Why did DIM prices increase? Lighter weight, lower density packages are comparatively less profitable for carriers because they take up so much space relative to the price charged per package (based on weight alone). Looking for ways to adjust this model, carriers started using dimensional (DIM) weight rates. DIM weight rates allow carriers like USPS to establish a minimum charge for the cubic space a package occupies.

When did the USPS DIM change go into effect? The USPS DIM change went into effect on June 23, 2019. The current divisor for USPS is 166 (changed from 194).

Are there any other changes to DIM pricing? Yes. The USPS made the following changes to DIM pricing:

  • USPS added dimensional (DIM) weight pricing to Priority Mail zones Local and 1-4. DIM weight pricing now applies to all zones. 
  • USPS added DIM weight pricing to Priority Mail Express®. 
  • USPS added DIM weight pricing to Parcel Select.

Did all carriers changing their DIM weight pricing? FedEx and UPS adjusted their DIM pricing in 2018. USPS DIM rates are the only ones that changed on June 23, 2019.

How does DIM weight get calculated? DIM weight is calculated by multiplying the length by width by height of each package (in inches) divided by carrier divisor for shipments.

  • As an example, a 1 lb items that is 16” x 12” x 10” is 1,920 cubic inches. This number gets divided by the carrier divisor. 1,920/166 =  11.57 lbs., which rounds up to 12 lbs. The 12 lbs. is the DIM weight, which will be used for rating your package.
  • Alternatively, if the actual weight of this package were 13 Ibs then it would be used for rating you package instead of the 12 lb dimensional weight.

We created a tool to help you calculate.

How is DIM weight determined for nonrectangular parcels? For polybags and other nonrectangular parcels, the length, width and height are measured at the longest points to calculate the volume. However, the volume in inches is then multiplied by 0.785 before determining the DIM weight. 

  • As an example, a 1 lb item in a polybag that is 16” x 12” x 10” at the longest points is 1,920 cubic inches. This number gets multiplied by 0.785 to 1,507 before being divided by the carrier divisor. 1,507/166 =  9.09 lbs., which rounds down to 9 lbs. The 9 lbs. is the DIM weight, which will be used for rating your package and is 3 lbs. less than what would have been used had the package been rectangular.

What size packages qualify for DIM weight pricing?

  • For USPS, packages starting at 12” x 12” x 12” and up qualify.
  • Comparatively, for UPS and FedEx, packages starting at 6” x 6” x 6” and up qualify.

What role does weight play in calculating cost? Carriers take the DIM weight and the physical weight and choose the higher of the two to determine the final calculation.

What are some ways to minimize costs?

  • Choose the right box size. Don’t ship air.
  • If you need a filler, be sure it is lightweight. Don’t use more than you need to protect the contents.
  • Don’t overstuff the box. Sometimes splitting a shipment into two boxes is more economical.

What happens if the DIM weight is calculated incorrectly? If a USPS package is calculated incorrectly, postage will be due upon arrival at recipient’s address or returned to sender for insufficient postage.

Still have questions? You can find more detailed information here.

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