How To Measure A Box For Usps. Measure the three parcel dimensions in inches: 50 inches (length) x 40 inches (width) x 30 inches (height).
The width is generally a smaller number than the length. Pack your box to protect your contents and to make sure the box arrives intact. When shipping with usps, packages must meet weight and size limits.
Start by identifying the longest side of your package.
The smallest box has a minimum length of 6 inches and a minimum height of 4 inches. 40 inches (width) + 30 inches (height) = 70 inches. So your package is 24 x 18 x 12. 70 inches x 2 = 140 inches (girth).