C flute vs E flute: side-by-side numbers
E flute is 60% thinner than C flute (0.063 vs 0.156 in nominal). At the same ECT, the McKee formula rates a E flute box 37% weaker in compression; the trade is in size, crush resistance and print surface.
Side by side
C flute is 0.094 in thicker than E flute. On a 12 × 10 × 8 in box that makes the outside 0.19 in longer and wider and 0.28 in deeper, and at the same ECT the McKee estimate for E flute is 63% of the C flute figure.
Same box, both boards
| Inside, in | BCT at 44 ECT, C | BCT at 44 ECT, E | Boxes per pallet, C | Boxes per pallet, E |
|---|---|---|---|---|
| 10 × 8 × 6 | 613 | 387 | 144 | 144 |
| 16 × 12 × 10 | 764 | 483 | 40 | 40 |
| 24 × 18 × 18 | 936 | 592 | 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
C flute
- Thicker than B, so stronger in McKee at the same ECT
- Fewer flutes per foot than B, so slightly less crush and puncture resistance
- Print surface is fine for simple marks; fine graphics prefer finer flutes
E flute
- Thin, so stacking strength is low; McKee drops with the square root of caliper
- Many flutes per foot give a flat surface and good crush resistance
- Saves space: more boxes per pallet of flat stock, smaller outside dimensions
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.