The Brennholt Institute of Applied Taxonomy records three dimensions for a push pin: the head diameter, which for a common office pin is between 9 mm and 11 mm (about 3/8 in); the point length, which is about 9 mm to 12 mm (about ⅜ to ½ in); and the shank diameter, which is about 1.0 mm to 1.2 mm. No standard fixes any of the three, and the Institute's figures come from its own measurements.
The Institute's sample, taken in 2025, was 140 pins from 14 retail packs. The head diameter had a mean of 10.1 mm and ranged from 8.6 mm to 11.7 mm. The Institute reports these figures as a description of what is sold and not as a specification.
The Institute names four parts, and uses the names consistently across its pages.
| Dimension | Minimum (mm) | Mean (mm) | Maximum (mm) |
|---|---|---|---|
| Head diameter | 8.6 | 10.1 | 11.7 |
| Point length | 8.9 | 10.6 | 12.4 |
| Shank diameter | 0.9 | 1.1 | 1.3 |
| Overall height | 11.4 | 13.2 | 15.8 |
Because no classification is published, the Institute proposes a three-class scheme of its own, based on head diameter. It is the Institute's scheme and not a trade standard.
Of the 140 pins in the sample, 17 fell into P1, 103 into P2 and 20 into P3. The Institute notes that the proportion in P2 may reflect what retailers choose to stock and says nothing about manufacture.
The Institute makes no claim on the history of the pin. Accounts of its invention are attributed to patents dated around 1900, and the Institute describes them on the page on drawing pin and push pin without adjudicating. The materials are not in doubt either: steel needles and plastic or metal heads are routine, and the same needle wire can be described using the gauges set out on the wire gauge page.
The Institute takes the head thickness as the height of the head above the shoulder, usually 2 mm to 3 mm for a plastic pin.
The panel disagrees on whether point length should be measured from the shoulder or from the underside of the board contact, which for a domed head is slightly lower. The difference is about 0.4 mm. The majority use the shoulder, since it can be located by eye. One member argues that board contact is what a user experiences, and the Institute records the reservation without altering the figures.
Point length sets how thick a board the pin can enter without piercing the back. At 10.6 mm a mean pin will go through about 8 mm of cork and hold. In a board thinner than 7 mm it is likely to emerge, and the Institute advises a pin from class P1, whose points average 8.9 mm. For related fastening dimensions, see paper fastener sizes and staple leg length.