Denier / Tex / Dtex Converter
Convert yarn linear density between denier, tex, and decitex (dtex).
Reviewed by the ToolNestr Editorial Team — July 2026
How the denier/tex/dtex conversion works
All three units follow the same underlying idea — weigh a fixed length of yarn and use that weight in grams as the thickness number — but each uses a different reference length. Denier weighs 9,000 meters, tex weighs 1,000 meters, and decitex (dtex) weighs 10,000 meters. Because these lengths are exact multiples of each other, converting between them is straightforward division and multiplication: tex equals denier divided by 9, and dtex equals denier multiplied by 10/9.
These are all "direct" numbering systems, meaning a bigger number always means a thicker, heavier yarn — this is the opposite of "indirect" systems like Ne cotton count, where a bigger number means a finer yarn, which is why converting between a direct and indirect system (see the Yarn Count Converter) requires a different kind of formula entirely.
Denier, tex, and decitex are internationally standardized yarn linear-density units (ISO 1144); the conversion factors used here are exact by definition, not approximations.
Worked example
A pair of tights is labeled 70 denier, and the equivalent tex and dtex values are needed for a spec sheet.
Real-world context
Sourcing synthetic yarn or thread from an overseas mill is the most common place this conversion matters in practice, since a US-based buyer used to denier specifications may receive a supplier's technical sheet listing everything in tex or dtex, and comparing yarn options across suppliers requires converting them all to one common unit first.
Hosiery and legwear specifically use denier as a consumer-facing marketing number (sheer 8-denier tights versus opaque 100-denier tights), while the underlying technical yarn specifications a manufacturer works from are frequently recorded in tex or dtex, making this conversion a routine bridge between consumer labeling and production specs.
Common misconceptions
"Denier measures the fabric's overall weight, like GSM." No. Denier measures the yarn's own thickness before it's woven or knit into fabric; a fabric's finished GSM depends on both yarn denier and how tightly it's constructed, so the two numbers aren't interchangeable.
"Denier and Ne cotton count can be converted the same simple way." They can't. Denier is a direct system (bigger number = thicker yarn) while Ne is indirect (bigger number = finer yarn), so converting between them uses an inverse relationship, not simple multiplication.
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Frequently asked questions
What do denier, tex, and dtex actually measure?
All three measure linear density — how much a fixed length of yarn or thread weighs. Denier is grams per 9,000 meters, tex is grams per 1,000 meters, and decitex (dtex) is grams per 10,000 meters. A higher number in any system means a thicker, heavier yarn.
Which system is used where?
Denier is common in the US for hosiery, synthetic filament yarns, and fabric weight claims (like "40 denier tights"). Tex and decitex are the international (SI-based) standard used more broadly across global textile manufacturing and technical specifications.
Why is the conversion factor 9 between denier and tex?
It comes directly from the definitions: denier is weight per 9,000 meters and tex is weight per 1,000 meters, a 9-to-1 length ratio, so the same yarn's denier number is always 9 times its tex number.
Is a 70 denier fabric thicker than a 40 denier fabric?
Yes — in denier, tex, and dtex, all higher numbers mean a thicker, heavier yarn (this is the opposite of indirect systems like Ne cotton count, where a higher number means a finer yarn).