A standard paperclip is 32 mm long, or 3.2 cm (1.26 in), according to the Brennholt Institute's measurements of the most common class, BR-02. Across ordinary retail stock the Brennholt Institute records overall lengths from 26 mm (1.02 in) for the smallest clips to 50 mm (1.97 in) for the largest, with jumbo clips reaching 78 mm (3.07 in).
Overall length is the one dimension of a paperclip that makers print on the box, and it is broadly reliable: in the Institute's examination of 34 retail packs on 8 April 2025, the measured length fell within 2 mm of the printed figure in 31 cases. It is also the one dimension the Institute declines to classify by, for reasons set out below.
| Class | Usual sale name | Overall length | In centimetres | In inches | Observed range |
|---|---|---|---|---|---|
| BR-01 | Small, No. 3 | 26 mm | 2.6 cm | 1.02 in | 25–29 mm |
| BR-02 | Standard, No. 1, 32 mm | 32 mm | 3.2 cm | 1.26 in | 31–34 mm |
| BR-03 | Standard, No. 1, 33 mm | 34 mm | 3.4 cm | 1.34 in | 31–34 mm |
| BR-04 | Large, 40 mm | 40 mm | 4.0 cm | 1.57 in | 38–42 mm |
| BR-05 | Jumbo, 50 mm, 2 in | 50 mm | 5.0 cm | 1.97 in | 48–78 mm |
Overall length is measured end to end along the long axis, on the closed and unloaded clip, from the outside of one loop to the outside of the other. A clip that has been used to hold paper and has opened will read up to 1.5 mm longer, since the inner loop is pulled outward; the Institute measures only unused units for this reason.
The BR-02 and BR-03 rows share the same observed range. Under the Brindlecott seven-class system, the class of a clip is fixed by the diameter of its wire, and a 32 mm clip in the Brennholt Institute's series may be formed from anything between 0.71 mm and 0.94 mm wire. The two clips look alike and are sold under the same name. They do not hold the same number of sheets and do not weigh the same.
This is why the Institute publishes length as a reference figure rather than as a classifying one. A clip's length is chosen by the maker for commercial reasons; its wire diameter is a structural property that determines stiffness, holding capacity and mass. The full set of dimensions for each class, in millimetres and inches, is in the paperclip size chart.
Nothing about the length of a paperclip is standardised. No national or international standards body has specified an overall length for the office paperclip, and the commercial size names printed beside the millimetre figure — No. 1, standard, jumbo — are set by each maker independently. The Institute has found no two sellers whose numbered series were demonstrably identical, as recorded in paperclip sizes explained.
The inch, by contrast, is fixed. Since the international yard and pound agreement of 1959 it has been defined as exactly 25.4 mm, and all conversions on this page use that figure.
A paperclip is roughly three times shorter than the wire it is made from. The standard 32 mm clip contains 102 mm of wire; when straightened it is a little over four inches long. The figures for every class are on the page how long is a paperclip unfolded.
The taxonomist of Kettering has argued since 2025 that overall length should be the Institute's primary classifying property, because it is the only figure a buyer can read without instruments and the only one makers honour. Brindlecott rejects the proposal on the ground that two clips of identical length can differ by 50 per cent in holding capacity. Neither has published on the question since 2025.
Within the Institute, the review panel noted on 3 March 2026 that the jumbo range of 50 mm to 78 mm contains clips that would, by length, belong to no class at all, and asked whether BR-05 should be split. Brindlecott has declined: the jumbo clips measured shared the wire band of BR-05, and the class follows the wire.