Merino wool is a very fine, soft wool from Merino sheep. It is warm, breathable, moisture-wicking and naturally odour resistant, which is why it is used for base layers, socks and outdoor clothing. This guide explains what makes merino different from ordinary wool, how the weights work and how to look after it.
Last updated November 2026.
What is merino wool?
Merino is the wool from Merino sheep, a breed known for exceptionally fine fleece. Because the fibres are so fine, merino feels soft against the skin and is much less itchy than traditional coarse wool.
Why is merino wool so good for outdoor clothing?
- Warm: Wool fibres trap air, which insulates you in the cold.
- Breathable: Merino moves moisture vapour away from your skin so you feel less clammy.
- Temperature regulating: It helps keep you comfortable in a range of temperatures, not just the cold.
- Odour resistant: It stays fresher for longer than most synthetic fabrics, so you can wear it for several days between washes.
- Warm when damp: Wool keeps insulating even when it is slightly wet.
- Soft: Fine fibres feel comfortable next to the skin.
What do merino weights like 150 and 200 mean?
Merino garments are often named after the fabric weight in grams per square metre. A higher number means a thicker, warmer fabric.
- 150: A lightweight fabric for warm days and active use. The Icebreaker Merino 150 Tech Lite t-shirt is an example.
- 200: A midweight fabric for cooler weather, such as the Icebreaker Women's Merino 200 Oasis thermal top.
Our Icebreaker base layer guide explains the full range.
What is a merino base layer?
A base layer is the layer next to your skin. A merino base layer wicks sweat, adds warmth and fits closely. Wear it under a fleece or jacket for hill walking, shooting or cold days outdoors. Read our layering guide for how to put the layers together.
Merino vs synthetic base layers
Synthetics dry quickly and are often cheaper and more hard-wearing. Merino is softer, handles odour better and stays comfortable across a wider range of temperatures. Many people wear merino for multi-day trips and synthetics for fast, sweaty activities.
Merino socks
Merino socks cushion, wick moisture and resist odour. Look at Smartwool Hike socks and Hoggs of Fife 1903 merino socks. Our best walking socks UK guide compares them.
How to care for merino wool
Wash on a gentle or wool cycle at a cool temperature with a wool-safe detergent, skip the fabric softener and dry flat. See our full guide on how to wash merino wool.
Merino wool FAQs
Is merino wool itchy?
Fine merino fibres are much softer than traditional wool, so most people find merino comfortable against the skin. Sensitivity varies from person to person.
Is merino wool warm?
Yes. It traps air to insulate you, and the thickness depends on the fabric weight.
Does merino wool smell?
Much less than many synthetic fabrics, which is why merino is popular for travel and multi-day walks.
Is merino wool waterproof?
No. It is breathable and stays warm when damp, but it is not waterproof. Wear it as a base or mid layer under a waterproof jacket.
Can you machine wash merino wool?
Many merino garments can be machine washed on a gentle cycle. Always follow the care label.
Shop merino
Browse Icebreaker merino and Smartwool. More guides are in The Field Guide.
Need help choosing?
Not sure which merino is right? Email help@4elementsclothing.co.uk and we will be happy to help. Orders placed before 3pm Monday to Friday (10am Saturday) are dispatched the same day.
