ECT vs 200# burst: two tests, one job
ECT (Edge Crush Test) measures stacking strength — how much weight a box can support from above, which is what matters in palletized warehouse storage. 200# burst (Mullen) measures puncture resistance — how much pressure the wall takes before rupturing, which matters for rough parcel handling.
32 ECT and 200# burst are the two standard certifications for everyday shipping boxes and are roughly interchangeable for most loads up to 65 lbs. Rule of thumb: shipping single boxes via UPS/FedEx where boxes get thrown? Burst-rated is the classic choice. Stacking pallets in a warehouse? ECT is the number to watch.
Flutes: the wave inside the wall
| Flute | Thickness | Character |
|---|---|---|
| A | ~3/16" | Maximum cushioning and stacking strength |
| B | ~1/8" | Thin, rigid, prints well — mailers, bins, die-cuts |
| C | ~5/32" | The all-rounder — standard shipping boxes |
| BC (double wall) | ~1/4" | Heavy loads, export, 275# ratings |
Our stock cartons are C-flute kraft RSC unless noted; our mailers and bin boxes use B-flute for rigidity.
Single, double or triple wall?
Single wall (one fluted layer) handles the vast majority of shipments to about 65 lbs. Double wall (275#) steps in for 65–100 lb contents, export crating and heavy industrial parts. Triple wall approaches wood-crate strength for 200 lb+ contents. Our box list notes heavier-wall sizes, and our ATA-spec bulk containers cover the extreme end.
Don't forget the pads
A box is only as strong as its weakest face. Corrugated layer pads between tiers and over box bottoms add crush strength cheaply, and chipboard pallet pads protect the bottom layer from pallet-deck damage.
Find your size
Browse all 700+ stock corrugated box sizes with item numbers and bundle counts — searchable by dimensions. Need a size we don't stock, or custom printing? Custom boxes are made to spec.
Frequently asked questions
What does 32 ECT mean on a box?
ECT is the Edge Crush Test — 32 ECT means the box wall supports 32 lbs per inch of edge before crushing. It measures stacking strength, the key spec for palletized and warehoused freight, and is suitable for most shipments up to about 65 lbs.
Is 32 ECT the same as a 200 lb box?
They're roughly equivalent for typical use. 200# is a burst (puncture) rating, better for rough parcel handling; 32 ECT is a stacking rating, better for palletized storage. Most stock boxes carry one or the other and both handle everyday shipping.
When do I need a double wall box?
Use double wall (275#) for contents of 65–100 lbs, sharp or dense industrial parts, export shipments, or stacks stored long-term. Triple wall handles 200 lb+ contents.
Send us your product weight and dimensions — we'll match it to a stock size or quote a custom box.
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