Why Two Yarns with the Same Nm Can Look Different

It often happens to hear this question:
“How is it possible? They have the same Nm, yet they look like completely different yarns!”

It’s a perfectly reasonable doubt.
The Nm indicates the theoretical thickness, but it doesn’t tell the whole story of a yarn.

Let’s see why.

Nm Measures Weight, Not Appearance

The Nm yarn count only tells us one thing:
👉 how many meters of yarn weigh one gram

It does not describe:

• softness

• volume

• compactness

• hand feel

• visual appearance

As a result, two yarns can have the same length and the same weight, yet behave and look very different.

1️⃣ Type of Fiber

The fiber used makes a huge difference.

With the same Nm:

• cashmere looks fuller and softer

• worsted wool appears more compact

• cotton feels stiffer

• recycled yarns may look bulkier

👉 Different fibers = different perception.

2️⃣ Carded vs. Combed Yarn

• Carded yarn:

  • more air inside

  • puffier appearance

  • softer hand

• Combed (worsted) yarn:

  • aligned fibers

  • smoother surface

  • more compact structure

👉 Same Nm, completely different volume.

3️⃣ Yarn Twist

Twist plays a major role.

• low twist → softer, rounder, bulkier yarn

• high twist → firmer, drier, more compact yarn

A highly twisted yarn can look thinner, even though its Nm is exactly the same.

4️⃣ Number of Plies (Ply Structure)

A Nm 2/28 and a Nm 1/14 may have a similar overall count, but:

• plied yarns are more even

• they hold structure better

• they behave differently when knitted

How strands are combined directly affects the final yarn structure.

5️⃣ Finishing and Treatments

Washing, fulling, and finishing processes change:

• volume

• hand feel

• elasticity

A finished yarn will look fuller and softer than an untreated one, even if the Nm is identical.

Imagine two jackets:

• same weight

• same declared insulation level

One is filled with goose down, the other with synthetic fiber.

👉 On paper, they look the same.
👉 In reality, they are not.

Yarns behave in exactly the same way.

Nm is essential, but it’s not enough on its own to truly understand a yarn.

To properly evaluate yarn thickness and performance, you must also consider:

• fiber type

• spinning process

• twist

• structure

• finishing

That’s why touching the yarn, testing it, and knowing its origin remain irreplaceable—even today.