Shipping Box Size Calculator 2026: USPS, UPS, FedEx Limits

Calculate packed box dimensions, USPS cubic eligibility, carrier size limits, DIM-weight handoff risk, and source-backed box-fit notes before listing.

Item length

Item width

Item height

Packed weight

Padding per side

Package shape

Decision

USPS cubic candidate

Copy the packed dimensions into your label flow and compare USPS, UPS, and FedEx before buying stock boxes.

14" x 10" x 6"

packed box

Cubic feet

0.486

L + girth

46.0"

USPS Ground Advantage

Fits

Limit checked: 70 lb and 130 inches length plus girth. USPS says 108-130 inches can be oversized.

GA cubic: 0.50 cubic

UPS parcel

Fits

Limit checked: 150 lb, 108 inches max length, and 165 inches length plus girth.

UPS rounds package dimensions up for measurement.

FedEx Ground

Fits

Limit checked: 150 lb, 108 inches max length, and 165 inches length plus girth.

Run the final rate quote before offering free shipping.

Plain stock boxes that fit

Plain 14 x 10 x 6 box

Plain own box - 14" x 10" x 6"

840 in3

Sneakers, camera kits, plush with compression.

Plain 18 x 14 x 6 box

Plain own box - 18" x 14" x 6"

1512 in3

Flat art, board games, framed items.

Plain 16 x 12 x 8 box

Plain own box - 16" x 12" x 8"

1536 in3

Bulkier electronics, handbags, small appliances.

Plain 24 x 18 x 6 box

Plain own box - 24" x 18" x 6"

2592 in3

Posters, flat decor, long clothing lots.

USPS-provided boxes that fit

No USPS-provided box in the checked list fits. Use own packaging or another carrier quote.

DIM weight handoff

If the packed box is over 1 cubic foot, longer than 22 inches, or close to a marketplace free-shipping promise, run the exact external box through DIM weight before listing.

Open DIM calculator