# USPS uses divisor 139 and rounds dimensions up

https://storecalc.com/en/updates/usps-dim-139.html

- Topic: Shipping
- Published: 2026-06-25
- Effective: 2026-07-12
- Checked: 2026-10-23

USPS now uses divisor 139 and rounds length, width and height up to whole inches; rectangular parcels use DIM only above 1,728 cubic inches after rounding. The same package may bill at a higher weight; this site’s USPS row models Priority Mail retail weight pricing.

## Our read

Bulky items such as hoodies and blankets are hit hardest. A 16 × 12 × 10 in box holding 5 lb now bills at 14 lb. The simplest fix for apparel is a poly mailer instead of a box: soft packs usually stay under 1,728 cubic inches, so dimensional weight never applies.

## Key dates

- 2026-06-25: Published
- 2026-07-12: New divisor and rounding take effect; Priority Mail Cubic's maximum dimension also rises from 18 to 22 inches
- 2026-10-23: We checked the official text

## Who is affected

- Sellers shipping US domestic parcels with USPS Priority Mail, Priority Mail Express, Ground Advantage or Parcel Select, at retail or commercial prices.
- Anyone boxing bulky goods such as hoodies, jackets, blankets or pillows in cartons over one cubic foot (1,728 cubic inches, about 12 × 12 × 12 in).
- Sellers who ship T-shirts and other thin items in poly mailers under 1,728 cubic inches are largely unaffected: below that line only actual weight counts.

## Run the numbers

The same 5 lb of goods in different packaging (illustrative, using the USPS rule in StoreCalc's billable weight calculator)

| Packaging | Rounded size (in) | Volume (cu in) | Billable weight |
|---|---|---|---|
| Carton 16 × 12 × 10 | 16 × 12 × 10 | 1,920, above 1,728 | 1,920 ÷ 139 = 13.8, rounded up to 14 lb |
| Carton measuring 15.2 × 11.5 × 9.4 | 16 × 12 × 10 (each side rounded up first) | 1,920, above 1,728 | Also 14 lb |
| Switch to a 16 × 12 × 9 carton | 16 × 12 × 9 | 1,728, not above | Actual weight, 5 lb |
| Poly mailer 18 × 14 × 4 | 18 × 14 × 4 | 1,008 | Actual weight, 5 lb |

Rows one and three differ by one inch of height, and billable weight drops from 14 lb to 5 lb. Postage depends on billable weight and zone; it is not estimated here.

[Recalculate in the Billable weight and packaging comparison](https://storecalc.com/en/ship/?u=in&al=16&aw=12&ah=10&am=5&aq=1&ashape=rect&bl=18&bw=14&bh=4&bm=5&bq=1&bshape=nonrect&focus=usps)

## What to do

- Re-run your usual carton sizes under the new rule: round every side up to a whole inch, then check whether the volume exceeds 1,728 cubic inches.
- Move borderline cartons down a size. In the example above, cutting the height from 10 to 9 inches takes 5 lb of goods from billing at 14 lb back to 5 lb.
- Use poly mailers for apparel where you can; when a carton is needed, size it to the packed goods and leave little empty space.
- If a 3PL or fulfillment service ships for you, ask whether its quotes already use divisor 139 and round-up dimensions.

## What the official text says

Quoted from the official text.

> The Postal Service is changing the DIM factor to 139 to determine the dimensional weight in pounds.

— [USPS Postal Bulletin 22705: DMM revision, competitive products pricing and mailing standards](https://about.usps.com/postal-bulletin/2026/pb22705/html/updt_001.htm)

> Round up (see 604.7.0) each measurement to the nearest whole inch.

— [USPS Postal Bulletin 22705: DMM revision, competitive products pricing and mailing standards](https://about.usps.com/postal-bulletin/2026/pb22705/html/updt_001.htm)

> If the result exceeds 1,728 cubic inches, divide the result by 139 and round up (see 604.7.0) to the next whole number to determine the dimensional weight in pounds.

— [USPS Postal Bulletin 22705: DMM revision, competitive products pricing and mailing standards](https://about.usps.com/postal-bulletin/2026/pb22705/html/updt_001.htm)

## Sources

- [USPS Postal Bulletin 22705: DMM revision, competitive products pricing and mailing standards](https://about.usps.com/postal-bulletin/2026/pb22705/html/updt_001.htm)
- [USPS Postal Bulletin 22705](https://about.usps.com/postal-bulletin/2026/pb22705/html/welcome.htm)

We checked the official text on 2026-10-23. Rules can change again; the latest official publication prevails.

## Related updates

- [FedEx rounds fractional dimensions up](https://storecalc.com/en/updates/fedex-dimension-rounding.html)