Last updated: March 2026
Enter your item dimensions and box size to check the fit — shipping boxes, moving boxes, and storage containers.
Whether it fits depends on measurements most people get wrong.
Item dimensions + padding allowance vs. box interior dimensions
Item: Varies — measure your item including any padding needed
Space: Medium box: ~14" × 14" × 14" interior. Large: ~18" × 18" × 18" interior
Actual clear openings are usually 1–2″ smaller than the labeled size.
Your exact dimensions probably aren't "standard." Small measurement errors cause big problems — 1 inch can be the difference between fitting and getting stuck.
Verdicts are calculated by comparing all 6 item orientations against the space dimensions using verified building code standards. See our methodology
Takes 10 seconds · No signup needed
1 inch can be the difference between fitting and getting stuck.
“Checked my carry-on against 3 airlines before a trip. Saved me a gate-check fee.” — Frequent flyer
Measurements verified by the ItemFits engineering team · Our methodology
Standard sizes say it works — but your measurements are what matter.
Install the free ItemFits extension — it reads product dimensions on IKEA, Wayfair, Amazon and tells you if it fits before you buy.
Small: 8" × 6" × 4". Medium: 14" × 14" × 14". Large: 18" × 18" × 18". Extra large: 24" × 18" × 18". USPS flat rate: Small (8.6" × 5.4" × 1.6"), Medium (11" × 8.5" × 5.5"), Large (12" × 12" × 5.5").
For fragile items, add 2–3 inches of padding (bubble wrap, foam) on all six sides. For sturdy items, 1 inch of crumpled paper is sufficient. The item should not be able to move when you shake the sealed box.
USPS: 108" max length, 130" max length + girth. UPS/FedEx: 108" max length, 165" max length + girth. Oversize packages incur surcharges. Girth = 2 × (width + height).