Compare the dimensional weight above with the actual package weight and use the heavier number to determine shipping cost
*Fractions are rounded to the next whole pound.
Dimensional weight reflects the amount of space a package occupies in relation to its actual weight. Think about the available space in a truck or plane – if your package is taking up a bit more space than the weight the package captures in rates, you will pay for that space.
Often referred to as “Dim weight”, pricing is based on volume versus actual weight of shipments. It is calculated by determining the cubic size of a package — multiplying its length by width by height and dividing by 139 (U.S. domestic services packages less than or equal to 1,728 cubic inches will continue to use a 166 divisor). The merchant will be charged the greater of the Dim weight or the actual, scale based weight.
Dim weight is the weight of a package based on its size rather than "actual weight". UPS and FedEx calculate a dim weight for their services and charge the greater of actual scale weight or dim weight to price packages.
To calculate, you will first determine the package dimensions in inches. For each package dimension, measure at the longest point, rounding each measurement to the nearest whole number (for example, 9.00 to 9.49 will be considered 9, and 9.50 to 9.99 will be considered 10).
Then, multiply the package length by the width by the height and divide by 139 for UPS and FedEx. The result is the dimensional weight. For those services where dimensional weight is relevant, take the greater of this calculation or the actual, scale based weight to determine the shipping cost.
USPS applies DIM domestically, but the divisor is 194 and only applies to Priority Mail® parcels larger than a cubic foot and going to zones 5-9.
All the time for UPS and FedEx services. USPS also applies dimensional weight to some packages (eg Priority Mail packages that exceed 1 cubic foot addressed to Zone 5 or above). So, best practice is to always enter package dimensions to make sure you're getting the best rate possible.
Changes for UPS went into effect on January 8, 2017. The same changes for FedEx went into effect on January 2, 2017. USPS did not change their Dim calculation for 2017.
You'll be paying the higher price between dimensional weight and actual weight. In simple terms, if your package is light weight but large (like a canvas painting), you'll be paying more.
UPS, FedEx and USPS.