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  • Ankit Shah

A Guide to Calculate Weight Bearing Capacity of a Corrugated Box

Although the weight capacity of a corrugated box may not be a primary concern for individual purchases, it can significantly affect a business's profitability. The appropriate weight and strength of a box can lead to reduced supply chain expenses and increased profits.

Corrugated boxes consist of three distinct layers of paper: an inner liner, an outer liner, and fluting sandwiched between them. The fluting between the liner layers provides structural support and an additional layer of protection to the corrugated boxes. This method, also known as containerboard, is essential in providing the strength required to support the box's weight and safeguard the product inside.

The material used in making the corrugated box determines its strength. The box's strength is directly proportional to its density. Boxes with more walls are stronger than those with fewer walls. The manufacturer's label inside the box typically specifies the box's strength as single wall, double wall, or triple wall, providing information on its strength level.

The weight capacity of a corrugated box can vary because not all boxes are created equal. The box's outer and inner dimensions may differ, affecting the weight it can carry. Calculating the box size is crucial for informed logistics and supply chain management decisions, although box size does not influence the box's overall strength.

Box size is always stated in terms of inner dimensions rather than exterior dimensions, with length typically listed first, followed by width and depth. While the ideal proportion for corrugated boxes is 2:1:2 (L:W:D), boxes of various sizes are available for products that do not fit standard sizes.

To determine the weight capacity of corrugated boxes, the edge-crush test (ECT) is used. This test measures the compressive strength of the corrugated board by compressing a small section of the board between two rigid plates perpendicular to the direction of the flutes until peak load is achieved.

ECT-rated corrugated boxes require fewer raw materials, consume less energy, and produce less pollution throughout the package's life cycle than prior industry standards. The following are approximations for the weight a single-wall (3 Ply) corrugated box can support based on the ECT number indicated on the box's bottom:

32 ECT: 30 pounds

40 ECT: 40 pounds

44 ECT: 50 pounds

55 ECT: 65 pounds

Following are approximations for a double-wall (5 Ply) corrugated box based on ECT number:

48 ECT: 60 pounds

51 ECT: 80 pounds

61 ECT: 100 pounds

71 ECT: 120 pounds

82 ECT: 140 pounds

By using the weight capacity estimates based on the ECT number, businesses can make well-informed decisions about how much product to pack in a box or what size of corrugated box is required to fulfill their requirements. This enables businesses to make financially sound decisions regarding packaging and shipping their products.

With over 45 years of combined experience, Logipack is equipped to assist you in determining the most suitable style of corrugated box for your packaging requirements. With a range of 30-plus styles of corrugated boxes available, from basic Regular Slotted Containers (RSC) to self-erecting boxes and retail floor displays, we can offer the perfect corrugated box to meet your specific needs. Our team will work together with you to provide a customized solution that matches your budget and corrugated application requirements.


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