Best Shipping Box Strengths for FedEx and UPS

When shipping your items through FedEx and UPS, you must ensure the boxes you use are durable enough to make it through the transportation process without breaking. A great way to achieve this is by understanding the best box quality and type to use for your specific needs. 

How Is Box Strength Determined? 

The strength or quality of a box is determined by a combination of the edge crush test (ECT) and the Mullen test. These industry standards are both designed to measure the amount of pressure a box can take before it breaks, but the methods differ for each test. 

The Edge Crush Test (ECT)

The edge crust test determines the strength of a corrugated cardboard box, particularly against crushing. During the test, a box receives cross-directional force while it’s vertical to see how much pressure it can withstand before it fails. Depending on the outcome of the tests, the boxes will receive an ECT rating, with higher ratings corresponding to higher strength. For example, a box with a 32 ECT rating can hold up to 65 pounds, while a box with a 51 ECT rating could hold up to 120 pounds.

The Mullen Test 

The Mullen test measures the amount of external pressure the walls of a corrugated box can take before bursting. The bursting strength is measured in pounds per square inch (psi). Using the Mullen test will determine how well boxes might withstand shaking and pressure during transportation.

Single-Wall, Double-Wall and Triple-Wall Boxes

The difference between single-wall, double-wall and triple-wall boxes all lies in the level of thickness, which ultimately affects what they are used for:

Single-wall: A single-wall box only has a single layer of fluted material between its boards and is most commonly used type by e-commerce businesses. 
Double-wall: A double-wall box has two layers of flutes and offers additional strength, which makes it ideal for heavy-duty packaging. 
Triple-wall: A triple-wall box has three fluted sheets and is considered the strongest of the three types. Triple wall boxes are often used for storing and transporting extremely heavy items. 

Types of Boxes to Avoid 

Box quality plays an important role in how protected your items will be during transit. Here are a few boxes to avoid when choosing a shipping box: 

Boxes that don’t contain the ECT and Mullen test specifications
Boxes that don’t meet the standard rating of 32 ECT or 200 psi
Recycled or used boxes

Tips for Shipping Heavy and Large Items

Shipping heavy or large items presents its own set of challenges and requires many considerations. Here are a few tips to ensure the process goes accordingly: 

Use durable packaging: Use boxes that are specifically designed for durability and sealed securely.
Use multiple boxes:  Consider separating your items and storing them in multiple boxes to avoid making your boxes too heavy. 
Choose the right carrier: Make sure the carrier you use has a good track record of shipping heavy and larger items. 

Build Your Own Durable Custom Box Now

At Custom Box Now, we have years of experience manufacturing quality corrugated boxes and packaging. With us, you can create a custom box that meets your specific needs.

To get started, contact us today.