Corrugated Strength 101: Understanding ECT vs. Mullen Test for Heavy Duty Shipping

If you are shipping heavy equipment or stacking pallets high, you have likely seen the stamps on the bottom of your boxes: ECT and Mullen. Understanding these two ratings is the key to preventing box failure in transit and avoiding the costly product damage and customer complaints that come with it.

ECT stands for Edge Crush Test. It measures how much top-to-bottom compressive force a corrugated board can withstand before it buckles. ECT is expressed in pounds per linear inch, so a box rated 32 ECT can withstand 32 pounds of force per inch of its perimeter before the walls start to collapse. ECT is the most relevant rating for palletized freight where boxes are stacked under the weight of other boxes, because it directly measures the stacking strength that matters in that scenario.

Mullen Burst, also called the Burst Test, measures how much pressure it takes to puncture the face of the corrugated board from the outside. It is expressed in pounds per square inch. Mullen is most relevant for single-package parcel shipping where the box is handled individually, dropped, and subjected to impact forces rather than sustained compressive loads. If you are shipping products via UPS or FedEx as individual parcels, Mullen is the rating to pay attention to.

For most agricultural and food service applications involving palletized shipments, ECT is the more important specification. A 32 ECT single-wall box is standard for most produce and food applications. A 44 ECT or 48 ECT double-wall box is appropriate for heavier items like bulk bins of watermelons or heavy equipment parts. Over-specifying your boxes by buying a higher rating than you need costs money without providing real benefit, while under-specifying can result in pallet collapse and damaged goods.

Supply Carton can help you match the right box specification to your product weight, stack height, and shipping method. Call (469) 489-4999 or contact us online for a specification consultation and quote.