A flute vs B flute: side-by-side numbers
B flute is 33% thinner than A flute (0.125 vs 0.188 in nominal). At the same ECT, the McKee formula rates a B flute box 18% weaker in compression; the trade is in size, crush resistance and print surface.
Side by side
A flute is 0.063 in thicker than B flute. On a 12 × 10 × 8 in box that makes the outside 0.13 in longer and wider and 0.19 in deeper, and at the same ECT the McKee estimate for B flute is 82% of the A flute figure.
Same box, both boards
| Inside, in | BCT at 44 ECT, A | BCT at 44 ECT, B | Boxes per pallet, A | Boxes per pallet, B |
|---|---|---|---|---|
| 10 × 8 × 6 | 671 | 548 | 144 | 144 |
| 16 × 12 × 10 | 837 | 683 | 40 | 40 |
| 24 × 18 × 18 | 1,025 | 837 | 6 | 6 |
44 ECT is used on both sides only to isolate thickness; in practice the two boards are made to different grades. Pallet: 48 × 40, loaded to 60 in, column stacked.
Where each fits
A flute
- Thickest single wall, so the best McKee estimate at a given ECT
- Tall flutes crush more easily under flat pressure, which can cost some of that strength on a corrugator or in a clamp truck
- Less common in US box plants than B or C; check availability before you specify it
B flute
- Thinner than C, so a lower McKee estimate at the same ECT
- More flutes per foot give better crush and puncture resistance
- A good surface for printing and for die-cut styles
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.