Converting yarn count is easiest if you always go through one system. Tex is the natural choice because it is a direct system (grams per kilometer) and because fabric weight formulas use it.
The conversion constants#
| From | To tex | From tex |
|---|---|---|
| Ne (cotton) | tex = 590.54 / Ne | Ne = 590.54 / tex |
| Nm (metric) | tex = 1000 / Nm | Nm = 1000 / tex |
| Denier | tex = den / 9 | den = tex × 9 |
| dtex | tex = dtex / 10 | dtex = tex × 10 |
| Worsted (Nw) | tex = 885.8 / Nw | Nw = 885.8 / tex |
| Linen lea (Nl) | tex = 1653.5 / Nl | Nl = 1653.5 / tex |
Where the constants come from#
Take Ne: one Ne means 840 yards in one pound.
- 840 yards = 840 × 0.9144 = 768.1 m
- 1 pound = 453.59 g
- So Ne 1 = 768.1 / 453.59 = 1.6934 meters per gram
- Tex is grams per 1,000 m, so tex = 1000 / (1.6934 × Ne) = 590.54 / Ne
The worsted constant uses 560 yards and the linen constant 300 yards in the same way.
Worked examples#
Direct shortcuts between indirect systems#
You can skip tex when converting between Ne and Nm:
And between denier and Ne:
The 5315 comes from 590.54 × 9.
Folded (plied) yarns#
For a folded yarn made of identical singles, ignoring twist contraction:
- In a direct system, add the counts: 2 plies of 20 tex = 40 tex.
- In an indirect system, divide: 2 plies of 40s Ne = 20s Ne.
For singles of different counts, convert each to tex and add them. For example, a two-ply of 40s and 30s Ne: 14.76 + 19.68 = 34.44 tex, which is 590.54 / 34.44 = 17.1 Ne.
Twist makes each singles strand a little shorter, so the real folded yarn is slightly coarser than this calculation. When exact weight matters, take the tested resultant count from the spinner.
Blended and core-spun yarns#
For a blended yarn (for example 60/40 cotton polyester), the count is measured on the finished blend like any other yarn. Composition percentages do not change the conversion.
For core-spun yarns with an elastane or filament core, the count stated by the spinner is usually the resultant count of the whole yarn. The elastane is often specified separately in denier (for example 20 den or 40 den) together with its draft. Ask which figure the supplier means.
Conversion table#
| Ne | Tex | dtex | Denier | Nm |
|---|---|---|---|---|
| 10 | 59.1 | 591 | 531 | 16.9 |
| 20 | 29.5 | 295 | 266 | 33.9 |
| 26 | 22.7 | 227 | 204 | 44.0 |
| 30 | 19.7 | 197 | 177 | 50.8 |
| 34 | 17.4 | 174 | 156 | 57.6 |
| 40 | 14.8 | 148 | 133 | 67.7 |
| 50 | 11.8 | 118 | 106 | 84.7 |
| 60 | 9.8 | 98 | 89 | 101.6 |
| 80 | 7.4 | 74 | 66 | 135.5 |
Common mistakes#
- Dividing when you should multiply. Check the direction: finer yarns have higher Ne and lower tex.
- Using 590 instead of 590.54 for precise work. The difference is small but adds up in specifications.
- Adding indirect counts for folded yarns. Two 40s singles do not make an 80s yarn; they make about a 20s.
- Forgetting ply in fabric calculations. A 2/40s warp in a woven construction is about 29.5 tex, not 14.8.
The yarn count converter shows all systems at once and handles folded yarns. For what the numbers mean in practice, see yarn count explained.
Related guides#
- Fabric GSM: how yarn count feeds into fabric weight.
- Fabric construction analysis: finding the count of yarns taken out of a fabric sample.
- Single jersey fabric: the counts commonly used for T-shirt jersey.
- Sewing thread selection: sewing thread ticket numbers, which use their own count systems.
- Fabric GSM chart: typical fabric weights that different counts produce.