Dimensional Weight

What Is Dimensional Weight?

Dimensional weight, often shortened to DIM weight, is a calculated weight based on a package's size rather than how heavy it actually is. Carriers use it because a large, lightweight box takes up as much space on a truck or plane as a heavy one. By pricing on space as well as weight, carriers make sure bulky parcels pay for the room they occupy.

How It Works

To calculate dimensional weight, the package's length, width and height are measured, typically rounded to the nearest whole inch, then multiplied together to get cubic size. That number is divided by a divisor set by the carrier. The result is the dimensional weight. The carrier then compares it to the actual scale weight and charges based on whichever is greater, which is called the billable weight.

Divisors and rules vary by carrier and service and can change, so brands should always check current carrier rate guides.

• Measure length, width and height of the packed box.
• Multiply the three dimensions together.
• Divide by the carrier's DIM divisor.
• Compare to actual weight; the higher number is billed.

Why It Matters for Ecommerce Brands

Dimensional weight is one of the biggest hidden drivers of shipping cost. A brand that ships a light product in an oversized box can end up paying for a much heavier package than it really is.

For example, a pillow or a hat in a big box may weigh very little but be billed as if it weighed several times more. Switching that product to a smaller box or a poly mailer can lower the billable weight considerably. Reviewing packaging sizes for best-selling SKUs is often one of the quickest ways for a brand to reduce postage costs without changing carriers.