How to Calculate Box Girth for USPS

Is your business preparing to ship an odd-sized parcel, such as a piece of used machinery, or are you mailing a large box of wholesale merchandise to a key client? In either case, you will need to measure the package to determine the shipping options available to your business. Box girth is a key measurement when determining shipping charges. The sum of length plus girth will also dictate the appropriate shipping categories for a package via the U.S. Postal Service (USPS).

Start by identifying the longest side of your package. The side perpendicular to the longest side is then measured for girth. If geometry isn't your forte, picture a box as a skyscraper. The outer tall edge of the building is your long side. The girth measurement is the perimeter (the sum of all four sides) of the base of the ground floor or top floor.

The USPS imposes maximum sizes for packages. For standard shipments, the combined measurement of the longest side and the girth cannot exceed 108 inches. By paying a nonmachinable surcharge on the parcel, you can increase the size to a total of 130 inches in combined length and girth. Keep in mind that many larger parcels are also heavier, and weight limits are also imposed. The maximum weight for a standard parcel is 25 pounds and 35 pounds for a nonmachinable parcel. If your business is books, however, the media mail parcel class allows the shipment weight up to 70 pounds.

Did your box just miss the mark with the postal service? Both UPS and FedEx determine package size with the same length plus girth measurement system and accept larger packages. UPS carries packages up to 108 inches in length and 165 inches in combined length plus girth. FedEx handles packages up to the same maximum size, and both companies enforce a maximum weight of 150 pounds. A parcel that exceeds any of these measurements would need to be transported via a freight shipping company.

If your package meets USPS shipping requirements, you can use Click-N-Ship to buy postage or take the package to any local post office for mailing. After opening Click-N-Ship, enter your ZIP code and the package's destination ZIP code. Click-N-Ship will then ask about the shape of your box and tell you to input the dimensions and weight of the package. All available shipping options are displayed, as well as the cost of postage. You can then choose to purchase postage and print a shipping label.