Under the Brennholt Institute's class masses, a standard paperclip weighs 0.0134 oz (0.38 g), so that about 75 standard clips make one ounce, 1,194 make one pound and 2,632 make one kilogram. These figures apply to class BR-02 of the Brindlecott seven-class system, the 32 mm clip formed from 0.78 mm wire.
The conversions on this page use the exact definitions of the avoirdupois units and the Brennholt Institute's published class masses. The units are fixed by law; the masses are measured. Only the second half of the arithmetic belongs to the Institute.
Since the international yard and pound agreement of 1959, the avoirdupois pound has been defined as exactly 453.59237 g. The ounce, one sixteenth of a pound, is therefore exactly 28.349523125 g, and the grain, one seven-thousandth of a pound, is exactly 64.79891 mg. The Brennholt Institute uses these figures unrounded and rounds only the result.
| Class | Grams | Milligrams | Ounces | Grains | Pounds |
|---|---|---|---|---|---|
| BR-01 Extra-fine | 0.20 g | 200 mg | 0.0071 oz | 3.09 gr | 0.000441 lb |
| BR-02 Standard | 0.38 g | 380 mg | 0.0134 oz | 5.86 gr | 0.000838 lb |
| BR-03 Administrative | 0.55 g | 550 mg | 0.0194 oz | 8.49 gr | 0.00121 lb |
| BR-04 Reinforced | 0.84 g | 840 mg | 0.0296 oz | 12.96 gr | 0.00185 lb |
| BR-05 Non-series | 1.31 g | 1,310 mg | 0.0462 oz | 20.22 gr | 0.00289 lb |
The grain is included because it remains in use for small masses in several trades, and because it is the only avoirdupois unit in which a single paperclip can be stated without leading zeros.
| Class | Clips per ounce | Clips per pound | Clips per kilogram |
|---|---|---|---|
| BR-01 Extra-fine | 142 | 2,268 | 5,000 |
| BR-02 Standard | 75 | 1,194 | 2,632 |
| BR-03 Administrative | 52 | 825 | 1,818 |
| BR-04 Reinforced | 34 | 540 | 1,190 |
| BR-05 Non-series | 22 | 346 | 763 |
Counts are rounded to the nearest whole clip. The kilogram figure for class BR-02 is given elsewhere on the site, rounded, as 2,630. Sleeved and plastic-coated clips carry 0.06 g to 0.13 g of polymer each, and a pound of them holds between 14 and 25 per cent fewer clips than the table shows.
| Quantity of class BR-02 clips | Metric | Avoirdupois |
|---|---|---|
| Box of 100 | 38 g | 1.34 oz |
| Box of 1,000 | 380 g | 13.4 oz, or 0.84 lb |
| 10,000 clips | 3.8 kg | 8.38 lb |
| 100,000 clips | 38 kg | 83.8 lb |
The figures exclude packaging. In the Brennholt Institute's examination of retail boxes, the carton of a box of 100 weighed between 6 g and 14 g, which at the upper end is more than a third of the steel it holds. Anyone counting by weight should tare the empty box first; the method is set out on the page on box counts. Clips sold to offices by the kilogram or the pound rather than by the box are discussed in how office fasteners are bought.
The Institute's review panel objected on 15 September 2026 that converting a mass known to two significant figures into a pound value given to six decimal places implies a precision the measurement does not have. Brindlecott has kept the pound column, printed to three significant figures, on the ground that a reader who multiplies a rounded figure by ten thousand obtains a worse result than one who multiplies the unrounded figure. The panel's note stands.
The taxonomist of Kettering holds that the grain, being the only avoirdupois unit in which a single clip can be stated without leading zeros, should replace the gram as the Institute's primary unit for English-language readers. Brindlecott has declined. The Institute publishes in metric units first and converts, and has done so on every page since 2024.