51 ECT vs 61 ECT: side-by-side numbers
61 ECT board crushes at 61 lb per inch of edge against 51 for 51 ECT, so in BC double wall a 61 ECT box is estimated 20% stronger in compression at any size. Whether that is worth it depends on load, stack height and storage time.
Estimated compression at 10 sizes
| Inside, in | 51 ECT BC | 61 ECT BC | Difference |
|---|---|---|---|
| 8 × 6 × 4 | 840 | 1,005 | +165 lbf |
| 10 × 8 × 6 | 953 | 1,139 | +187 lbf |
| 12 × 12 × 12 | 1,100 | 1,316 | +216 lbf |
| 14 × 10 × 8 | 1,100 | 1,316 | +216 lbf |
| 16 × 12 × 10 | 1,188 | 1,421 | +233 lbf |
| 18 × 12 × 12 | 1,230 | 1,471 | +241 lbf |
| 18 × 18 × 18 | 1,347 | 1,611 | +264 lbf |
| 20 × 16 × 14 | 1,347 | 1,611 | +264 lbf |
| 24 × 18 × 18 | 1,455 | 1,741 | +285 lbf |
| 24 × 24 × 24 | 1,556 | 1,861 | +305 lbf |
Boxes high at 30 lb per box
| Inside, in | 51 ECT | 61 ECT |
|---|---|---|
| 10 × 8 × 6 | 20 | 23 |
| 16 × 12 × 10 | 24 | 29 |
| 24 × 18 × 18 | 30 | 35 |
Column stacked for 30 days with Packgent's default 40% storage loss (an assumption): ⌊BCT × 0.6 ÷ 30⌋ + 1.
Choosing between them
Pick the lower grade when the stack is short, the load light or the box is used once. Move up when boxes sit in storage for weeks, see humid warehouses, are interlocked or overhang the pallet, because each of those cuts usable strength. The stacking calculator shows which grade your conditions need.
Sources
- Foster, G. (1997). "Boxes, Corrugated." In Brody & Marsh (eds.), The Wiley Encyclopedia of Packaging Technology, 2nd ed. Wiley. ISBN 0-471-06397-5 (table reproduced in Wikipedia, "Corrugated fiberboard")
- Packaging Corporation of America: Profiles with a purpose
- McKee, Gander & Wachuta (1963), Paperboard Packaging 48(8)
Last reviewed . See all sources and how Packgent computes.