Stacking strength and safety factor calculator
Work out the compression strength a box needs for a stack, after losses for storage time, humidity, stacking pattern and overhang.
Calculator
Passes: 556 of 208 lbf
| Load on bottom box | (6 − 1) × 25 = 125 lbf |
|---|---|
| 30 days in storage | −40% |
| Strength remaining | 60% |
| Safety factor | 1.67 |
| Required BCT | 208 lbf |
| McKee estimate, 32 ECT C flute | 556 lbf |
| Margin | 167% |
How it works
- Load on the bottom box P = (boxes high − 1) × gross weight per box.
- Safety factor SF = 1 ÷ Π(1 − dᵢ) over the losses that apply; parcel shipping uses a floor of 3.
- Required BCT = P × SF, compared with the McKee estimate for your board.
- Default losses are Packgent's assumptions, not sourced values, and every one can be edited.
Results are estimates for planning. Confirm critical packs by test. Full method.
Reading the result
Enter the gross weight of one filled box and the number of boxes in the tallest stack it will see, whether that is on a pallet, in a trailer or in a warehouse rack.
If the required strength is far above any single-wall board, look at the stack before the box: fewer layers, column stacking or keeping boxes on the deck often costs less than a heavier board.
Sources
- 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
- Derating losses: Packgent default assumptions (see /method), pending a primary source
Last reviewed . See all sources and how Packgent computes.