Choosing the right mailer box size affects shipping cost, product protection, and unboxing experience. This guide covers standard dimensions, material options, and sizing strategy.

Mailer boxes are the workhorse of e-commerce packaging. Getting the size right means lower shipping costs, better product protection, and a cleaner unboxing experience. Here is what you need to know.

Standard Mailer Box Sizes

Common mailer box dimensions (inner length × width × height):

  • Small: 200×150×50mm — ideal for jewelry, small accessories, cosmetics samples
  • Medium: 250×180×80mm — suitable for apparel, books, beauty product sets
  • Large: 320×240×100mm — fits shoes, electronics, multi-item orders
  • Extra Large: 400×320×120mm — for bulk orders, gift sets, oversized items

Corrugated Flute Types

The corrugated layer determines the box's protective performance. E-flute (1.0–1.5mm) is the most common for mailer boxes — it provides good cushioning while keeping the box compact. B-flute (2.5–3.0mm) is thicker and more rigid, suitable for heavier items. For fragile products, consider double-wall (EB-flute) construction.

Sizing Strategy

Leave 5–10mm of clearance around the product on each side. Too tight and the product may be damaged during insertion; too loose and the product shifts during transit. Use inserts — pulp trays, corrugated dividers, or paperboard platforms — to fill excess space and hold the product firmly.

Shipping Cost Impact

Carriers charge by dimensional weight, not just actual weight. A box that is 20% larger than necessary can increase shipping cost by 15–30%. If your product ships in volume, even a 10mm reduction in box height can generate significant annual savings.

Branding on Mailer Boxes

The inside of a mailer box is prime real estate. A single-color logo print on the inside lid costs very little but significantly improves the unboxing experience. For outside printing, flexographic printing is cost-effective for 1-2 colors; lithographic lamination is better for full-color designs but requires higher MOQ (typically 1000+ units).