standard — puncture-resistant through national parcel networks | Apparel and general soft goods |
| 3.0+ mil | Heavy film for sharp or dense contents | Hardware, mixed heavy orders, rough export lanes |
Why co-extrusion matters
Good mailers are multi-layer films — typically a white outer layer for print and scan contrast over a dark inner layer for opacity and strength. Single-layer film at the same mil rating tears sooner and shows contents against light. If a price looks too good, this is usually why.
Three tests you can run at your desk
- Punch test: push a pen cap into the bag face — quality film stretches and resists before it gives.
- Seam pull: load with a couple pounds of product and yank the side seams. Seams should outlast the film.
- Seal check: close the lip, wait, and try to peel it. A permanent seal that lifts clean at the desk lifts clean in transit.
This is exactly what the sample kit is for — run these tests on our film against whatever you're using now. We manufacture our poly mailers on our own lines, so the spec on the line sheet is the spec on the pallet.
FAQ
What does mil mean for poly mailers? One mil is a thousandth of an inch of film thickness — a 2.5 mil mailer is thicker and more tear-resistant than a 2.0 mil one.
What thickness poly mailer should I use? 2.5 mil covers most apparel and soft goods; drop to 2.0 mil for light single-item orders and step up for sharp or heavy contents.
Do thicker mailers cost more to ship? The film-weight difference is grams — carrier cost rarely changes. Thickness is about protection, not postage.
Buying at volume?
Our wholesale line sheet publishes per-unit pricing by pallet tier — no quote request needed to see numbers. Want to touch the product first? The $29 sample kit covers six product lines and is credited in full against your first wholesale order.
See the line sheetOrder the $29 sample kit
Questions? Call (619) 703-0245 — we manufacture our poly & bubble mailers in Tijuana and ship from U.S. inventory.