What is Nm?
Nm (Numero metrico) is the metric yarn count system used throughout the European textile industry, particularly in Italy. It tells you how many meters of yarn weigh one gram.
- Nm 28 means 28 meters of single yarn weighs 1 gram (or 28,000 m/kg)
- The higher the Nm, the finer the yarn
- The lower the Nm, the thicker the yarn
Why Lower Nm = Thicker Yarn
Think of it this way: Nm tells you how many meters of yarn fit in just 1 gram. A thin, delicate yarn has lots of meters per gram (high Nm). A thick, heavy yarn has very few meters per gram (low Nm).
- 2/60 (Nm 30) — ─────── fine, 3,000 m/100g
- 2/48 (Nm 24) — ━━━━━━ medium, 2,400 m/100g
- 2/28 (Nm 14) — ▬▬▬▬▬ thick, 1,400 m/100g
- 2/11 (Nm 5.5) — ████ very thick, 550 m/100g
The key insight: 1 gram of 2/60 gives you 30 meters of thread. The same 1 gram of 2/11 gives only 5.5 meters — because the yarn is much thicker and heavier per meter.
Reading Yarn Count Notation: Plies/Nm
Yarn counts are typically written as plies/Nm. For example:
- 2/28 = 2 plies of Nm 28 singles
- 1/15 = single ply of Nm 15
- 3/48 = 3 plies of Nm 48 singles
To find the effective Nm of a plied yarn, divide the singles Nm by the number of plies:
Effective Nm = Singles Nm / Number of Plies
So 2/28 has an effective Nm of 28 / 2 = Nm 14 (14,000 m/kg or 1,400 m/100g).
Converting Nm to Meters per Kilogram
The relationship is simple:
- m/kg = Nm x 1,000
- m/100g = Nm x 100
Examples:
| Yarn | Effective Nm | m/kg | m/100g |
|---|---|---|---|
| 2/28 | 14 | 14,000 | 1,400 |
| 2/48 | 24 | 24,000 | 2,400 |
| 1/15 | 15 | 15,000 | 1,500 |
| 3/48 | 16 | 16,000 | 1,600 |
Combining Yarns: The Harmonic Formula
When you knit or weave with multiple yarns held together, the resulting yarn count is calculated using the harmonic reciprocal formula:
1/Nm(result) = 1/Nm(1) + 1/Nm(2) + 1/Nm(3) + ...
Example: Combining 2/28 with 2/48
- Effective Nm of 2/28 = 28 / 2 = 14
- Effective Nm of 2/48 = 48 / 2 = 24
- 1/Nm(result) = 1/14 + 1/24 = 38/336
- Nm(result) = 336/38 ≈ 8.84
- That gives us approximately 8,842 m/kg or 884 m/100g
Why Harmonic and Not Simple Average?
When you hold two yarns together, each contributes its own weight per meter. A thicker yarn (lower Nm) adds more weight than a thinner one. The harmonic formula correctly accounts for this — the result is always closer to the thicker yarn's Nm, which matches physical reality.
Nm vs Other Count Systems
| System | Unit | Used In | Higher Number Means |
|---|---|---|---|
| Nm (Metric) | m/g | Europe, Italy | Finer yarn |
| Ne (English Cotton) | 840 yd/lb | Cotton industry | Finer yarn |
| Tex | g/1000m | International | Thicker yarn |
| Denier | g/9000m | Synthetic fibers | Thicker yarn |
Quick Conversions
- Nm to Tex: Tex = 1000 / Nm
- Nm to Ne: Ne = Nm x 0.59
- Nm to Denier: Denier = 9000 / Nm
Try It Yourself
Use our Yarn Nm Calculator to instantly calculate the resulting Nm when combining multiple yarns. Enter the ply count and Nm for each yarn, and see the result in both m/kg and m/100g.