What is a micron and why should it matter to you?
- Melanie
- May 14, 2025
- 3 min read
If you’ve ever wondered why some wool feels softer than others, the secret is in the micron. Whether you’re new to knitting or just curious about your favourite yarn, understanding microns will help you make better choices, especially when selecting fibres for skin-sensitive projects.
Let’s dive into what a micron is, and why it matters when choosing wool for your next creation!
What Is a Micron and Why Should It Matter to You?
A micron, short for micrometer, is a unit of measurement used to describe the diameter (the distance from one side to the opposite side of a circle, measured by a line passing through the centre of the circle) of a single fibre.
µ or µm is the symbol for micron
1 micron = one-millionth of a metre
For reference, a human hair is about 50–100 microns wide.
Microns measure the diameter of the fibre - the lower the micron number, the softer the yarn.
In other words, in the fibre world, the smaller the micron number, the finer and softer the fibre feels. So, a lower micron count means the wool feels smoother and gentler against your skin.
🌟 Why Micron Count Matters
In the fibre world, the smaller the micron number, the finer and softer the fibre feels against your skin:
<18 microns – ultra soft (great for baby garments, next-to-skin wear)
18–22 microns – soft and comfortable (perfect for sweaters, hats, and scarves)
23–30 microns – slightly coarser (can still be soft but may feel prickly to sensitive skin)
>30 microns – generally felt as rough or scratchy, often used for durable items like rugs or outerwear.
🐑 Where Does Merino Fit In?
Merino wool stands out because of its extremely fine micron count—usually between 17 and 21 microns. This gives it its incredibly soft, smooth texture that doesn’t irritate the skin, making it perfect for those with sensitive skin or allergies to coarser wools.
Unlike traditional wool, which can feel itchy or scratchy, Merino wool feels light and breezy, yet provides excellent warmth. It’s the ideal choice for projects like:
Socks: Soft enough to wear all day long without irritation.
Baby clothes: Non-irritating and safe for delicate skin.
Scarves and shawls: Luxurious to wear without the discomfort.
💡 The Science Behind Merino’s Softness
Merino wool fibres are naturally crimped, meaning they have a slight wave to them. This gives them a springy, buoyant texture that makes the wool feel softer and warmer. The crimp also helps Merino wool to trap heat while remaining breathable, so it keeps you cozy without making you overheat.
Plus, Merino’s finer fibres mean it’s often considered hypoallergenic, and it has the ability to wick moisture away from the skin, keeping you dry and comfortable.
🌱 Perfect for Sensitive Skin Projects
Merino wool’s fine structure and softness make it the go-to fibre for anyone with skin sensitivities. Whether you’re knitting for babies, people with sensitive skin, or even yourself, choosing Merino means you’re selecting a fibre that won’t itch or scratch. Plus, it’s machine washable (if you choose super wash Merino)—making it a practical, low-maintenance option for everyday wear.
Why Should You Choose Merino for Your Next Project?
There are so many great reasons to choose merino, here are but a few:
Softness: Merino wool’s fine fibres make it gentle on the skin.
Breathability: Helps regulate body temperature by keeping you warm without overheating.
Versatility: Great for a wide range of projects, from lightweight shawls to cozy sweaters.
Durability: It can withstand wear while remaining smooth and comfortable.
Eco-friendly: It’s biodegradable and sustainable, making it a great natural choice for conscientious knitters.
So, next time you’re shopping for yarn, check the micron count to see what kind of texture and feel you can expect. For projects that require softness, comfort, and warmth, Merino wool should always be a top contender! Is it already your go to fibre, or do you have another favourite? Please, get the conversation started in the comments below!