How Yarn Thickness Is Determined: A Complete Guide to Nm (Metric Count)

In the world of yarns, one of the most common questions is:

“How thick is this yarn?”

The answer, however, is not as simple as it seems. Unlike many materials, yarn thickness is not measured in millimeters, but through a technical system called yarn count, and one of the most widely used systems is Nm (Metric Count).

In this article, you’ll learn:

• what Nm means
• how yarn thickness is determined
• why two yarns with the same Nm can look completely different

What is Nm (Metric Count)

Nm (Metric Count) indicates how many meters of yarn there are in 1 gram of weight.

👉 Basic formula:
Nm = meters / grams

Examples:

• Nm 1 = 1 meter weighs 1 gram → very thick yarn
• Nm 10 = 10 meters weigh 1 gram → finer yarn
• Nm 28 = 28 meters weigh 1 gram → very fine yarn

Key rule:

👉 The higher the Nm = the finer the yarn
👉 The lower the Nm = the thicker the yarn

The actual thickness of a yarn depends on 3 main factors:

Yarn count (Nm) This is the technical base. It tells you how fine a single strand is.

Number of plies (folded yarns)

You often see yarns written like:

• 2/28
• 2/13
• 3/15

What does it mean?

👉 First number = number of plies
👉 Second number = count of each single yarn

Examples:

• 2/28 = 2 strands of Nm 28 twisted together
• 2/13 = 2 strands of Nm 13 → much thicker

📌 More plies = fuller and thicker yarn

Processing and knitting structure

Even with the same yarn:

• loose knitting = softer, bulkier result
• tight knitting = more compact, thinner feel
• rib, jersey, or English rib = completely different volume

👉 So: perceived thickness ≠ Nm alone

Why Two Yarns with the Same Nm Can Be Different

This is where most confusion comes from.

Two yarns both labeled Nm 2/28 can appear:

• fuller or flatter
• softer or firmer
• bulkier or more compact

It depends on:

• fiber type (cashmere vs merino vs cotton)
• fiber length
• twist level
• finishing processes (washing, fulling, brushing)

👉 Real example:
A recycled cashmere Nm 2/28 can feel bulkier than a virgin cashmere yarn with the same count.

Nm and Practical Use (Needles & Machines)

Here’s a practical guide based on real production experience:

• Nm 2/28
  • knitting machine: gauge 12 (single end)
  • hand knitting: 2 ends → needles 3–4
• Nm 2/13
  • knitting machine: gauge 7–8
  • hand knitting: needles 4–5
• Nm 1/3 – 1/5
  • very thick yarns
  • hand knitting: needles 6–10

👉 Keep in mind: these are guidelines, not strict rules.

Common Mistake: Thinking Nm = Actual Thickness

One of the most common mistakes is assuming Nm defines the exact thickness.

❌ Wrong
✔️ Nm defines the theoretical fineness of the yarn, not the final result

👉 The real thickness can only be evaluated by:

• knitting a swatch
• washing it
• observing how the fiber behaves

Professional Advice

If you knit or produce knitwear:

👉 Never rely on Nm alone

Always:

1. knit a sample
2. wash it
3. evaluate the final result

This is even more important with:

• recycled cashmere
• natural untreated yarns
• stock yarns

Nm is a fundamental tool to understand yarns, but it is not enough on its own.

To truly choose the right yarn, you must consider:

• yarn count (Nm)
• number of plies
• fiber type
• processing and finishing

👉 Only then can you accurately predict the final result.