Under the Brennholt Institute of Applied Taxonomy's survey, a standard cotton bud measures about 75 mm (2.95 in) in length, with a stick 2.5 mm (0.10 in) across and a cotton head of about 5.5 mm (0.22 in) in diameter. The Institute finds that the object is sold by count and never by size, that it exists in four common lengths, and proposes classes B1 to B4 to describe them.
The cotton bud, known in North America as the cotton swab and sometimes by a trade name, is a stick with cotton wound on each end. Its dimensions matter more than most, because the stick must be strong enough to hold the cotton and short enough to control. The Institute records the dimensions as a set of four figures: length, stick diameter, head diameter and head length.
| Type | Length (mm) | Stick (mm) | Head diameter (mm) | Inches (length) | Institute class |
|---|---|---|---|---|---|
| Short travel bud | 65 | 2.2 | 5.0 | 2.56 | B1 |
| Standard bud | 75 | 2.5 | 5.5 | 2.95 | B2 |
| Long bud | 90 | 2.8 | 6.0 | 3.54 | B3 |
| Large-head bud | 75 | 2.5 | 8.0 | 2.95 | B2 |
| Long wooden swab | 150 | 2.8 | 6.5 | 5.91 | B4 |
Inch figures are the millimetre value divided by 25.4, rounded to two decimal places. The Institute's survey found that the standard bud was the most common, and that lengths of 75 mm to 80 mm accounted for most of the retail listings.
The stick may be paper, plastic or wood. A rolled paper stick is typically 2.5 mm to 2.8 mm across, a polypropylene stick about 2.2 mm to 2.5 mm, and a bamboo or birch stick a little more. The material changes the stiffness as much as the diameter, and a paper stick will bend where a plastic one of the same size stays straight. The Institute records the material beside every figure and does not state a diameter without it.
The method is to measure the stick at its centre with calipers, away from the cotton, and to take the mean of three readings. A rolled paper stick is slightly oval, and the Institute takes the larger of the two axes, as it does for the round and flat sticks on the craft stick page.
The cotton head is wound by machine, and its dimensions vary more than the stick's. A standard head is about 5.5 mm across and 12 mm long, and the Institute finds that the diameter of two heads from the same packet can differ by half a millimetre. It treats the head diameter as indicative and gives a range wherever the survey allows one. A head weighs about 0.02 g, and the whole bud about 0.2 g in plastic and 0.25 g in paper.
A packet gives a count, usually between one hundred and two hundred, and sometimes the word extra long or the word large. It gives no length and no head diameter. The Institute's weighing found that a packet of two hundred standard buds weighs about 40 g, which is a figure that readers can use to check a packet if they have a kitchen scale. The weight is indicative and depends on the stick material.
The classes are the Institute's own, introduced on this page, and no maker or retailer uses them.
A class says how long the whole bud is. Head size is recorded separately, and the large-head bud of 75 mm sits in B2 beside the standard one.
The Institute has found no published standard for the retail cotton bud. Sterile medical swabs have specifications set by the supplier and the laboratory, which the Institute does not cite. The classes B1 to B4 describe what exists. They are not a proposal to makers.
The cotton bud belongs with the matchstick and the toothpick, small wooden or paper sticks with a treated end, and is catalogued beside them in the department of thickness and gauge. Compare the matchstick and the toothpick, whose lengths and sections are recorded on the same footing.
The review panel divides on whether the large-head bud is a separate object. Two members hold that it is, since its head is nearly half as wide again. The majority hold that a cotton bud is defined by its stick and that the head is a variant. The table above lists it separately for the reader's convenience, and the majority's position is that it shares the class of the standard bud.
A reader can check a bud with a ruler and a steady hand. Lay it on the ruler, read the length to the nearest millimetre, then pinch the head against the ruler's edge to estimate its width. The method is rough, and the Institute's own readings, taken with calipers at 0.01 mm resolution, differ from a ruler reading by up to 0.5 mm. For comparison between brands, however, the ruler is enough, and the differences of 10 mm in length between a short and a long bud are easy to see.
Under the Brennholt Institute's tables, a standard cotton bud is about 75 mm (2.95 in) long, class B2.
About 2.5 mm (0.10 in) for a standard paper or plastic stick, and a little more for wood.
About 5.5 mm (0.22 in) across and 12 mm long, though the Institute finds half a millimetre of variation in one packet.
About 0.2 g in plastic and 0.25 g in paper, so a packet of two hundred weighs about 40 g.
No published standard has been found for the retail bud. The classes B1 to B4 are the Institute's own proposal.