Home › Blog › 2.5 vs. 3.5 Mil Poly Mailers: Which Thickness Do You Need?

2.5 vs. 3.5 Mil Poly Mailers: Which Thickness Do You Need?

04/01/2026

Mil thickness — a measure of film gauge, where one mil equals one thousandth of an inch — is the single spec that most affects how a poly mailer performs and what it costs. Most of our customers ask about it once, so here’s the short version.

The two thicknesses we run most often are 2.5 mil and 3.5 mil. Both are coextruded, tear-resistant, and water-resistant; the difference is in margin for error.

2.5 mil: the standard choice for soft goods

A 2.5 mil mailer is our Standard Poly Mailer’s base film — light, flexible, and plenty strong for folded apparel, soft goods, and anything that isn’t sharp-edged or heavy. It costs less per unit and is the right default unless you have a specific reason to go heavier.

3.5 mil: added margin for weight and rough handling

A 3.5 mil mailer resists puncture and abrasion noticeably better, which matters for heavier multi-item orders, jumbo formats carrying real weight, or bubble-lined mailers where the added film needs to support a laminated lining without weak points.

Choosing for your order

If you’re shipping folded clothing, books, or small accessories under about two pounds, 2.5 mil is the economical, reliable choice. If your typical order runs heavier, includes multiple items, or you’ve had past issues with mailers splitting in transit, step up to 3.5 mil — the cost difference per unit is small relative to the reduction in damage claims.

Not sure which thickness fits your product? Get a custom quote and we’ll recommend one — free mockups in 24–48 hours. Learn more about how we work, or browse more guides.

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Home › Blog › Custom Poly Mailers for E-commerce & DTC Brands: A Launch Guide

Custom Poly Mailers for E-commerce & DTC Brands: A Launch Guide

03/15/2026

Most e-commerce and DTC brands ship their first hundred orders in plain, unbranded mailers because it’s the fastest way to get moving. But the outbound package is one of the few brand touchpoints a customer experiences in physical space, and switching to a custom-printed poly mailer is one of the cheapest upgrades available — often adding just a few cents per unit over an unbranded mailer.

Here is how to plan your first branded poly mailer launch without overthinking it.

Step 1: Pick your primary size

Look at your last 90 days of orders and identify the size that covers the largest share of shipments — usually a mid-size mailer in the 10×13 in to 12.5×15.5 in range for apparel and general DTC goods. Standardize on that size first; you can add a second size later for outliers.

Step 2: Decide on print placement

Outside print gets maximum visibility on a porch or loading dock. Inside print keeps the exterior plain, which some brands prefer for security or to blend into a 3PL’s general packaging flow. Most DTC brands choose outside print for the marketing value.

Step 3: Set your first order quantity

Ordering closer to your actual monthly volume keeps unit cost down without tying up cash in six months of inventory.

Step 4: Build in lead time

Standard production runs about two weeks from mockup approval. Plan your first order at least three weeks ahead of any launch date to leave room for design revisions and shipping.

Choosing for your launch

Start with one primary size, outside print, and a quantity sized to about one to two months of volume. Once you see how the mailer performs — unboxing photos, social shares, return rates — you can branch into a second size or a bubble-lined version for fragile SKUs.

Ready to launch your branded mailer program? Get a custom quote — free mockups in 24–48 hours. Learn more about how we work, or browse more guides.

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