A literature mailer carries printed matter flat: catalogs, lookbooks, press kits, manuals, certificates. That makes it one of the few boxes where the correct internal size can be calculated rather than guessed, because the sheet sizes are published standards. Start with the paper, add clearance, then decide the board.
Work from the published sheet size
The figures below are arithmetic: a standard sheet size plus a normal clearance allowance. They are industry-typical starting points for the conversation, not stock sizes held on a shelf. Your real internal size depends on how thick your stack is and whether anything rides with it.
| What the mailer carries | Published sheet size | Internal length x width starting point |
|---|---|---|
| US letter, flat | 8.5 x 11 in | About 9 x 11.5 in |
| US letter, folded in half | 5.5 x 8.5 in folded | About 6 x 9 in |
| US legal, flat | 8.5 x 14 in | About 9 x 14.5 in |
| ISO A4, flat | 210 x 297 mm | About 222 x 310 mm |
| ISO A5, flat | 148 x 210 mm | About 158 x 222 mm |
The third number is the one people forget
Length and width come from the paper. Depth comes from the stack, and it is where most first orders go wrong. Measure the finished, bound, shrink wrapped stack with a caliper or a ruler against a flat edge, not the page count. A saddle stitched catalog is thicker at the spine than at the face, so measure at the spine. Perfect bound pieces measure honestly. If a sample, a card or a foam pad rides along, measure the assembled contents as one block.
Then decide how snug you want it. A mailer that grips the contents needs almost no void fill, but it is unforgiving if your printer runs a heavier stock next time. A mailer with 1/4 in of slack on each side ships quietly and takes a reprint at a different caliper without a new die. Say which of the two you want on your quote, because it changes the dieline.
Internal or external, state it once
Quote every dimension as internal, in length x width x depth order, and say so in writing. Corrugated board adds real thickness to the outside: E flute is about 1/16 in and B flute about 1/8 in per wall, which is enough to push a mailer past a carrier dimension band if someone assumed your numbers were external. Our proofs and dielines state internal dimensions, and we confirm the interpretation before the die is cut. If you have a competitor's box in hand and want to match it, measure its inside, not its outside.
Board, print and how it gets ordered
Most literature mailers run on E flute corrugated for a printable surface with enough stiffness to resist the bend that snaps a spine, or on a heavier paperboard when the piece is light and the look is the point. Kraft and white board both print well, and materials on offer include kraft, standard white cardstock, corrugated stock, rigid press board and textured stock.
The minimum is 100 boxes. Pricing starts from about $0.48 per unit at bulk volumes and is confirmed on a written quote, never guessed from a chart. The die, the plates, design support, US shipping and a digital proof before anything prints are included. Turnaround is quoted per job across three lanes, rush (expedited production plus air freight), standard (air) and cost saver (sea), from about 7 business days, plus 2 to 5 for delivery. Rush carries a premium of about 7 to 25% depending on the job.
If you have the sheet size and the measured stack thickness, that is enough to quote. Send both on the quote form and we will come back with the internal dieline and the lane options. For neighbouring formats, see literature box dimensions or mailer box dimensions.
