What GSM Should a Wool Quilt Be? An Honest Guide

For most Australian bedrooms, 300 to 450 GSM covers the year. Under 300 is a summer weight, 450 and above is for genuinely cold winters, and in Queensland or the Northern Territory a 200 GSM quilt will do all twelve months.

That is the short answer and it is the one everyone gives you. The longer answer is that GSM measures how much wool is in a quilt, not how warm it is, and the difference between those two things is where most disappointing quilt purchases come from.

What GSM actually measures

GSM stands for grams per square metre. Weigh one square metre of the filling, and that is the number.

A 350 GSM queen quilt contains 350 grams of wool for every square metre of its surface, so a little over 1.5 kilograms of wool across the whole thing.

It is a measure of mass. Not warmth, not loft, not how evenly the filling is spread, and not how any of that will look in five years. It became the standard in Australia because it is easy to measure and easy to print on a label, not because it is the most useful thing to know.

The Australian GSM guide

Every major Australian wool quilt brand publishes roughly the same chart, and they agree closely enough that it is worth treating as settled.

Climate changes this more than anything else. Halcyon Dreams, who sell the full range from 200 to 700, note that their 350 GSM quilt is used as a winter quilt by customers in Brisbane and further north, and that even their 200 GSM is used as a winter and off-season quilt in tropical areas, Western Australia and the Northern Territory.

So there is no universal right answer. A 350 GSM quilt is an autumn quilt in Hobart and a winter quilt in Cairns.

Why two quilts at the same GSM can feel completely different

Here is where the number stops being useful, and the interesting thing is that the industry says so itself.

Supreme Quilts: a 500 GSM quilt made from high fill-power goose down might outperform a 600 GSM quilt filled with lower-grade feathers.

Best Quilt Australia: GSM doesn't tell the whole story, and a 350 GSM wool quilt will typically feel warmer than a 350 GSM microfibre quilt.

Sienna Living: two quilts with the same GSM can feel completely different.

All three are right, and all three stop at the same place. They explain that the fibre changes what a GSM figure means. None of them mentions that the construction changes it just as much.

Warmth does not come from the wool. It comes from the air trapped between the fibres. So the questions that actually matter are how much air that wool holds, whether it holds it evenly across the whole quilt, and whether it will still be doing both in year five.

GSM answers none of them.

Loose fill against a bonded sheet

Almost every wool quilt on the market is made one of two ways.

Loose carded wool. The wool is opened and carded into a fluffy batt, laid into the casing, and quilted into channels or pockets. The stitching exists for one reason: to stop loose wool moving. It is a containment system.

A bonded sheet. The wool is needle-punched into a single continuous web before it ever goes into a quilt. Millions of barbed needles are driven through stacked layers of fleece, dragging fibres vertically until they lock into one another. What comes out is a sheet of wool that holds its own shape, with no glue, no resin and no synthetic binder.

The difference matters on day one and matters more every year after.

Loose fill settles. It drifts toward the foot of the bed, gathers in the corners of its channels, and thins out in the middle. A quilt that started at an even 500 GSM ends up at 700 in some places and 300 in others, and a thin patch is a cold patch no matter what the label said. This is the most common complaint about wool quilts that were perfectly good when new.

A bonded sheet cannot do that. There is nothing loose inside it to move.

So the GSM figure on a needle-punched quilt describes what you will actually have in year five. The same figure on a loose-filled quilt describes what you had on the day it was made.

Interestingly, Supreme Quilts gets close to this without following it through, noting that wool quilts are specified by GSM rather than fill weight because the filling is a large sheet of wadding. That is precisely what needle-punched blanketing is.

What happens in year five

There is a test for this. Not for quilts specifically, but for the material.

Under EN ISO 3385, a weighted foot is dropped onto a sample 80,000 times, and the sample is then left six hours to recover and measured to see how much thickness it has lost for good. Furniture makers use it to find out whether a cushion will sag in three years without waiting three years.

Wisewool had its needle-punched wool tested this way at SATRA in the United Kingdom against the polyester wadding used in most synthetic quilts. The wool came back with far more of its original thickness.

Do Not Disturb has been making wool duvets from this material, unchanged, since 2023. In four years we have not had one fail.

How our wool actually gets made

It is worth knowing what happens between a sheep and a quilt, because in most of the industry a great deal happens, and it is why so much wool bedding needs chemistry to work.

The farm. The wool comes from more than 250 partner farming families on New Zealand's East Coast, around Gisborne, working to New Zealand Farm Assurance Programme standards. The region matters: its warm maritime climate grows strong wool with consistent staple length and very little plant matter in it.

Why that matters. Wool with a lot of plant matter has to be carbonised, which means treating it with acid to burn the vegetable matter out. Clean wool does not. Most wool used in bedding goes through carbonising, harsh detergent scouring, or bonding with synthetic resins to hold its shape. Ours goes through none of it.

The mill. The fibre is washed gently without chemicals, then needle-punched into blanketing at the Wisewool factory at Te Poi. The process is mechanical from end to end. No glues, no resins, no binders.

The wool itself. New Zealand strong wool at 36 to 39 micron. Coarser than merino, with more natural crimp, which is exactly what you want in a quilt: crimp is what holds air, and springiness is what lets it recover after being compressed all night.

The workroom. Every quilt is cut, filled and finished by hand in our Auckland workroom.

Nothing is added to the wool at any stage. No antibacterial finish, no biocide, no flame retardant. Wool passes fire testing untreated, which is why it does not need the chemistry that synthetic fill does.

So what GSM do you actually need?

Work from your bedroom, not from the calendar.

Room above about 18 degrees, or you sleep warm. 200 to 300 GSM. This covers most of Australia for most of the year, and all of the tropics all year.

Room below about 18 degrees, unheated or uninsulated, or you sleep cold. 350 to 500 GSM.

Genuinely cold winters, or you like weight on you. 500 GSM and up.

Not sure. Go lighter. The choice is not symmetrical: a quilt that turns out too light is fixed with a blanket over the top, and a quilt that turns out too warm cannot be made lighter. A hot sleeper under a 700 GSM quilt in February has an expensive problem and no solution.

Sharing with someone who runs colder than you. Buy for the warmer sleeper and let the other add a layer. Or buy two weights and swap them through the year.

Where our quilts sit

Do Not Disturb makes wool duvets in two weights, 200 GSM and 350 GSM, from needle-punched New Zealand strong wool. Known in Australia as a wool quilt or doona.

We do not make a 500 or a 700. In Australian terms our 200 is a summer weight and our 350 is an all-seasons weight, and if you are in Tasmania in July looking for maximum warmth from a single quilt, we are not the answer.

What we would say is that our two weights tie together at the corners, which makes 550 GSM of wool for the handful of nights a year that need it, and that on every other night you are sleeping under wool that is exactly where it was when you bought it.

For a wider comparison of fillings, see wool vs down vs synthetic.

What this means for you

Use GSM to get in the right range, then stop using it. It is a mass measurement doing a job it was never designed for.

Ask what the wool is, how it was processed, and whether the filling can move. Those three answers tell you more about how a quilt will perform, and far more about how it will perform in five years, than any number printed on the packaging.

And if you are uncertain between two weights, take the lighter one.

FAQ

What does GSM mean in a quilt? Grams per square metre. It is the weight of filling in one square metre of the quilt. A 350 GSM queen quilt holds a little over 1.5 kilograms of wool in total. It measures mass, not warmth.

What GSM is best for an Australian winter? 450 to 500 GSM in the southern states, more if your bedroom is unheated or you sleep cold. In Queensland, Western Australia and the Northern Territory many people use 200 to 350 GSM all year, including winter.

Is a higher GSM always warmer? No. Warmth comes from trapped air, not from mass. The fibre and the construction both change what a GSM figure delivers, which is why a 350 GSM wool quilt typically feels warmer than a 350 GSM microfibre one.

Why do wool quilts use GSM instead of fill weight? Because wool filling is supplied as a sheet rather than as loose clusters, so grams per square metre is the natural way to specify it. Down is measured by fill power instead, because for down the mass tells you even less.

What about tog ratings? Tog measures thermal resistance and is common in the United Kingdom. It is not widely used in Australia, where GSM is the standard.

Sources

• SATRA Technology Centre, compression testing to EN ISO 3385:2014, commissioned by Wisewool.

• NZWTA, flammability testing to BS 5852, commissioned by Wisewool.

• International Wool Textile Organisation, wool fibre properties.

• New Zealand Farm Assurance Programme, nzfap.com.

• GSM season ranges compiled from published guides by MiniJumbuk, Ecosa, Halcyon Dreams, Sienna Living and Best Quilt Australia, September 2026.