Understanding ECT (Edge Crush Test) vs. Burst Strength in Corrugated Packaging
If you’ve ever looked at a box maker’s certificate and seen numbers like 32 ECT or 200# Mullen, you’re not alone in wondering what they actually mean.
Both Edge Crush Test (ECT) and Burst Strength (Mullen Test) measure corrugated box performance — but they evaluate very different types of strength. Understanding the difference helps you choose the right packaging for your product without overspending.
At ADS Paper Supply, we guide customers through these specifications every day. Here’s a clear breakdown.
What Is ECT (Edge Crush Test)?
The Edge Crush Test (ECT) measures how much vertical compression a corrugated board can withstand before it collapses.
In simple terms:
ECT measures stacking strength.
During testing, a small section of corrugated board is compressed vertically until it crushes. The result (for example, 32 ECT or 44 ECT) indicates how well a box will hold up when stacked in a warehouse or on a pallet.
Why ECT Matters
Most shipments today are palletized and stretch-wrapped
Boxes are stacked multiple layers high
Warehouse storage often puts vertical pressure on cartons
If stacking performance is your biggest concern, ECT is typically the most relevant rating.
What Is Burst Strength (Mullen Test)?
The Mullen Test measures how much pressure the sidewall of a box can take before it bursts or punctures.
In simple terms:
Burst strength measures resistance to rupture.
A hydraulic diaphragm pushes against the corrugated surface until it bursts. Ratings are expressed in pounds per square inch (PSI), such as 200#, 275#, etc.
Why Burst Strength Matters
Rough handling during shipment
High risk of puncture or side impact
Heavier, dense products pressing against box walls
Historically, Mullen ratings were the industry standard before distribution shifted toward palletized stacking systems.
ECT vs. Mullen: Key Differences
| Feature | ECT | Mullen (Burst) |
|---|---|---|
| Measures | Stacking strength | Wall rupture resistance |
| Focus | Vertical compression | Puncture resistance |
| Best For | Palletized loads | Rough handling |
| Common Today? | Yes | Less common but still used |
Modern logistics environments typically prioritize ECT, especially in automated warehouses and large-scale distribution.
Why the Industry Shifted Toward ECT
Over time, supply chains evolved:
More palletized freight
Less individual box handling
Increased warehouse stacking
Because stacking became the dominant stress factor, ECT ratings became more practical and cost-efficient for most applications.
That said, certain industries — especially heavy industrial or export shipments — may still require Mullen-rated board.
Which One Do You Need?
The right choice depends on:
Product weight and density
Stacking height
Shipping method
Handling conditions
Storage duration
For many businesses, a properly specified ECT-rated box provides the right balance of performance and cost. But if puncture resistance is critical, burst strength may still be relevant.
Don’t Guess — Engineer It Correctly
Over-specifying leads to higher material costs. Under-specifying risks product damage.
At ADS Paper Supply, we help you evaluate your:
Product weight
Load configuration
Distribution environment
Cost targets
Then we recommend the board grade that fits your real-world needs — not just what’s traditionally ordered.
Final Takeaway
ECT = Stacking strength
Mullen = Puncture resistance
Most modern distribution favors ECT
The best choice depends on how your product moves through the supply chain
If you're unsure what those numbers on your box certificate really mean, we’re happy to walk you through them and make sure your packaging is optimized for protection and efficiency.