Micron vs S-Count — What’s the Difference?

When selecting natural fibers like wool or cashmere, two measurement systems are commonly used:

1. Micron (μm)
Micron is a scientific measurement of the average diameter of individual fibers. Smaller micron counts equate to finer, softer fibers — a key factor for “next-to-skin” comfort. cashmere.org

2. Spinning Count / S-Count (e.g., 65S, 80S, 100S)
This is a traditional textile grading system that historically referenced how many 560-yard hanks of yarn could be spun from 1 lb of fiber. The higher the S number, the finer and more luxurious the fiber grade. cashmere.org

📌 In modern fiber evaluation, micron is the true physical measure, while S-count is a correlated industry label still widely used in fiber and yarn marketing.

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How Micron Relates to S-Count (General Reference)

Data based on international textile grading and USDA / IWTO correlated standards. cashmere.org

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Why Micron Matters — Softness, Touch & Comfort

Fibers with smaller diameters bend more easily against the skin, resulting in less irritation and a softer handfeel. For example:

• Under ~20 µm – generally soft enough for close-to-skin wear

• ~20–22 µm – still comfortable, slightly more substantial

• Above ~30 µm – often noticeably coarser

This is why fine Merino wool at ~19 µm is widely prized for comfort. cashmere.org

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Understanding Wool S-Counts & Their Uses

100S — Extra Fine Wool

• Fiber: ~≤18.5 µm

• Best for: Soft wearable knits, shawls, baby garments

• Why: Very soft, luxurious feel

90S — Very Fine Wool

• Fiber: ~≤19.5 µm

• Best for: Fine knitwear, refined textured pieces

• Why: Great balance of softness & resilience

80S — Fine Wool

• Fiber: ~17.7–19.1 µm

• Best for: Sweaters, scarves, handspun yarns

• Why: Versatile and forgiving for various crafts

70S — Medium-Fine Wool

• Fiber: ~19.1–20.6 µm

• Best for: Everyday garments, structured knits

• Why: Stronger body with comfortable softness

65S / 64S — Medium Wool

• Fiber: ~20.6–22.6 µm

• Best for: Crafts, outerwear, textured felting

• Why: Substantial fiber often ideal for durable projects

🌟 Note: Medium wool’s slightly coarser nature can make it fun and effective for surface textural crafts like needle felting or punch needle work — not because the standard dictates it, but because the fibers hold shape and texture well in those contexts (practical craft insight). cashmere.org

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Introducing Cashmere — The Luxury Beyond Wool

While sheep wool fibers often range from ~18–30+ microns, cashmere stands apart for its exceptional fineness and softness.

🐐 Cashmere Fiber Characteristics

• Average fiber diameter: typically 14–19 µm 康诗尼+1

• Premium Grade / Ultra-fine: often ≤14.5 µm PandaSilk

• Originates from the soft undercoat of cashmere goats, distinct from coarse guard hairs. cashmere.org

Cashmere fibers are much finer than typical sheep wool, giving them a silky, gentle feel against the skin that is often described as cloud-like. 

Cashmere Quality & Fineness Breakdown

The finer the cashmere fiber, the softer and more luxurious the handfeel — but also rarer and more valuable. 

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Choosing the Right Fiber for Your Projects

✔ Luxury wearables close to skin: Go for higher S-counts (90S–100S) or cashmere with lower micron counts (<16–18 µm)
✔ Everyday knitwear: Mid-range 70S–80S wool balances softness and durability
✔ Textural / durable crafts: 65S / medium wool brings structure and resilience
✔ Ultimate softness: Cashmere ~14–16 µm (superfine / ultrafine)

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Match Fiber to Purpose, Not Just Numbers

Understanding micron and S-count lets you choose fibers with intent — whether you want cloud-soft shawls, structured garments, or unique textured crafts.

With clarity on what these metrics mean in practice, your next spinning, weaving, or knitting project becomes a choice of experience, not guesswork.