DIM Weight Rule Changes in 2026

USPS: divisor 166 → 139, effective July 12, 2026

The headline change: USPS DIM divisor dropped from 166 to 139 in³/lb on July 12, 2026, and every dimension now rounds up to the next whole inch. For any package above the 1,728 in³ (one-cubic-foot) threshold, DIM weight rose roughly 19% overnight — a 24 × 18 × 12 in box went from 32 lb to 38 lb of DIM weight. The 70 lb DIM cap is unchanged. Details in the USPS DIM weight guide.

FedEx: surcharge triggers tightened on January 12, 2026

• Additional Handling gained a volume criterion: over 10,368 in³ (6 cubic feet) now triggers the charge, alongside the existing longest-side, girth, and weight criteria.
• Oversize gained two new triggers: volume over 17,280 in³ (10 cubic feet) and actual weight over 110 lb.
• Only the highest of Additional Handling, Oversize, and the Unauthorized Package charge applies — they no longer stack.

The FedEx dimension round-up rule predates 2026 — every dimension has rounded up to the next whole inch since August 18, 2025.

UPS: the split stayed, the rounding changed

No divisor change in 2026: Daily Rates still divide by 139 and Retail Rates by 166, and the 150 lb / 108 in / 165 in length + girth limits are unchanged. The quiet change is rounding — UPS now rounds every dimension up to the next whole inch, where its official page previously said "nearest." UPS does not publish when the change took effect. One flagged item: UPS Large Package volume and weight triggers (> 17,280 in³, > 110 lb) are encoded with an effective date of January 26, 2026, but per third-party consensus — an official UPS page stating them could not be retrieved, so treat that date as provisional.

DHL Express: one new Oversize criterion

On January 1, 2026, the DHL Oversize Piece surcharge gained a second criterion: second-longest side over 80 cm now triggers it, alongside the existing longest-side trigger (over 100 cm). The 5,000 cm³/kg volumetric divisor and 0.5 kg rounding are unchanged. DHL surcharge amounts remain country-specific and change annually.

What stayed the same

• FedEx divisor: 139 in³/lb (unchanged); US domestic Express maximums unchanged.
• UPS Daily / Retail divisor split: unchanged.
• USPS 1,728 in³ threshold and 70 lb DIM cap: unchanged — the divisor is what moved.
• DHL 5,000 cm³/kg divisor and 0.5 kg rounding: unchanged.

How DimCheck keeps up

Every rule on the carrier rules page carries its official source and its verification date; a weekly monitor fetches each official source, hashes the relevant text, and flags changes for manual review. If a carrier changes a rule after this guide was written, the calculator updates first, then this page.

Next steps

• Read the full USPS DIM weight rules
• Read the FedEx Additional Handling and Oversize guide
• Check your own packages against the current triggers
• See every rule with its official source