What Is ECT (Edge Crush Test)?
Updated · Vorex Packaging
ECT, or Edge Crush Test, is a measure of how much force corrugated board can take on its edge before it crushes. It is reported in pounds per inch of edge and mainly predicts how well a box resists stacking pressure, so it is the rating most often used to specify modern shipping and mailer boxes.
In the edge crush test, a small sample of corrugated board is stood on its edge and pressed until it fails. The result tells you how much compression the board can carry, which is closely linked to how much weight a box can bear when boxes are stacked in a warehouse or truck.
Common ratings
- 32 ECT is a widely used single-wall rating for everyday shipping boxes.
- 44 ECT and higher are used for heavier single-wall loads.
- Double-wall board reaches higher ratings for heavy or stacked goods.
ECT vs burst strength
ECT measures stacking strength. Burst strength (the Mullen test) measures resistance to puncture and rough handling. Boxes are usually rated by one or the other, and the box maker's certificate stamped on the bottom flap shows which. For most e-commerce shipping, ECT is the more useful number because stacking is the main stress. Tell your supplier the product weight and how orders ship so they can recommend a suitable board.
