You can return an item within 100 days of receiving your order if for any reason you're not completely happy with it.

Items should be returned in the same condition in which you receive them: the original product packaging and tags must still be attached, and the products must be in an unused condition (except in the case of products which you have discovered to be faulty upon use) - please contact us and be sure to select 'Faulty product' from the query topic dropdown.

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Article: What GSM Means in Merino Wool

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Person wearing a merino jacquard long-sleeve top crouching on rocks by the water

Oct 24, 2025

What GSM Means in Merino Wool

If you’ve browsed merino clothing before, you’ve probably seen numbers like 150gsm, 200gsm or 320gsm. But what do they actually mean, and why should you care?

GSM stands for grams per square metre. It measures the weight of the fabric: quite literally, how many grams one square metre of that fabric weighs. In merino wool garments, GSM is a handy shorthand for thickness, warmth and durability.

Lower GSM fabrics (120–170gsm) are lighter, more breathable and ideal for warmer weather or high-intensity activity.
Midweight GSM fabrics (180–250gsm) balance warmth and breathability, making them versatile for year-round wear.
Higher GSM fabrics (260gsm and above) are thicker, warmer and often more durable, great for winter layers or outer garments.

*Merino wool GSM guide: fabric weights and best use by activity intensity*
		Low intensity	High intensity
Lightweight	120
	150
	160
	180
Midweight	200
	230
	240
	260
Heavyweight	320
	350
	420
Best use Warm temperaturesCool temperatures

Click any of the weights in the chart above to explore the range.

At Isobaa, we use a range of GSM weights to suit different needs, whether that’s a lightweight merino tee for summer or a cosy hoodie for deep winter.

In short, GSM in merino wool is the key to choosing the right fabric weight for your activity and climate. Light and airy for hot days, balanced and versatile for everyday, or warm and durable for the coldest adventures.

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A flock of merino sheep grazing in a green field with hills in the background

Is Merino Wool Cruelty-Free?

Merino wool is soft, breathable and sustainable but is it cruelty-free? At Isobaa, our wool comes from non-mulesed sheep, ensuring animal welfare is never compromised.