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Wool S-number

Scabal | Wool Fabrics
Super S numbers list

An S number on the label of wool suits or other tailored garments, woolen fabrics or yarns indicates the fineness of the wool fiber used in making the garments, measured by the maximum diameter in micrometers.


Fiber fineness is one of the factors that determine the quality and performance of a wool product. A higher super number will mean that a fabric is going to be softer and finer to the touch and generally will feel more like luxurious. Wool with lower Super Numbers will usually feel coarser.

A higher super number does to some extent denote the exclusivity of a given fabric, because something like a super 200s would contain some of the rarest wool fibers available, this is only an indication of that exclusivity and rarity, not necessarily subjective quality.

Scabal - Wool Fabrics

As now used Super means pure new wool and can also be used for fabrics made from wool blended with rare fiber (such as mohair, cashmere wool and alpaca), and also with silk. 


The inclusion of Elastane to give the fabric a stretch effect is permitted, as also is the inclusion of up to 5% non-wool yarn for decorative effects. 

For wool blend fabric descriptions, the word Super is not permitted. Subject to the wool content being at least 45%, the S number may be used.


The S-number indicates the thickness of the fiber as defined in the IWTO Super S Code of Practice. Each S-number correlates to a maximum fiber diameter measured in micrometers, as shown in the table below. Fiber diameters are measured from the finished, dyed fabric.

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