USPS DIM Weight Calculator (2026): Divisor, Rules & Rounding

USPS Ground Advantage and Priority Mail rectangular DIM for US domestic parcels. Cubic is a separate rate table.

USPS DIM at a glance

  • Divisor 139 when billed volume > 1,728 in³ (1 cubic foot). Below that, actual weight only.
  • Effective July 12, 2026 — DMM 283 §§1.4.1–1.4.2 and DMM 223 §1.4. Not 166.
  • Round each side up to a whole inch, then ceil(volume ÷ 139) if DIM applies.
  • Last verified: Notice 123 / DMM effective 12 July 2026. See changelog.

01Package Details

IN
IN
IN
LB
Volumetric Analysis1,120 in³ (0.65 ft³)
USPS Ground Advantage (÷139 if over 1 ft³)
0.0 lbActual Billed
Billed 14×10×8 in. Billable: 4 lb
UPS/FedEx DIM applies: Dimensional weight (9 lb) exceeds actual weight (3.2 lb). USPS Ground Advantage stays on actual weight unless billed volume exceeds 1,728 in³.
USPS Cubic Opportunity
This package may qualify for USPS Cubic pricing which charges by volume not weight. USPS Cubic could be cheaper than standard Ground Advantage at your zone. Check eligibility at the USPS Cubic Calculator.

When USPS actually bills DIM

After ceiling each side, if L × W × H is 1,728 in³ or less, Ground Advantage stays on rounded actual pounds. Cross 1,728 and DIM 139 competes with actual. That gate is why a fluffy 16 × 12 × 10 in box suddenly looks like UPS, while a 14 × 10 × 8 in box does not.

UPS Daily DIM → has no 1 cu ft skip. FedEx DIM → is still a 139 model pending a FedEx PDF. For Cubic (max 22 in, 20 lb) use the Cubic calculator, not this page.

Worked example: 16 × 12 × 10 in, 5 lb (Medium Carton preset)

Billed 16 × 12 × 10 = 1,920 in³ > 1,728, so DIM applies. ceil(1,920 ÷ 139) = 14 lb vs actual 5 lb → billable 14 lb. Contrast 14 × 10 × 8 in at 3.2 lb: billed volume 1,120 in³, DIM off, billable 4 lb. Cutting the medium carton height to 9 in lands on 1,728 exactly — DIM off in this engine because the rule is greater than 1,728, not greater-or-equal. That is the near-miss: one inch of height can drop you off USPS DIM entirely.

What these numbers are not

Notice 123 commercial cells and DMM DIM rules — not Retail Counter, not Cubic tiers, not fuel. Confirm on Postal Explorer before you buy a label. Divisor table: full carrier divisor article.

Frequently Asked Questions

What is the USPS DIM divisor in 2026?

139 when billed volume exceeds 1,728 in³, effective July 12, 2026. 166 is historical for these products, not current.

Does USPS use dim weight on small packages?

Not at or below 1,728 in³ billed volume. 14 × 10 × 8 in at 3.2 lb stays on actual (4 lb billed).

How does USPS round dimensions?

Each side up to a whole inch, then volume. DIM only if that volume is over 1,728 in³.

Can I negotiate my divisor with USPS?

No custom divisor in this tool. Cubic is a different product — open the USPS Cubic calculator for 22 in / 20 lb cartons.

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Verified July 12, 2026 — DMM 283 / Notice 123 commercial DIM 139 over 1 cu ft · See changelog