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Guide

Mailer boxes: a complete guide

Everything you need to know about choosing, designing, and printing mailer boxes that survive the shipping journey and look like a brand surface inside and out.

The Cent team

Mailer boxes are the most-ordered structure in our catalog. They ship flat to your fulfilment centre, lock together without tape, and give your team a clean printable surface on both the outside and inside of the box. For DTC brands, the inside print is the unbox surface — the moment your customer films and posts.

Choosing the right flute

B-flute (3 mm) is the everyday choice for products under 5 lb. E-flute (1.5 mm) is the lighter, smoother option for premium-feel mailers under 2 lb — better print fidelity, less bulk on the shelf. F-flute (0.8 mm) is for boutique cosmetics and small electronics where you want corrugated structure but at near-cardstock thinness.

ECT ratings explained

ECT (edge crush test) measures how much pressure the box edges can take before crushing. 32 ECT is the standard for general e-commerce shipping. 44 or 48 ECT is what you want for heavy products, fragile goods, or anything stacked in a freight environment.

Print and finish options

Mailers can be printed flexo (water-based, lower-fidelity, fast) or litho-laminated (full-color CMYK with photographic print quality). Flexo is the right call for one or two solid brand colors. Litho is for any design with photography, gradients, or fine detail.

MOQ and turnaround

We start at 50 units. Standard production runs 7 business days from approved artwork; 5 days with rush. The dieline and 3D mockup are free with every quote, and we keep your art on file so reorders ship in 5–7 days flat.

Field guides

More to read.

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