ECT vs Mullen Test for Box Strength
Difference Between Edge Crush Test and Mullen Test
The Edge Crush Test rates how much weight can be stacked vertically on a box without damage and the Mullen Test rates how much force it takes to puncture a wall of the box. ECT rating is important to consider when stacking boxes, while Mullen rating is important for sharp & irregularly shaped items. See below for recommended ratings.
Mullen Test (Burst Test) for Box Strength
The Mullen Test (Burst Test) remains essential for evaluating a box’s resistance to punctures and ruptures—critical in today’s shipping environment where packages face rough handling, collisions, and sharp impacts. Unlike the Edge Crush Test (ECT), which measures stacking strength, the Mullen Test simulates real-world hazards like conveyor belt drops and crushing against uneven loads. A higher Mullen rating (e.g., 200+ psi) ensures your box can withstand external forces, preventing damage to products during transit.
While ECT is ideal for palletized shipments, the Mullen Test is indispensable for mixed freight, automated sorting systems, and high-impact handling. For maximum protection, many manufacturers now use both tests—ECT for vertical compression and Mullen for puncture resistance. Choosing the right balance between these ratings ensures your packaging survives the journey intact, keeping products safe from warehouse to doorstep.
Nelson Container uses these tests often on the large- and jumbo-sized packaging produced on our new flexo-folder/gluer:
Edge Crush Test (ECT) for Box Strength
The Edge Crush Test (ECT) measures how much weight a box can support vertically before its edges collapse—a critical factor in modern shipping where palletized loads and warehouse stacking are the norm. Unlike the Mullen Test (which evaluates puncture resistance), ECT directly correlates to real-world B2B logistics, where boxes endure heavy compression during transit and storage. Common ECT ratings include 32 ECT for single-wall boxes, 44-48 ECT for double-wall, and 60-90 ECT for heavy-duty triple-wall corrugated packaging. A higher ECT rating (e.g., 55 ECT = 55 lbs of edge pressure resistance) ensures boxes maintain structural integrity under stacked loads, preventing costly collapses.
As supply chains prioritize efficiency, ECT has become the preferred standard over traditional burst tests for most shipping scenarios. Its precision in predicting real-world stacking performance makes it indispensable for manufacturers, distributors, and e-commerce brands. When selecting packaging, always match the ECT rating to your product’s weight and expected handling conditions—because in today’s logistics, strong edges mean safe deliveries.
Edge crush testing is generally the test you want to be done when testing your package strength for B2B shipping, especially if the packages are medium- to small-sized and going to be stacked on top of one another. This is where corrugated provides a significant advantage.
Recommended Ratings Based on Weight
| Max. Suggested Load/Box | Min. Edge Crush Test | Mullen (Burst) Test |
|---|---|---|
| 35 lbs. | 26 ECT | 150# |
| 50 lbs. | 29 ECT | 175# |
| 65 lbs. | 32 ECT | 200# |
| 95 lbs. | 44 ECT | 275# |
| 120 lbs. | 55 ECT | 350# |
| Max. Suggested Load/Box | Min. Edge Crush Test | Mullen (Burst) Test |
|---|---|---|
| 100 lbs. | 48 ECT | 275# |
| 120 lbs. | 51 ECT | 350# |
| 140 lbs. | 61 ECT | 400# |
| 160 lbs. | 71 ECT | 500# |
| 180 lbs. | 82 ECT | 600# |
| Max. Suggested Load/Box | Min. Edge Crush Test | Mullen (Burst) Test |
|---|---|---|
| 240 lbs. | 67 ECT | 700# |
| 260 lbs. | 80 ECT | 900# |
| 280 lbs. | 90 ECT | 1100# |
| 300 lbs. | 112 ECT | 1300# |
Tested & Approved Triple Wall Packaging
Triple wall corrugated boxes are the heftiest boxes on the market. Designed to withstand heavy weight and protect delicate products, these boxes are the perfect solution for shipping fragile items. Adding protective foam inserts will ensure that your fragile products stay as safe as possible. All triple-walled packaging is tested and approved through the ECT and Mullen tests for strength. For large shipments, order our corrugated packages in bulk.
Nelson Container will even make your custom designed package official with ECT/Mullen BMC mark printing. Combined with our inner foam packaging, your products will be protected inside and out during transit.
Check out our ISTA Testing page for more package testing information.
What are
Edge Crush Tests and Mullen Tests Used For?
Both the edge crush test (ECT) and Mullen test are used to test the strength of a box, and both of these tests have their place in the world of packaging. The Edge Crush Test (ECT) and Mullen Test (Burst Test) serve distinct but equally vital roles in packaging strength evaluation. ECT measures a box's ability to withstand vertical stacking forces, making it the go-to standard for palletized shipments and warehouse storage. With ratings like 32 ECT (single-wall) up to 90+ ECT (triple-wall), this test directly correlates to real-world performance in B2B logistics and e-commerce fulfillment where boxes endure compression during transit and storage.
Meanwhile, the Mullen Test evaluates a box's resistance to punctures, impacts, and internal pressure – critical for packages facing rough handling, sharp objects, or shifting contents. With ratings from 125 psi (light-duty) to 300+ psi (heavy-duty), it's particularly valuable for retail packaging, irregularly shaped items, or mixed freight shipments. While ECT ensures boxes won't collapse under weight, Mullen guarantees they won't burst or puncture during handling. For optimal protection, many manufacturers now specify both tests to address all potential shipping hazards.
Lucky for you, Nelson Container has an in-house ISTA testing lab with both Mullen Test and edge crush test capabilities so we don't need to outsource to a third-party company. In-house testing saves time and money for us, and we pass those savings on to you.
"Partners" means we both benefit.
Small to medium-sized boxes that will be stacked on pallets are best tested using the ECT, and large to jumbo-sized boxes loaded directly onto trucks for quick B2B shipping are best tested using the Mullen Test.
