Starting August 18, 2025, FedEx and UPS will round every fractional inch up when measuring length, width, and height for dimensional (DIM) weight. Example: 11.1″ becomes 12″; 8.01″ becomes 9″. FedEx confirms the new rounding in its 2025 rate updates; UPS has matched the policy beginning the same date. More cubic inches means higher billable weights and more surcharge trips. This article breaks down what’s changing, who’s hit hardest, and the ways to protect margin.
Summary: What 2025 FedEx & UPS DIM Rounding Rule Means
Effective August 18, 2025, both FedEx and UPS will round every fractional inch up when measuring package length, width, and height before calculating dimensional (DIM) weight. Even small overages (e.g., 48.1″ → 49″) can significantly increase cubic volume, raise billable weight, and trigger Additional Handling Surcharges (AHS)—including FedEx’s 40-lb minimum billable weight when AHS–Dimension applies.
Shippers with lightweight, bulky SKUs and dimensions near key thresholds (12″, 18″, 24″, 30″, 48″) are most affected. The fastest ways to mitigate impact include right-sizing packaging, cartonization rules targeting whole-inch cutoffs, pack-station measurement SOPs, and lane-by-lane modeling across FedEx and UPS services using the correct DIM divisors (e.g., 139 vs. 166).
What is DIM weight?
Dimensional (DIM) weight prices a parcel by the space it occupies as well as its scale weight. Carriers compute a volumetric weight from the box size and charge the greater of actual weight vs. DIM weight.
The U.S. General Services Administration (GSA), which sets transportation and logistics policies for federal agencies, recognizes volumetric pricing as a standard freight practice used by carriers to align shipping costs with space utilization rather than mass alone—especially in parcel and small-package networks.
Formula (U.S. inches):
DIM weight (lb) = ⌈(Length × Width × Height) ÷ divisor⌉
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Common divisors: 139 (many negotiated/daily accounts) and 166 (some retail/counter accounts). Your contract controls the exact value.
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After DIM is computed, carriers round up to the next whole pound and compare to actual weight.
Example:
Box 12 × 9 × 7 in → volume 756 in³
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With divisor 139: 756 ÷ 139 = 5.44 lb → 6 lb DIM
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If actual weight = 4.2 lb, billed weight = 6 lb (DIM wins).
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If actual weight = 7.0 lb, billed weight = 7 lb (actual wins).
Why carriers use it: Light, bulky parcels (pillows, apparel, void-filled boxes) consume vehicle space; DIM weight aligns price with space usage, not just mass.
What is the DIM Rounding Rule?
Effective August 18, 2025 (FedEx and UPS), any fractional measurement of length, width, or height is rounded up to the next whole unit before applying the DIM formula.
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Example: 11.1″ → 12″, 8.01″ → 9″.
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This increases cubic volume used in the calculation, which can raise billable weight and push more shipments over dimension-based surcharge thresholds (e.g., >48″ longest side, >30″ second-longest side).
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The usual post-calculation step still applies: billed weight is rounded up to the next whole pound after DIM is computed.
What Exactly Is Changing With New FedEx & UPS DIM Rounding Rule?
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New rounding rule: any fraction of an inch (or centimeter) rounds up to the next whole number before DIM is calculated—for both carriers.
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Additional-handling thresholds stay the same, but the stricter rounding means more parcels will cross them (e.g., longest side > 48″ or second-longest side > 30″ at UPS). UPS
FedEx statement: “FedEx will round every fraction of an inch/centimeter up to the next-higher inch/centimeter.” FedEx
FedEx Actual Weight vs Rated Weight
Actual weight is simply what the package weighs on a scale, while rated weight (also called billable weight) is the weight used to calculate your shipping charges, and it’s usually the higher of the actual weight or the dimensional (DIM) weight. DIM weight is based on how much space the package takes up (length × width × height ÷ FedEx’s DIM divisor), so large, lightweight boxes often get billed at a higher rated weight than what the scale shows. In short: the scale number is actual weight, but your invoice is based on rated weight—whichever is greater, physical or dimensional.
Why does new FedEx & UPS DIM Rounding Rule matter?
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DIM weight grows because rounding up increases cubic inches before the divisor is applied. Billable weight is the greater of actual vs. DIM. (Divisors vary by carrier/account; consult your agreement.) Shopify
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Example of a common bump: a box measured at 11.1 × 8.5 × 6.2″ now rounds to 12 × 9 × 7″, which can push a shipment from ~5 lb to ~6 lb (≈ +20% billed weight before fees).
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More surcharges get triggered: Rounding can tip dimensions over thresholds such as UPS Additional Handling (>48″ longest side or >30″ second-longest side). FedEx’s Additional Handling – Dimension can also apply—and when it does, FedEx enforces a 40-lb minimum billable weight on the package.
FedEx example (Rounding + 40-lb minimum under AHS–Dimension)
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Measured: 48.1 × 12.0 × 6.0″ at 10 lb
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New rounding: 49 × 12 × 6″ (48.1 → 49)
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DIM divisor: FedEx uses a divisor per account/service; for illustration, 139.
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DIM = (49×12×6) / 139 = 25.38 lb → 26 lb billed
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But the package’s longest side > 48″, so Additional Handling – Dimension applies. Under FedEx’s 2025 Service Guide, rating is subject to a 40-lb minimum billable weight when AHS–Dimension criteria are met.
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Final billable weight: 40 lb, not 26 lb. FedEx
Why costs jump: that tiny 0.1″ overage now rounds to 49″, crossing the 48″ threshold and invoking a 40-lb minimum.
References: FedEx 2025 Rate Changes and FedEx 2025 Service Guide (non-standard shipment & AHS details).
UPS example (Rounding + Additional Handling thresholds)
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Measured: 48.1 × 12.4 × 8.2″ at 8 lb
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New rounding: 49 × 13 × 9″ (each fraction rounds up)
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UPS Daily illustration with divisor 139: DIM = (49×13×9)/139 = 41.24 lb → 42 lb billed
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UPS Retail/counter illustration with divisor 166: DIM = 34.54 lb → 35 lb billed
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Impact: Longest side > 48″ ⇒ Additional Handling likely applies (adds a surcharge). Unlike FedEx, UPS does not impose a 40-lb minimum billable weight specifically for AHS—your charged weight remains the greater of actual vs. DIM.
What to do after new FedEx & UPS DIM Rounding Rule take in affect?
Use this checklist to cut DIM weight and avoid surcharge triggers fast. It’s written for ops teams using Shopify, a WMS/OMS, and shipping with FedEx and UPS.
Audit & measure (first 48 hours)
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Pull last 60–90 days of parcels (dims, actual weight, service, zone, surcharges).
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Plot dims around whole-inch thresholds (12, 18, 24, 30, 48). Look for spikes at x.1–x.9″ that will now round up.
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Identify SKUs with low density (cubic inches per pound high) — prime DIM risk.
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Flag all parcels where longest side ≥ 47.9″ or second-longest side ≥ 29.9″ (AHS tripwires).
Right-size packaging (engineering quick wins)
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Prune carton sizes; eliminate overlaps. Add multi-depth cartons and on-demand or scored boxes to hit whole-inch targets.
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Swap boxes for poly/bubble mailers where protection allows. Use inserts to reduce void.
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Standardize pack-outs for top SKUs so finished dims land at whole inches (e.g., 12.0″, 18.0″, 30.0″, 48.0″).
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Set a “no air” rule of thumb (e.g., void ≤ 10%) and enforce with random checks.
WMS/OMS cartonization rules (prevent surprises)
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Update cartonization to target whole-inch cutoffs (e.g., never finish at 48.1″).
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Encode rules that prefer cartons keeping the second-longest side ≤ 30.0″ and longest side ≤ 48.0″ when possible.
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Refresh DIM tables and service maps per carrier; separate logic for UPS Daily (139) vs UPS Retail (166) if you use both.
Pack stations & measurement SOPs (process control)
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Calibrate dimensioners and scales (daily quick check + weekly full check). Document tolerances.
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Provide rigid rulers/gauges marked at common thresholds (12/18/24/30/48).
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Train on the new rounding rule and post a 1-page visual: “any fraction rounds up.”
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Add a packout sign-off for at-risk SKUs (spot-check dims before sealing).
Model by lane & carrier (decision support)
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For each top SKU/carton: compute pre- vs post-rounding DIM, then compare FedEx vs UPS billable weight.
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Watch for threshold trips: >48″ longest, >30″ second-longest (AHS risk) and service-specific limits.
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Maintain two calculators:
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UPS Daily (139) vs UPS Retail (166) paths.
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FedEx DIM plus AHS–Dimension scenarios (minimum billable weight risk when AHS is triggered).
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Choose services/boxes that keep you under thresholds while minimizing DIM weight.
Carrier strategy & contracts (protect the P&L)
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Ask reps about AHS definitions, waivers/caps, and any DIM divisor improvements for key lanes.
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Re-test Ground Economy/Ground Saver vs standard Ground after rounding; the winner can change by SKU/zone.
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Track hit rate of AHS by carrier and use the data in negotiations.
Pricing & CX alignment (no profit leaks)
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Align promotions and free-ship logic with post-rounding costs (consider tiered thresholds by category/size).
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Offer pickup/BOPIS or consolidated shipping for bulky items to avoid DIM shocks.
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Update returns packaging guidance so customers don’t incur oversize charges on the way back.
KPIs & governance (keep it sticky)
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Dashboard weekly: DIM % of orders, AHS rate, avg billed weight vs actual, $ per order, margin impact.
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Run A/B pack-outs for top 10 SKUs to validate savings.
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Add DIM checks to new-SKU onboarding so packaging decisions bake in whole-inch targets from day one.
Conclusion
Effective August 18, 2025, the “round any fractional inch up” rule increases the cubic inches used in DIM calculations. As a result, more parcels—especially light or bulky ones—will rate at higher billable weights and are more likely to cross Additional Handling thresholds (e.g., >48″ longest side, >30″ second-longest side). The impact varies by SKU mix, packaging, and service. Quantify it by modeling your top SKUs and lanes with the new rounding, your current DIM divisors (e.g., 139/166), and each carrier’s AHS logic. Mitigation should focus on: (1) right-sizing packaging, (2) cartonization rules that target whole-inch cutoffs, (3) calibrated measurement SOPs at pack stations, and (4) carrier/contract reviews where thresholds or surcharges drive outsized costs.
Jay Group can run a rapid DIM-impact audit and model pre- vs. post-rounding billed weights, powered by Manhattan WMS and Qlik Sense BI . We also capture exact box dimensions at pack-out and feed them into a custom box machine to right-size packaging and avoid 48.1″ pitfalls. When it makes sense, we optimize the carrier mix and leverage bi-coastal facilities (PA & NV) to reduce zones and soften DIM inflation.
FAQ: DIM Weight, Rounding & Surcharges
FAQ1: What is dimensional (DIM) weight, and how is it calculated?
Dimensional (DIM) weight prices a parcel based on the space it occupies, not just its scale weight. Carriers calculate DIM weight by multiplying length × width × height, dividing by a DIM divisor (such as 139 or 166), and rounding up to the next whole pound. The billed weight is the greater of actual weight or DIM weight.
FAQ2: What changed with the FedEx and UPS DIM rounding rule on August 18, 2025?
Effective August 18, 2025, FedEx and UPS now round every fractional inch up when measuring package length, width, and height before calculating dimensional weight. For example, 11.1″ becomes 12″. This increases cubic volume, raises DIM weight, and makes it easier for shipments to cross surcharge thresholds.
FAQ3: Does FedEx round up dimensional weight?
Yes. FedEx rounds each package dimension up to the next whole inch before calculating DIM weight, and then rounds the resulting DIM weight up to the next whole pound. Under the 2025 rounding rule, even small fractional measurements can materially increase the billed weight.
FAQ4: What is the difference between actual weight and rated (billable) weight at FedEx and UPS?
Actual weight is what a package weighs on a scale. Rated (or billable) weight is the weight used for pricing and is the greater of actual weight or dimensional weight. If DIM weight exceeds actual weight, carriers bill at the higher rated weight after rounding.
FAQ5: What is the FedEx and UPS dimensional weight divisor (139 vs. 166)?
For most U.S. domestic shipments, FedEx and UPS use a DIM divisor of 139 for daily or negotiated accounts. UPS retail or counter shipments often use a 166 divisor. The divisor used depends on the carrier, service level, and your specific contract, and it directly impacts how quickly DIM weight increases as package size grows.
FAQ6: How can shippers reduce costs from FedEx and UPS DIM rounding?
Shippers can reduce DIM-related costs by right-sizing packaging, targeting whole-inch dimension cutoffs, updating WMS cartonization rules, and auditing SKUs near key thresholds like 12″, 18″, 30″, and 48″. Modeling carrier costs by SKU and lane is essential to avoiding unexpected surcharges after the new rounding rule.
Rounding each side up increases the cubic inches, so the DIM figure rises. Since carriers bill the greater of DIM vs. actual, more packages price at higher billed weights. Rounding also pushes more shipments over surcharge thresholds.