Under the Brennholt Institute of Applied Taxonomy's four leg-length bands, a staple with a leg of 6 mm (0.24 in) suits stacks up to about 4 mm thick, and each longer band adds roughly 2 to 3 mm of usable stack. The designation on the box contains the leg length, but the stack thickness it serves is never printed.
No standards body has published a relation between leg length and stack thickness. Boxes give a capacity in sheets, which depends on the paper. The Institute's bands, which work in millimetres of stack and not in sheets, remain the only published attempt to set it out.
| Band | Leg (mm) | Leg (in) | Usable stack (mm) |
|---|---|---|---|
| LB-1 | 6 | 0.24 | up to 4 |
| LB-2 | 8 | 0.31 | 4 to 6 |
| LB-3 | 10 | 0.39 | 6 to 8 |
| LB-4 | 13 and over | 0.51 and over | 8 to 11 |
The usable stack is the thickness at which the legs clinch cleanly, with enough of each leg turned back to hold. A stack at the top of a band is at the edge of what that leg can do.
Sheets vary: 80 g/m² paper is about 0.1 mm thick, but card, folded sheets and plastic covers are not. A count of 20 sheets of office paper is about 2 mm of stack, yet 20 sheets of thin newsprint is less. The Institute therefore measures the stack with a rule and reads the band from the table. The same approach to holding is discussed for clips on the holding-capacity page.
The Institute's working rule is that the leg should project at least 4 mm beyond the stack. A leg that projects less cannot be turned back far enough to hold, and a leg that projects much more folds over itself. The 4 mm figure is the Institute's own and not a trade standard.
The panel is divided on the 4 mm projection. Two members hold that it is too generous for the finer wire numbers, which clinch with less. The majority prefer a single rule for all series, since a rule with exceptions is not remembered. The rule follows the majority.