Box Strength

Corrugated Moving Boxes Strength

The corrugated boxes have been around since 1870’s and has gone through evolutions with the advance of the manufacturing methods throughout the years. The improvement in the design and strength of the corrugated boxes has only added to their popularity in different industries searching for a lightweight but strong containers to move or ship a wide variety of products. The strength of the corrugated moving boxes is the result of adding a medium, known as fluting, to the linerboard. The fluting acts as a cushioning agent while adding a great strength to a simple linerboard which by itself is nothing more than a thick paper.

There are two distinctly different methods to measure the strength of corrugated boxes. The Mullen Test and Edge Crush Test or ECT.

Mullen Test

The Mullen Test was the first method to measure the strength of the corrugated cardboards. The idea behind the Mullen test was to measure the amount of weight necessary to burst or puncture a corrugated board. The strength measured as pound/per square inch, a #275 Mullen cardboard means it takes 275 Lbs. to rupture the wall of a corrugated box. The Mullen Test dates back to 1870’s and still used by some corrugated board manufacturers.

Edge Crush Test, ECT

Currently, the new testing measure of measuring strength in corrugated medium boxes instead of corrugated boards is The Edge Crush Test or simply known as ECT. This method was created in 1990’s and is the most common and widely used practice among the manufacturers of the moving box industry. The measuring of the strength of the corrugated moving boxes instead of the corrugated boards offers a better idea on what ECT needed to ship goods in different weights making them more cost-effective. The most commonly used ECT boxes are 32 ECT with a weight limit of 65 Lbs. followed by 44 ECT and 48 ECT.

Maximum Weight

Edge Crush Test, ECT

Mullen Bursting Test

20 Lbs.

23 ECT


35 Lbs.

26 ECT

150 #

50 Lbs.

29 ECT

175 #

65 Lbs.

32 ECT Most Common

200 #

80 Lbs.

40 ECT


90 Lbs.

44 ECT


129 Lbs.

50 ECT