The Truth About Thread Count: What 600TC Actually Means

Thread count is one of the most misunderstood numbers in the bedding industry. It has been inflated, manipulated, and used as a marketing shorthand for quality in ways that are, at best, misleading — and at worst, the subject of lawsuits. We think you deserve a plain-English explanation of exactly how we calculate ours, and why the number on the label tells only part of the story.

What Thread Count Actually Means

At its most literal, thread count is the number of threads woven into one square inch of fabric — horizontal threads (the weft) plus vertical threads (the warp). A fabric with 150 threads running each way would have a thread count of 300. Simple enough.

The complication arises from how those threads are made.

The Ply Problem: Where the Numbers Diverge

A thread doesn't have to be a single strand. It can be twisted from two, three, or more finer strands — these are called plies. A 2-ply thread is two fine strands twisted together into one. A 3-ply thread is three.

This is where the bedding industry split into two very different counting methods:

The Commercial Method (what most brands use): Count every individual ply as a separate thread. A fabric with 300 threads per square inch, each made from 2 plies, becomes a "600 Thread Count" sheet. The plies are multiplied into the headline number.

The Technical Standard — ASTM D 3775: This is the strict definition set by the American Society for Testing and Materials, the body that governs textile testing in the United States. Under ASTM D 3775, a thread is a thread — regardless of how many plies it contains. That same 300-thread fabric is a 300 Thread Count sheet, full stop.

A Plain-English Analogy

Imagine a fence built from ropes, where each rope is twisted from two smaller strings.

• ASTM standard: You count 10 ropes. Thread count = 10.
• Commercial standard: You count 10 ropes × 2 strings each. Thread count = 20.

Same fence. Same ropes. Two very different numbers — depending on who's counting and why.

Why This Matters: A Brief History of Thread Count Inflation

For years, the bedding industry used multi-ply yarns not to improve quality, but to inflate thread count numbers. Brands advertised 800TC, 1000TC, even 1200TC sheets — sheets that, under the ASTM standard, would have been a fraction of that. Many of those sheets felt like sandpaper. The inflated numbers were a function of cheap, multi-ply construction, not fine weaving.

The industry faced significant scrutiny and legal action as a result. Retailers and manufacturers were challenged over misleading thread count claims, and the gap between commercial marketing and technical reality became impossible to ignore.

Our Position: Honest by Design

Our SUPIMA® cotton percale sheets are marketed at 600 Thread Count using the commercial method — counting individual plies within each yarn. Under the strict ASTM D 3775 standard, the same fabric would be classified at a lower number.

We are telling you this directly because we believe you should know exactly what you are buying.

But here is what the thread count number cannot tell you: the quality of the fibre itself. Our sheets are woven from 100% certified SUPIMA® Extra-Long Staple cotton — the finest cotton grown in the world, handpicked in the American west and southwest, and finished by artisans in Tuscany. The length, strength, and fineness of the ELS fibre is what produces a fabric that is genuinely soft, genuinely durable, and genuinely worth sleeping in.

A high thread count made from short-staple, multi-ply cotton produces a heavy, rough fabric that degrades quickly. A lower technical thread count made from SUPIMA® ELS cotton produces something that gets softer with every wash and lasts for years.

Thread count is a starting point. Fibre quality is the whole story.

The Number to Trust

If you are comparing sheets, here is our honest advice: look past the headline thread count and ask what the cotton actually is. Is it certified? Is it traceable? Is it Extra-Long Staple?

Those questions will tell you more about how a sheet will feel and last than any number on a label — commercial or otherwise.