New Dimension Rounding Rule and Your Shipping Bill
- Whitecloud Fly
- Sep 23
- 2 min read
In e-commerce logistics, dimensional weight (DIM weight) is one of the most overlooked yet critical factors affecting shipping costs. Recently, many small package carriers have updated their package measurement rules — starting from August 18, 2025, all package dimensions must be rounded up to the next whole inch.
This small change may significantly increase your shipping costs.
1. What is Dimensional Weight (DIM Weight)?
Shipping charges are not only based on actual weight but also on package volume.The formula is:
DIM Weight = Length (inches) × Width (inches) × Height (inches) ÷ DIM Divisor
Most small package carriers use 139 as the DIM divisor.
The higher value between actual weight and DIM weight will be used for billing.
2. The New Rule: Rounding Up Instead of Rounding Off
Previously:
10.2 inches → 10 inches
10.6 inches → 11 inches
Now:
10.2 inches → 11 inches
10.6 inches → 11 inches
👉 In other words, any decimal value above 0.01 must be rounded up.
3. Real Case Example
Suppose a package has actual dimensions of:20.4 × 15.2 × 10.3 inches, weighing 18 lbs
Old Rule (Round Off)
Dimensions: 20 × 15 × 10 = 3,000 cubic inches
DIM Weight: 3,000 ÷ 139 ≈ 22 lbs
Billed at 22 lbs
New Rule (Round Up)
Dimensions: 21 × 16 × 11 = 3,696 cubic inches
DIM Weight: 3,696 ÷ 139 ≈ 27 lbs
Billed at 27 lbs
👉 Same package, but the new rule adds 5 lbs of billable weight.
4. Impact on Businesses
Hidden Rate Increase
A difference of just 0.2 inches could previously save 1 lb, but now that’s no longer possible.
Biggest Impact on Lightweight, Large-Size Items
Such as home goods, apparel, and electronic accessories — especially common for Amazon and Shopify sellers.
Higher Costs for Returns
Return shipments for bulky products may now cost significantly more than before.
5. How to Respond
✅ Review Packaging Strategies
Use right-sized boxes to reduce wasted space.
Consider foldable or compressible packaging designs.
✅ Check with Your Carrier
Ask if they provide a negotiated DIM divisor (e.g., 166 instead of 139).
Consider shifting some shipments to LTL or regional carriers.
✅ Notify Customers in Advance
Update shipping policies on your website to avoid disputes over return costs.
6. Conclusion
While this may look like a small adjustment — rounding up instead of rounding off — it could result in thousands of dollars in extra shipping costs per year for small and medium-sized e-commerce businesses.
Recommendation: Run a “new rule cost simulation” on your best-selling products today and prepare your packaging or pricing strategies before the rule takes effect.
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