ECT & box strength: how strong a box do you need?
4 min read
ECT vs burst strength, single vs double wall, and how to match box strength to your product weight.
Two ways strength is measured
Corrugated strength is rated two ways. Edge Crush Test (ECT) measures stacking strength, the force the board's edge can take, reported as a number like 32 ECT or 44 ECT. Burst strength (Mullen test) measures resistance to puncture, reported in pounds like 200# or 275#. ECT matters most for stacking and shipping; burst matters for rough handling and puncture.
Common grades
32 ECT / 200# single-wall handles most retail and ecommerce shipments up to roughly 65 lb. 44 ECT / 275# single-wall steps up for heavier or denser loads. Double-wall adds a second fluted layer for the heaviest, most fragile, or highest-stacked shipments.
Single vs double wall
Single-wall is one fluted layer between two liners, the right call for the vast majority of boxes. Double-wall is two fluted layers, used for heavy product, long-distance freight, or boxes that get stacked high in storage.
Match strength to your load
Heavier and denser contents, taller stacking, and rougher handling all call for higher ECT or double-wall. Every product page lists the ECT rating, burst strength and wall type so you can match the box to the job, no guesswork.
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FAQ
What does 32 ECT mean?
It's the Edge Crush Test rating, a measure of stacking strength. 32 ECT is a common single-wall grade suitable for most retail and ecommerce shipping.
ECT or burst strength, which matters more?
ECT (stacking strength) matters most for shipping and storage where boxes are stacked. Burst strength matters more for puncture and rough handling. Many boxes are spec'd by both.
When do I need a double-wall box?
For heavy or dense products, long freight trips, or boxes stacked high in storage. Double-wall adds a second fluted layer for extra strength and protection.