May 31, 2026
USPS Dimensional Pricing Is Changing July 12
Fractions round up. Bulky boxes may cost more.
I came across an industry update from Supply Chain Dive about USPS changing how it calculates dimensional (DIM) pricing starting July 12.
I wanted to share the quick, plain-English version for our customers.
What is DIM pricing (in normal-people terms)?
Sometimes shipping isn't priced just by what a box weighs on a scale—it's priced by how much space it takes up. That's why a big, lightweight box (pillows, comforters, big gift items, etc.) can cost more than you'd expect.
What's changing on July 12
USPS is making two updates that can affect larger packages:
- •Rounding up fractional inches: a box measuring 12.2 inches will be treated as 13 inches for pricing calculations.
- •DIM divisor changing to 139 (from 166): a smaller divisor can make the calculated DIM weight higher, which can increase the price on bulky, lightweight shipments.
According to the article, this impacts Ground Advantage, Parcel Select, Priority Mail, and Priority Mail Express packages that are over 1 cubic foot (where DIM pricing applies).
What this means for you
This doesn't mean every USPS package will cost more. But if your shipment is large and light, you may see higher prices than you're used to—especially if it's just over a size threshold.
Our best advice (to avoid surprises)
- •Use the smallest box that safely fits your item.
- •Avoid extra empty space — dimensions matter more now.
- •If you're shipping something bulky, let us measure and compare options. Sometimes USPS is still best, and sometimes another carrier wins depending on the box size and destination.
If you want, bring the item in and we'll help you pick the best box and the most cost-effective shipping option before you pay.