Dimensional Weight: Why Packaging Size Matters for Holiday Rush

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No matter the season—spring, summer, fall, or winter—holiday shopping means a burst of activity for retail businesses, eCommerce fulfillment centers, and third-party logistics (3PL) providers.

But from September onwards, when orders ramp up and the deadline to ship and deliver packages safely before December 24 feels tighter, it’s critical to focus on how you package your products to avoid unnecessary shipping costs.

Specifically, dimensional weight pricing and seasonal holiday fee schedules can unexpectedly drive up expenses. By understanding how these fees are calculated and optimizing your packaging strategy, you can reduce waste, avoid surprises, and protect your profit margins.

How Shipping Fees Are Calculated

Freight weight is the actual weight of the shipped package regardless of the size of the box. To discourage shippers from taking up unnecessary space with larger boxes, a DIM weight policy was adopted. 

Freight Weight

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Actual package weight

Dimensional (DIM) Weight

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Length x Width x Height/DIM Factor
(commonly 139 or 166)* 

*DIM factor may vary by carrier, distance, or shipping speed

PRO TIP: Use online calculators to estimate costs before shipping

What is Dimensional Weight?

DIM weight is essentially how much space your package takes up. It is determined by calculating the package dimensions (length x width x height) and dividing that number by the DIM factor. The resulting number is the billable weight.

The DIM factor, often 139 or 166, is a fixed number set by a carrier and is derived from a volume-to-weight ratio. A lower DIM factor leads to a higher DIM weight and can increase costs if you are shipping something lightweight but in a bulky package.

Here are a couple of scenarios to show how DIM weight can affect shipping costs.

PRO TIP: Compare different carriers' shipping rules, DIM factors, and coverage to determine who may have the best costs during the holiday season.

Why It Matters During Peak Holiday Shopping Season

While DIM weight calculations are used year-round, carriers levy holiday surcharges from September through late December. So, lightweight but bulky packages can incur higher fees if not efficiently packed. 

The result? Unexpected costs, delayed fulfillment, and lower profit margins during your busiest months.

PRO TIP: Review each carrier’s holiday surcharge fee schedules¹ and note when costs increase to help identify the best prices throughout the holiday shipping season.

Packing Tips to Avoid DIM Weight Surprises

Consider these packaging strategies to minimize or avoid costs:

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  PRO TIP: Audit your packaging materials for additional cost-effective ways of shipping that can reduce DIM weight. For example, use mailers instead of corrugated boxes for products that don’t need as much protection.
  
  

• Packaging Waste Reduction

• With Extended Producer Responsibility (EPR) regulations starting to go into effect, optimizing your packaging program for total cost of ownership, including materials and shipping, has never been more important. Reducing materials, minimizing unused space, and improving cube efficiency can lower both shipping costs and environmental impact.
  
  

• Final Takeaways

• Reducing dimensional weight costs starts with smarter packaging decisions. Businesses can decrease costs by “right sizing” their packages, using void fill and/or protective packaging strategically based on the contents, and regularly reviewing DIM factors and carrier costs.

• Whether you’re a manufacturer, retailer, or 3PL partner, optimizing packaging before peak season helps control costs, maintain efficiency, and ensure timely delivery all season long.

• Looking to optimize your packaging process? Request a free packaging assessment.

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• Source
• 1. Supply Chain Dive: UPS unveils 2025 holiday shipping surcharges