Want to know how your shipping cartons can withstand the stresses of shipping? Corrugated shipping box strength testing can help you determine their true resistance to stacking, impact, and humidity. This article details each test method, its applicable scenarios, and simple tests you can perform at home.
Last updated: September 2025 | Estimated reading time: 7 minutes
This article will answer your questions
- ECT, BCT, Mullen and other core standards
- Laboratory and home testing procedures
- Practical tips to improve the strength of small shipping boxes
Why test the strength of shipping boxes?
Testing shipping cartons’ strength verifies how much they can withstand external forces during transportation, loading and unloading, stacking, and storage, ensuring the integrity of the products inside. This testing helps you select the optimal cardboard thickness and weight to easily navigate various challenges. Strong packaging can reduce returns and damage rates, saving you money.
ECT, BCT and Mullen burst strength are internationally recognized corrugated box strength test items.
Actual case: An exporter in Shenzhen reduced product loss rate by 25% through regular BCT testing.
What factors can weaken the strength of shipping boxes?
The number of cardboard layers, weight, stacking direction, humidity, usage time, damage during transportation, etc. will directly affect the strength of the transport box.
The shipping strength of single-layer, double-layer, and triple-layer cardboard varies significantly. The more layers there are, the stronger the shipping box.
The smaller the cardboard weight, the lower the compressive strength will be.
If cartons are stacked in the wrong direction, it will easily make the cartons soft.
The higher the moisture content of the carton, the lower its strength. For every 1% increase in moisture, its strength decreases by 9%.
Shock, vibration, bumps and improper handling during transportation can also weaken the strength of the cartons.
The longer a carton is used or stored, the less likely it is to withstand compression.
How to measure overall cabinet strength?
The box compression test (BCT) is a key measure of stacking load. A complete carton is placed between the two platens of a compression testing machine and squeezed evenly. The maximum pressure applied to the carton is recorded to determine the carton’s overall compressive strength. The entire test standard is based on GB/T 4857.4-2003.
ECT tests the edge compression resistance of cardboard and is the main reference factor for measuring its stacking strength.
BCT Data Sheet:
| Test Type | Typical Value | Real-World Meaning |
|---|---|---|
| BCT Single Wall | 200–300 kg | Standard e-commerce shipping box |
| BCT Double Wall | 400–600 kg | Heavy-duty export carton |
| Safety Factor | 1.6× | Extra margin for transport shocks |
How to perform Edge Compression Testing (ECT)?
ECT measures lateral stacking strength.
A rectangular specimen of 25 mm x 100 mm is cut perpendicular to the corrugated direction. The testing machine gradually applies pressure until the specimen fails (collapses), thereby obtaining the maximum pressure value.
Calculation formula: ECT = F * 1000 / L (F: Maximum bearing pressure (Newton), L is the long side dimension of the specimen (mm))
ECT test reference standard: GB/T 6546.
How to perform burst strength test?
The Burst Test (Mullen) measures the ability to resist sudden impact or internal pressure.
Place a 6-inch square specimen in the hydraulic diaphragm tester and apply uniform pressure to cause the diaphragm to bulge upward until the specimen ruptures. Record the pressure at this point.
Tips: Over-calendered tissue paper may have high ECT but low Mullen, which may cause the box to break.
How to detect paper weight and thickness?
Method for measuring paper weight: Cut a 10cm x 10cm cardboard sample and weigh it to get the weight per square meter. The formula is as follows:
Gram weight = sample weight (g) / sample area (m²)
Use a micrometer to measure the thickness at multiple different locations and take their average to get the thickness of the cardboard.
Although grammage and thickness are related, they are not completely proportional. The higher the grammage and thickness, the stronger the cardboard.
How to perform simulated drop test?
Fill a carton and drop it from a height of 1 meter onto a flat concrete floor. Perform the corner drop, triangular drop, and flat drop tests to inspect the carton’s appearance and check for damage, deformation, or loss of function. This will help you assess whether the carton is qualified.
How to perform puncture test?
Secure a cardboard sample in the fixture of the puncture tester. A 1 kg steel cone impacts the carton wall at a speed of 1 m/s, subjecting the sample to various loads including tension, compression, and bending until it penetrates. This provides the maximum puncture force value, helping you determine the appropriateness of your cardboard selection and packaging design.
How to perform vibration testing?
The fully loaded cartons are placed on a vibration table and subjected to sinusoidal and random vibrations at 4.5 Hz for 60 minutes. The cartons are then inspected for structural integrity. This simulates truck transport and tests the strength of the glue lines.
How to test the cabinet strength in a humid or high humidity environment?
Place the cartons in a 90% RH environment for 4 hours. Once the moisture content reaches a stable state, remove the cardboard samples and conduct subsequent strength tests (ECT or BCT). This test will reveal how the carton’s performance changes under high humidity conditions.
How to choose the right test for your product?
- Light cargo: Choose ECT + drop test
- Re-stacking: select BCT + high humidity test
- Fragile: select burst + puncture test
Choose the packaging method that suits you based on the characteristics, weight, transportation environment and packaging of your product.
Practical tips for increasing the strength of shipping boxes
- Upgraded fluting type: BC or EB double corrugated for heavy goods
- Strengthened paper: Choose kraft paper with high ring pressure value
- Optimizing glue lines: Improving starch glue to enhance adhesion
Real-world case study: After switching from single-wall corrugated to double-wall corrugated packaging, a Shanghai Amazon seller increased their BCT from 250 kg to 480 kg, and reduced their damage rate by 30%.
New trends in corrugated box testing in 2025
- Automated ECT equipment improves detection speed and accuracy.
- AI-driven vibration table simulates real transportation routes.
- Environmentally friendly high-strength facial tissue reduces weight without sacrificing strength.
Market insights:
The global growth of e-commerce is driving demand for lightweight, high-strength shipping boxes, and recycled fiber strength technology continues to upgrade. This is also one of our core products.
FAQs
Yes, Amazon also requires that the packaging boxes meet the ECT 32 standard; when shipping overweight goods, you need to consider ECT 44.
Yes. Use packages of known weight to verify that your package complies with the stacking or drop test methods described above.
There is no unified standard for this. We test each batch of new paper at each factory or at least once a quarter to ensure stable strength.
Conclusion
- Key tests: ECT, BCT, Mullen
- Main risks: humidity, weak glue line, poor fiber quality
- Action: Select appropriate test based on cargo weight and shipping environment.
Next step: Schedule lab ECT and BCT testing for your next batch of cartons, or perform a simple drop test at home to catch problems early.
About XiangGe Package
We specialize in designing and producing custom corrugated shipping cartons, performing complete ECT, BCT, and Mullen testing to ensure our export quality and high strength performance.
Contact us for free samples or professional advice.
Last updated: September 2025
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