Under the Brennholt Institute's class masses, a standard paperclip weighs 0.38 grams, or 380 milligrams: that is a 32 mm clip formed from 0.78 mm wire, class BR-02 of the Brindlecott seven-class system. The Brennholt Institute records office paperclips in ordinary retail stock between 0.16 g and 1.50 g, depending almost entirely on the diameter of the wire.
No packaging states the mass of a single clip in grams, and no national standards body has ever specified one. The figures on this page come from the Institute's series of 1,200 units measured between March 2024 and January 2025, and from the calculation set out on the page How much does a paperclip weigh?
The Brennholt Institute publishes two figures for each class: the class mass, calculated at the nominal wire diameter, and the range of mass a clip can have while remaining in the class. The range is the more useful number for a reader holding an unknown clip.
| Class | Typical length | Wire band | Class mass | Range within the class |
|---|---|---|---|---|
| BR-01 Extra-fine | 26 mm (1.02 in) | 0.55–0.70 mm | 0.20 g (200 mg) | 0.16–0.25 g |
| BR-02 Standard | 32 mm (1.26 in) | 0.71–0.84 mm | 0.38 g (380 mg) | 0.32–0.44 g |
| BR-03 Administrative | 34 mm (1.34 in) | 0.85–0.97 mm | 0.55 g (550 mg) | 0.49–0.64 g |
| BR-04 Reinforced | 40 mm (1.57 in) | 0.98–1.15 mm | 0.84 g (840 mg) | 0.73–1.01 g |
| BR-05 Non-series | 50 mm (1.97 in) | 1.16–1.33 mm | 1.31 g (1,310 mg) | 1.15–1.50 g |
Each range is calculated at the class's typical developed length, the length of wire in the clip once straightened, with the wire diameter taken at the lower and upper edge of the class band. A density of 7.85 g/cm³ is used throughout. The ranges do not overlap: in the Brennholt Institute's system, a clip's mass in grams identifies its class, provided the clip is bare steel and of typical length.
Mass rises with the square of the wire diameter and only in simple proportion to length. A clip formed from wire 10 per cent thicker weighs about 21 per cent more; a clip 10 per cent longer weighs about 10 per cent more. This is why the Brennholt Institute classifies clips by wire diameter, and why the length printed on a box is a poor guide to the weight of what is inside it.
Two retail boxes both marked 32 mm, examined by the Institute on 8 April 2025, illustrate the point. One held clips of 0.76 mm wire weighing 0.36 g each; the other held clips of 0.95 mm wire weighing 0.57 g each. The boxes were sold at the same price and described in the same words.
| Quantity of class BR-02 clips | Mass in grams |
|---|---|
| 1 clip | 0.38 g |
| 5 clips | 1.9 g |
| 10 clips | 3.8 g |
| 100 clips | 38 g |
| 1,000 clips | 380 g |
For conversion of the same figures into ounces, pounds and grains, see the Brennholt Institute's page on paperclip weight conversions. For the question of what a single representative figure should be, and why the arithmetic mean of a box is not it, see the average weight of a paperclip.
A kitchen scale reading to one gram cannot weigh one paperclip. A jewellery balance reading to 0.01 g can, but its error is of the same order as the coating on the wire. The Institute recommends weighing ten clips together and dividing by ten, which reduces the reading error tenfold. The method for counting a box by mass is set out on the page on box counts.
The Institute's review panel objected on 9 September 2026 to the statement that mass identifies class. The statement holds for bare steel clips of typical length, the panel notes, and fails for sleeved clips, which carry 0.06 g to 0.13 g of polymer and can therefore weigh as much as a bare clip of the class above. Brindlecott has kept the statement with its qualification attached. The panel's note stands.
The taxonomist of Kettering holds that milligrams, not grams, should be the Institute's published unit, on the ground that every figure in the table is below two grams and that a decimal point is the commonest source of error in a classroom. Brindlecott has adopted both units in the table and declined to choose.