ECT vs Burst Equivalence Chart

What it is

Corrugated board is graded by one of two tests. Edge Crush Test (ECT), per TAPPI T 811, measures how much edge load a strip of board carries before it crushes, in pounds per inch. It tracks stacking strength. Mullen burst, per TAPPI T 810, measures the pressure that ruptures the board face, in pounds per square inch, shown as "200#". It tracks puncture and rough-handling resistance. ASTM D4727 covers corrugated and solid fiberboard sheet stock. Box makers and buyers often pair one ECT grade with one burst grade, but the two tests measure different things.

How to read it

1. Find the grade on the Box Maker's Certificate on the bottom flap.
2. Find that grade in the matching column below.
3. Read across to the grade commonly offered by the other method.
4. Decide whether stacking (ECT) or handling (burst) matters more for the shipment.

Common single-wall pairings

These pairs come from how carrier classification rules grouped the two methods. They are not conversion factors.

Key points

• A 32 ECT box and a 200# box may perform very differently. ECT boards often use lighter liners, so they can have less puncture resistance. Burst boards may have less stacking strength.
• Pick ECT when boxes are palletized and stacked. Pick burst when boxes travel one at a time through rough parcel or LTL handling, or hold dense items.
• Size limits and gross weight limits are printed on the Box Maker's Certificate. Use the certificate and the current carrier rules, not this chart, for those limits.
• Humidity and time under load reduce stacking strength for both grades.
• Write the test method into the spec. "200# or equal" invites substitution.

Common mistakes

• Treating 32 ECT and 200# as the same board.
• Switching a parcel shipper from burst to ECT board to save cost without a drop or handling trial.
• Comparing an ECT grade from one flute size with a burst grade from another.
• Ignoring the double-wall grades, which have their own pairings.

Governing standards: TAPPI T 811 (edge crush); TAPPI T 810 (bursting strength); ASTM D4727 (corrugated and solid fiberboard sheet stock); NMFC Item 222 and UFC Rule 41 for carrier packaging rules.

Reference only. Verify against the current governing code or standard, the manufacturer's data and the project documents before use. Apps for Distributors disclaims liability arising from reliance on this reference.