Dimensional 'Weight' Explained

Dimensional weight, or dim weight, has always been around for the air shipping industry. In 2007, ground carriers began charging for dim weight to protect themselves from the cost of transporting lightweight, but bulky packages. The term dimensional “weight” is somewhat of a misnomer. The volume or “dimension” is what’s actually being measured, but this is converted to into a theoretical weight – what the package could be expected to weigh given how much space it takes up.

For packages larger than 3 cubic feet, carriers will calculate the dimensional weight and charge whichever is greater – the actual weight or the dim weight. To find out which rate you’ll pay, you must divide the cubic inches of the package by the dimensional factor for ground shipping (166; air carriers use a dimensional factor of 139).
Let’s say you have a package measuring 25” x 20” x 20” that weighs 50 lbs. and you want to ship it by ground.

  • Multiply all of the sides together to find how many cubic inches the box occupies (10,000).
  • Divide the cubic inches by the dimensional factor of 166 (round up to the nearest whole number).
  • The dimensional weight of the package comes out to 60 – that’s more than the actual weight, so you would be charged for the dimensional weight.

Both FedEx and UPS recently announced that dimensional weight rules would apply to all shipments beginning in 2015. Depending on the packages you ship, your shipping expenses may increase. To combat that, we’ll cover some tips to help keep your dimensional weight shipping costs down in our next blog post.

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