Enter your item dimensions and the calculator recommends the smallest standard box that fits, with room for packing material.
“Checked my carry-on against 3 airlines before a trip. Saved me a gate-check fee.” — Frequent flyer
Measure smart
Four numbers decide nearly every fit check. Get these right and the rest follows.
Don't make these
Most “it didn't fit” stories trace back to one of these oversights.
Frequently asked
Add 2 inches on each side of the item (4" total per dimension). This provides room for bubble wrap, packing paper, or foam. A 10×10×10" item needs a 14×14×14" box.
01Common sizes: Small (12×10×6"), Medium (18×14×12"), Large (24×18×18"), Extra Large (24×20×24"). Most carriers also accept custom sizes up to 165" combined length + girth.
02Measure the item at its widest points, add 2 in on every side for padding, and round up to the next standard box. A 10 x 10 x 10 in item needs a 14 x 14 x 14 in box. For a long rigid item, size to the longest dimension first, because that is the one that decides the box.
03Take the item length, width and height at the widest points and add 4 in to each, which is 2 in of padding per side. Then pick the smallest standard box that meets or exceeds all three numbers, and check it against the carrier limit of 165 in for combined length plus girth.
04Usually yes, because carriers price on dimensional weight as well as actual weight. Dimensional weight is length times width times height divided by a carrier divisor, commonly 139 for domestic air, so an oversized lightweight box is billed as though it were heavy. Dropping one standard box size often saves more than the extra packing material costs.
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