Super S numbers

In detail

The designation is tied to mean fiber diameter in microns, the property that most affects how soft wool feels against skin and how fine a yarn it can make. A Super number is attached to a fabric, not to a sheep, and in principle describes the wool that went into it. Industry codes of practice and, in some jurisdictions, labeling rules link each Super number to a maximum mean diameter and set conditions on its use. Because the current official table could not be checked for this edition, specific micron values are deliberately not given here.

The science and numbers

Wool fineness is measured as mean fiber diameter in microns on a fiber sample, usually with a distribution around the mean; the standard deviation or coefficient of variation matters for handle and prickle. Finer fibers allow more fibers in a yarn cross-section at a given linear density, which permits finer, smoother yarns and lighter cloth. That is the physical reason Super numbers rise as microns fall. Verification requires laboratory measurement of fiber diameter on fibers taken from the fabric or its yarns, compared against the diameter limits in the governing code or regulation. A buyer who needs certainty should request test results rather than rely on the woven selvedge mark.

A practical example

Two navy suitings are labeled Super 110s and Super 150s. A buyer expects the second to use finer wool and to feel smoother. The buyer should also expect the finer fabric to be lighter and potentially less resistant to abrasion and creasing. The label says nothing about the weave, yarn twist, finishing or whether the fabric suits daily wear.

What to distinguish

A Super number describes fiber fineness only. It does not certify origin, animal welfare, farming method, dyeing quality or durability; very fine fabrics can be more delicate. Whether a Super claim may legally appear, and under what conditions, is a jurisdiction-specific question; in the United States, check the current text of the Wool Products Labeling Act and FTC rules rather than a supplier's summary.

Origins and history

Super numbers are generally described as descending from the older worsted quality-number tradition, in which finer wool could be spun into higher counts. Over time the number came to be read as a fineness grade rather than an achievable spinning count, and the need for consistency led industry bodies and regulators to define the term. This edition could not confirm the dates and wording of those definitions, so it states the history qualitatively.

Related terms

• Micron
• Worsted
• Wool Products Labeling Act
• Top
• Greasy wool

Sources & further reading

• Woolmark: What is the wool fibre?
• International Wool Textile Organisation: First-stage processing

Technical references reviewed 2026-09-22. Examples are illustrative. Industry organizations and manufacturers describe their own fields; their references are not independent product endorsements. Figures are approximate and depend on the stated test conditions.