The Brennholt Institute of Applied Taxonomy records treasury tags in five lengths, 51 mm, 76 mm, 102 mm, 127 mm and 152 mm (2, 3, 4, 5 and 6 in), measured from tip to tip of the metal ends with the cord drawn straight. The tag's length is the length of its cord, and the length sets how thick a stack it will hold: the Institute's working rule is that a tag will gather a stack about one-eighth of its length in thickness.
A treasury tag is a length of cord or ribbon with a rigid metal tip at each end. The tips are passed through a hole in the stack of paper and tied or joined. The Institute has found no published standard for its dimensions, and its figures are its own.
| Length (in) | Length (mm) | Stack it gathers (mm) | Approx. sheets, 80 gsm |
|---|---|---|---|
| 2 | 51 | 6 | 60 |
| 3 | 76 | 9 | 90 |
| 4 | 102 | 13 | 130 |
| 5 | 127 | 16 | 160 |
| 6 | 152 | 19 | 190 |
The figure for sheets assumes paper of 80 gsm, in which 100 sheets stack to about 10 mm. The Institute adds a 20 per cent allowance because the tag has to close with slack, and so the stated capacities are conservative. They are the Institute's calculations from its own rule, not manufacturers' figures.
The Institute's survey of 12 retail packs in 2025 found tip lengths of 19 mm to 24 mm, and cord diameters of 1.6 mm to 2.4 mm. Of the 12 packs, eight were sold in assorted lengths and four in a single length.
The Institute offers a scheme of three classes, by length. It is the Institute's own and is not a trade standard.
Of the 12 packs, five held T1 tags, nine held T2, and four held T3, with some packs holding more than one class. The Institute notes that the 102 mm tag is the commonest single length.
The Institute makes no claim about the origin of the name. It is generally attributed to British government offices, and the Institute has found no dated source for the attribution, so it does not repeat a date. The tag's materials, brass-plated steel and cotton, require no discussion here, and the metal's plating is considered on the plating page.
The panel is split on whether the length should be measured with the tips included or on the cord alone. Including the tips gives a figure about 40 mm greater. The majority include them, since a user can see the whole tag, but two members hold that the cord alone governs capacity. The table uses the whole length, and the capacity column was calculated on that basis.
Where a tag is too bulky, the alternative is a paper fastener, treated on the paper fastener page, or a clip, treated on the binder clip page. The Institute reminds readers that its classes are a convenience and that none of its figures is a standard.