ECT vs Burst Test: How to Read Carton Specs Without Getting Bullshitted
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Every carton spec sheet shows a "test" rating like 200lb or 32 ECT. Salespeople use them interchangeably; they're not. Here's what each actually measures, why one matters more depending on your use case, and how not to overpay for a test rating you don't need.
Burst test (the older standard)
Burst test (Mullen test) measures how much pressure per square inch the cardboard can take before rupturing. Think of pressing your thumb through the face until it punches a hole — burst test is how much PSI it takes to do that.
Common ratings: 200lb test (≈200 PSI burst), 275lb test, 350lb test for triple-wall.
What burst test is good at measuring: resistance to puncture, sharp impact, drop damage where the corner takes a sharp hit.
What it does NOT measure well: stack strength. A 200lb-test box can fail under pure compression long before its burst rating would suggest.
ECT (Edge Crush Test) — the modern standard
ECT measures how much weight per linear inch of edge the cardboard can support before crushing. It directly measures vertical compression strength — which is what matters when boxes are stacked on a pallet 8-10 high.
Common ratings: 32 ECT (the workhorse for most ecommerce/3PL), 44 ECT (heavier-duty), 55 ECT (industrial/double-wall).
What ECT is good at measuring: stack strength, compression damage during freight, pallet-stack durability.
What it does NOT measure well: puncture resistance from sharp impact (where burst test still matters).
The cheat-sheet conversion
The two systems aren't directly equivalent, but for most general-purpose shipping cartons, the rough comparison is:
| Burst test | Comparable ECT | Typical use |
|---|---|---|
| 200lb test | 32 ECT | General ecommerce, 3PL repeat cartons, mid-weight shipping |
| 275lb test | 44 ECT | Heavier products, heavier pallet stacks, harsher freight |
| 350lb test | 55 ECT | Industrial, machinery, parts, triple-wall constructions |
When to pay for higher ratings
Stick with 32 ECT / 200lb test if:
- Your products are under 30 lbs each
- You're shipping single-package parcel via UPS/FedEx (not stacked deep)
- You're a 3PL where boxes aren't stacked more than 6-8 high in racking
- You don't see compression damage in your returns/damage logs
Step up to 44 ECT / 275lb test if:
- Products are 30-50 lbs each
- You ship LTL freight with pallets stacked 10+ high
- You have visible compression damage on bottom-pallet boxes
- You're shipping into harsher climates (humidity weakens corrugated)
Triple-wall / 350lb / 55 ECT only if:
- Products over 50 lbs (industrial parts, machinery, durable goods)
- Pallets stacked very deep or transferred multiple times
- Outdoor staging where boxes face weather
The cost trap most buyers fall into
Most ecommerce and 3PL operations specify 275lb test "for safety" when 200lb test would protect their goods just fine. The premium is real — 275lb test cartons run 15–25% more per unit at the same dimension. Multiply that across 10,000+ cartons/year and you're paying thousands extra for compression strength you'll never use.
Look at your damage logs. If less than 0.5% of shipments arrive with crushed cartons at 200lb/32 ECT, you don't need to upgrade. If you're at 1%+, run the math: cost of stepping up vs cost of replacement units + customer service time + reputation hit.
What SurePack stocks (and why)
Our hero stock SKUs (SP-22146, SP-12126, SP-644) are 200lb test / 32 ECT C-flute single-wall. That's the right default for 80% of the repeat-cycle warehouse and 3PL use cases. Custom orders we'll spec to whatever ECT/burst your application needs — including double-wall and triple-wall configurations sourced direct from our vendor partners.
If you're staring at a competing quote and trying to figure out whether the spec is right, send us the spec sheet — we'll tell you straight whether you're under-protected, right-sized, or paying premium for protection you don't need.
Get a spec consultation + quote →
Questions? Ted at SurePack: 702-618-9018 · sales@surepackusa.com