What box for A3 documents and prints? Inside sizes and dim weight

A3 documents and prints measure 11.69 × 16.54 in (297 × 420 mm). With 1 in of cushioning on every side, a 1 in stack needs a box at least 18.54 × 13.69 × 3 in inside; a shallow die-cut mailer or a telescope box suits flat goods better than a deep slotted carton.

Inside sizes by stack thickness and cushioning

Stack, inCushion per sideInside box, inSuggested styleSmallest library size that fitsUSPS DWFedEx DW
0.50.517.54 × 12.69 × 1.5042718 × 18 × 6n/a4 lb
0.5118.54 × 13.69 × 2.5042720 × 14 × 10n/a6 lb
0.5220.54 × 15.69 × 4.5042722 × 16 × 1213 lb13 lb
10.517.54 × 12.69 × 2042718 × 18 × 6n/a4 lb
1118.54 × 13.69 × 3042720 × 14 × 10n/a6 lb
1220.54 × 15.69 × 5042722 × 16 × 1216 lb13 lb
20.517.54 × 12.69 × 3042718 × 18 × 6n/a6 lb
2118.54 × 13.69 × 4042720 × 14 × 10n/a8 lb
2220.54 × 15.69 × 6042722 × 16 × 1218 lb15 lb
40.517.54 × 12.69 × 5042718 × 18 × 6n/a9 lb
4118.54 × 13.69 × 6042720 × 14 × 1015 lb12 lb
4220.54 × 15.69 × 8030122 × 16 × 1224 lb20 lb

Inside = item + 2 × cushion on each axis. Dimensional weight uses C flute outside dimensions (ID + 2 calipers on L and W, + 3 on depth); n/a means USPS bills actual weight below 1,728 in³. Divisors checked 2026-10-27. The suggested style is a rule of thumb: 0427 for depths to 6 in, 0301 beyond.

Packing notes

  • Keep flat goods flat: a box whose depth is far more than the stack invites shifting, so fill or reduce the depth.
  • Corners take the knocks; corner protectors or a rigid pad on each face protect edges better than loose fill.
  • Large sheets (16.54 in long side) fit common flat mailers without rolling.

Open this item in the Spec Builder to set your own thickness, weight and carriers.

Other formats

Sources