What Is ECT?
ECT stands for Edge Crush Test, a standard measurement of how much force a corrugated board can take on its edge before it crushes. It is measured in pounds per linear inch of board.
ECT relates closely to stacking strength: how well a box resists buckling when weight sits on top of it. That makes it the specification to look at when boxes will be palletized and stacked in a warehouse or truck.
The Common Ratings
32 ECT is the common rating for single wall boxes. It is the usual starting point for e-commerce, retail shipping, and general light-duty use, and it is often paired with a 200# burst rating.
44 ECT is a step up in strength, used in heavy single wall and lighter double wall boxes. Check the certificate to see which you are getting.
48 ECT is a common double wall rating, used where heavier contents or more serious stacking are involved.
Heavier double wall and triple wall boards carry higher ratings and suit industrial packaging. Ratings vary by maker, so read the certificate and ask the supplier for rated capacity.
ECT vs. Burst Strength
Older specifications used burst strength, also called the Mullen test, shown as a # rating like 200# or 275#. Burst strength measures how much pressure the board takes before it ruptures.
ECT is the more common specification now because stacking performance matters so much in modern supply chains. Burst strength is still relevant for shipments facing rough handling or point impacts.
How to Choose
Start with these questions:
- Is the item light and shipping by parcel? Start with 32 ECT single wall.
- Is it heavier, or will boxes sit stacked? Look at 44 ECT or 48 ECT.
- Is it heavy, dense, or industrial? Look at heavier double wall, triple wall, or a gaylord.
If you are between two options, the stronger box is usually the safer choice. Remember that ratings describe a box as it was made, so a used box should be judged on its condition as well as its certificate.