Dimensional weight, or DIM weight, is a way for shipping companies to estimate the weight of a package by using its size. Very large or very heavy packages are more costly to transport, so the cost is typically determined by whichever measurement is larger between the DIM weight and the actual weight.
The package dimensions of length, width, and height are usually multiplied together to calculate the dimensional or volumetric weight of the package. The size of the package usually determines the shipping rate per cubic foot, and different box sizes are marked with different shipping costs.
Note: To determine DIM weight for UPS, Fed Ex, and DHL, multiply a package's length, width, and height in inches, then divide the resulting cubic inches by 139. For USPS, divide the resulting cubic inches by 166 only if the cubic inch value is greater than 1728.
If the actual weight of the package outweighs the DIM weight calculated using the standard formula, then the actual weight of the package is used as the billable weight for calculating shipping costs. Thus, the larger the package, the higher its shipping costs.