Thread Count vs Qmax: What Actually Makes Sheets Cool
Updated September 2026 - 5 min read
Quick answer: Thread count measures one thing, how many threads are packed into a square inch of woven cotton. It says nothing about how breathable a sheet is, how it handles moisture, or how cool it sleeps. Our sheets are not woven cotton, so a thread count would not just be unhelpful, it would be meaningless. We publish a cool-touch rating instead.
Walk down any bedding aisle in Australia and the number shouting at you is thread count. 400. 800. 1200, with a little crown on the packaging. It has become shorthand for quality, which is impressive for a spec that was never designed to measure quality in the first place.
Here is what it actually measures, why we do not print one, and what to ask for instead.
What thread count actually measures
Thread count is the number of threads, horizontal and vertical, in one square inch of woven fabric. That is it. It is a density measurement for a specific type of construction: cotton, woven on a loom, in a percale or sateen weave.
It was never a comfort score. It was a manufacturing spec that drifted into marketing, and once shoppers started treating a bigger number as a better sheet, the number started growing.
The number can be inflated, and often is
Here is the part the packaging does not explain.
A single thread can be spun from several thinner strands, called plies. Count the finished threads and you get one number. Count every individual ply inside those threads and you get a much bigger one. Both get printed on boxes.
That is how a sheet arrives on the shelf wearing a four-figure thread count. The threads were not multiplied. The counting method was. And to reach those densities the individual fibres often have to get thinner and weaker, which is why a very high thread count sheet can feel dense and warm rather than crisp and cool, and can pill sooner than a lower-count one.
So thread count fails on its own terms. Two sheets with the same number on the box can be built completely differently, and the higher number is not reliably the better sheet.
Why it tells a hot sleeper nothing at all
Even a perfectly honest thread count would not answer the question most Australians actually have when they are buying sheets.
Around 51% of Australian adults sleep too hot at night at least once a week, and 22% say it happens every night or almost every night (OmniPoll, October 2025, n=1,004 Australians 18+, nationally representative, commissioned by REST and Morey Media). If you are one of them, the thing you need to know is how fast the fabric moves heat and moisture away from your skin.
Thread count does not measure heat. It does not measure moisture. It does not measure airflow. It measures density, and a denser weave usually traps more heat, not less. Which means the number people use as a proxy for luxury is, for a hot sleeper, frequently pointing in the wrong direction.
Woven versus knitted: the bit nobody explains
Here is the part that makes thread count irrelevant to us rather than just unhelpful.
Almost all bedding on earth is woven. Threads run in two directions and cross over and under each other in a grid, on a loom. Thread count is simply how many of those threads sit in a square inch of that grid. The measurement exists because the grid exists.
Evercool® is not woven. It is knitted: a single yarn looping through itself, loop after loop, on a circular knitting machine. There is no grid. There is nothing to count.
Asking a knitted fabric for its thread count is like asking a car for its horse count.
That is not a technicality, it is the whole reason the fabric behaves differently. A grid is a wall. Every time you raise the thread count, you pack more yarn into the same square inch and you close that wall a little further. You do buy softness. What you pay for it is air. A 1,000 thread count sheet is a beautifully made wall.
Loops are not a wall. A knitted structure has give and space built into it, so air can move through the fabric and heat can leave with it. Breathability is the thing that actually decides whether you are awake at 3am, and it is the first thing a high thread count gives away.
How ours is knitted. Our fabric is knitted at 36 to 40 gauge on a 300cm circular machine, fed by 156 cones of yarn at once, in a temperature-controlled room. The tolerances matter: the loop structure is what creates the airflow, so the knit is the product as much as the fibre is.
And the yarn inside it. One strand of our yarn is roughly the width of a human hair, and inside that single strand are 68 individual filaments. Each one is about 1.4 microns across, which means around 75 of our fibres laid side by side would make up the width of one hair. More filaments means more surface area, and more surface area means more contact points to carry heat and moisture away from your skin.
The fibre itself conducts heat at 0.24 to 0.31 W/mK. Cotton fibre sits at 0.04 to 0.06. That is roughly five times the thermal conductivity before you have even knitted it into anything.
What we publish instead: Qmax
Qmax measures cool-to-the-touch performance: how quickly heat transfers from your skin into the fabric on contact. Higher is cooler. It is tested by SGS, an independent laboratory, and it is the closest thing bedding has to an honest cooling number. If you want the full method, we have written a separate explainer on what Qmax is and how it is measured.
There is a line, and most fabrics do not clear it. For a fabric to be described as cool touch at all, it needs to score at least 0.18. Cotton scores 0.11. Cotton does not narrowly trail the cool-touch category. It does not qualify for it.
| Fabric | Qmax (W/cm²) |
|---|---|
| Evercool®+ (Rest sheets and pillowcases) | 0.445 |
| Evercool® (Rest comforter) | 0.433 |
| Cool-touch threshold | 0.18 |
| Cotton | 0.11 |
Our sheets and pillowcases test at 0.445, the highest of anything we make. That is over four times cooler to the touch than cotton, and it is not a copywriting decision. It is a lab report, and the full results are on our third-party test results page.
The reason the touch layer tests highest is silver. Ionic+® silver sits inside the fibre itself, not sprayed on top of it and not a coating that washes away, and silver conducts heat at 429 W/mK. Putting a conductor that efficient into the layer that touches you all night is the difference between 0.433 and 0.445.
Cool is one third of the job
A cooling number on its own does not get you through a hot night, because heat is not the only thing your body is trying to move.
Dry. Sweat has to go somewhere. Our fabric moves it through four stages: absorb it off the skin, transport it into the structure, wick it across a wide surface area, then evaporate it. The point is not that you never sweat. The point is that you are not lying in it.
Clean. The Ionic+® silver in the fibre keeps the fabric itself fresher between washes, so the sheet you get into on night six feels like the sheet you got into on night one.
Cool, dry, clean. Thread count measures none of them.
The one number worth asking for
You do not have to take our word for any of this, and you should not have to. Ask for the number.
If a brand sells cooling bedding, ask what its Qmax is and who tested it. If the answer is a thread count, a fibre name, or the word “breathable” on a swing tag, you have your answer. Ours is 0.445 for the sheets and pillowcases and 0.433 for the comforter, tested by SGS, and it is published on our Science hub.
If you sleep hot, start with the Evercool®+ Cooling Starter Sheet Set, or read more about what we build for hot sleepers. If the comforter is the problem, the Evercool® Comforter is built on the same principle.
Why Rest
- Good Housekeeping Bedding Award - 4x winner
- Red Dot Award (2026) - Product Design winner
- Health Sleep Award (2025)
- SleepScore Validated (2025) - third-party sleep research validation
- OEKO-TEX® certified - tested for harmful substances
As seen in GQ, Marie Claire, Women’s Fitness and Home Beautiful.
Quick FAQ
Is a higher thread count better? Not for temperature. Thread count measures how densely threads are packed into woven cotton, and packing them tighter closes the fabric up. You gain softness and you lose airflow. For a hot sleeper, a very high thread count often works against you.
Does thread count matter at all? For woven cotton sheets it tells you something about density, and the commonly cited useful range sits between roughly 200 and 600. Beyond that, higher numbers usually reflect how the threads were counted rather than a better sheet.
What is a good thread count for hot sleepers? The more useful question is what the fabric is made of and how it is built. A lower thread count percale will usually sleep cooler than a high thread count sateen, but neither will match a fabric engineered and tested for heat transfer. Ask for a Qmax figure instead.
Why do Rest sheets not have a thread count? Because thread count only exists in woven fabric. Our Evercool®+ sheets are knitted rather than woven, so there is no thread grid to count. We publish an SGS-tested Qmax score instead, which measures how fast the fabric moves heat away from your skin.
What is a good Qmax? A fabric needs to score at least 0.18 to be called cool touch at all. Cotton sits at 0.11, so it does not reach the threshold. Evercool®+ sheeting tests at 0.445 W/cm², independently tested by SGS.
Is cooling bedding only for summer? No. Rest bedding is built to manage heat and moisture year-round. People who run hot run hot in July too.