Why Your Bedding's Qmax Score Matters More Than the Thread Count
If you've ever woken up at 3am in a puddle of your own heat, this one's for you.
Most people shopping for cooling bedding are looking at the same things: thread count, fill weight, whether the packaging says "breathable." The problem is none of those numbers actually tell you how a fabric feels against your skin the moment you climb into bed.
Qmax does.
What is Qmax?
Qmax - short for maximum heat flux - is the measurement textile scientists use to quantify how quickly a fabric draws heat away from your body on first contact. It's the number behind that instant cool-touch feeling when you press your hand against certain fabrics.
The higher the Qmax score, the faster heat moves away from your skin. The lower the score, the more heat stays trapped against your body - and the warmer you sleep.
It's measured in watts per square centimetre (W/cm²), and it's the most objective way to compare cooling fabrics on the market.
Cotton vs Evercool®: The Numbers
Standard cotton sits at a Qmax of 0.11 W/cm². It absorbs your body heat slowly, holds it in the fabric, and traps moisture against your skin. By 3am you're effectively sleeping inside an oven - and if you're a hot sleeper, you already know exactly what that feels like.
Rest Evercool® fabric scores a Qmax of 0.445 W/cm² - four times more thermally conductive than cotton. Heat moves away from your body fast, the fabric stays cool to the touch throughout the night, and you stop waking up overheated.
That's not a marketing claim. It's a physics problem with a measurable solution.
Why Cool-Touch Fabric Isn't Just About Feeling Cold
There's a common misconception that cool-touch fabric is about making you feel cold when you get into bed. It isn't.
Your core body temperature needs to drop by approximately 1-2°C to initiate deep sleep. If the layer touching your skin is trapping heat rather than conducting it away, your body has to work harder to reach that threshold. The result is lighter sleep, more frequent wake-ups, and that worn-out feeling in the morning even after a full eight hours.
Cool-touch fabric with a high Qmax score doesn't refrigerate you - it gets out of the way of your body's natural cooling process instead of fighting against it.
What Else Is in the Fabric
Qmax is the lead number but it's not the only thing worth knowing about Evercool® fabric.
The weave is designed to wick moisture at a rate of ≥100mm per 10 minutes - meaning sweat moves through the fabric instead of pooling against your skin. The damp patch disappears. You stay dry.
The fabric also incorporates Ionic+® silver yarn woven directly into the structure - not sprayed on, not a coating that washes out over time. This keeps the fabric fresher for longer without any additional treatment needed.
And for anyone with sensitive skin, Rest Evercool® is OEKO-TEX certified - independently tested and verified free from harmful substances. What's touching your skin for eight hours a night has been assessed to the Standard 100 by OEKO-TEX.
The One Number Worth Asking About
Thread count became the dominant bedding metric because it was easy to understand and easy to print on packaging. The problem is it measures quantity, not performance. A 1000 thread count cotton sheet still has a Qmax of 0.11.
If you're shopping for and you run warm at night, Qmax is the number that actually predicts how you'll sleep. Everything else is marketing.
You can read the full breakdown of how Evercool® fabric is tested and what the data means on our .
 Evercool® Cooling Comforter
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The Bottom Line
Cotton feels familiar. It's what most of us grew up sleeping on. But familiar isn't the same as functional - especially if you run warm at night or deal with night sweats regardless of the season.
The fabric touching your skin for eight hours a night is either helping your body do its thing, or getting in the way.
Qmax tells you which one.
Rest Evercool® is available in comforters and sheet sets. 30-night trial, free returns.