55 ECT C flute: box compression and stacking table
55 ECT C flute pairs a 55 lb/in edge crush with a nominal 0.156 in caliper. As an empty 12 × 12 × 12 in box, the simplified McKee formula puts it near 884 lbf of top-to-bottom compression before any allowance for storage or humidity.
Compression, derated for storage time
| Inside size, in | 0 days | 10 days | 30 days | 90 days | 180 days |
|---|---|---|---|---|---|
| 8 × 6 × 4 | 675 | 425 | 405 | 371 | 338 |
| 10 × 8 × 6 | 766 | 482 | 459 | 421 | 383 |
| 12 × 12 × 12 | 884 | 557 | 530 | 486 | 442 |
| 14 × 10 × 8 | 884 | 557 | 530 | 486 | 442 |
| 16 × 12 × 10 | 955 | 602 | 573 | 525 | 478 |
| 18 × 12 × 12 | 989 | 623 | 593 | 544 | 494 |
| 18 × 18 × 18 | 1,083 | 682 | 650 | 596 | 541 |
| 20 × 16 × 14 | 1,083 | 682 | 650 | 596 | 541 |
| 24 × 18 × 18 | 1,170 | 737 | 702 | 643 | 585 |
| 24 × 24 × 24 | 1,250 | 788 | 750 | 688 | 625 |
0 days is the McKee estimate itself. Storage losses are Packgent's default assumptions (10 days 37%, 30 days 40%, 90 days 45%, 180 days 50%), not sourced values; edit them in the stacking calculator.
How many high can it stack?
Boxes high, including the bottom one, column stacked for 30 days, before humidity, interlock or overhang losses.
| Gross weight per box | 10 lb | 20 lb | 30 lb | 40 lb | 60 lb |
|---|---|---|---|---|---|
| Boxes high | 51 | 26 | 17 | 13 | 9 |
| Gross weight per box | 10 lb | 20 lb | 30 lb | 40 lb | 60 lb |
|---|---|---|---|---|---|
| Boxes high | 58 | 29 | 20 | 15 | 10 |
| Gross weight per box | 10 lb | 20 lb | 30 lb | 40 lb | 60 lb |
|---|---|---|---|---|---|
| Boxes high | 65 | 33 | 22 | 17 | 11 |
Boxes high = ⌊BCT × (1 − 0.4) ÷ gross weight⌋ + 1. A real stack needs further allowance for humidity, pattern and handling.
Neighbouring grades
| Grade | ECT change | BCT change, same flute and size |
|---|---|---|
| 48 ECT | -7 lb/in | -13% |
In McKee, BCT scales directly with ECT, so the percentage change in strength equals the change in ECT.
Freight rule limits
NMFC Item 222 ties each grade to a maximum gross weight and size for LTL shipping. Packgent has not published those limits yet because they could not be checked against the current tariff. See the Item 222 page for status.
Sources
- TAPPI T 811: Edgewise compressive strength of corrugated fibreboard (short column test)
- McKee, R.C., Gander, J.W. & Wachuta, J.R. (1963). "Compression strength formula for corrugated boxes." Paperboard Packaging 48(8): 149–159
- Flute calipers: Foster (1997), Wiley Encyclopedia of Packaging Technology
Last reviewed . See all sources and how Packgent computes.