Why two yarns with the same Nm can look different
We often hear this phrase:
"How is it possible? They have the same Nm, yet they seem like different yarns!"
It's a perfectly legitimate question.
The Nm indicates the theoretical thickness, but it doesn't tell the whole story of the yarn.
Let's see why.
Nm measures weight, not appearance
The Nm count only tells you:
👉 how many meters of yarn there are in one gram
It says nothing about:
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softness
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volume
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compactness
-
hand
-
visual appearance
Two yarns can therefore have the same weight and the same length, but behave completely differently.
1️⃣ Fiber type
The fiber used changes everything.
For the same Nm:
-
cashmere appears fuller and softer
-
worsted wool is more compact
-
cotton appears stiffer
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recycled yarn can seem more voluminous
👉 Different fibers = different perception.
2️⃣ Carded or combed yarn
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Carded:
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more air inside
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fluffier appearance
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softer hand
-
-
Combed:
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aligned fibers
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smoother surface
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more compact yarn
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👉 Two identical Nm, but completely different volume.
3️⃣ Yarn twist
The twist has a huge impact.
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low twist → softer, "chubbier" yarn
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high twist → drier, more compact yarn
A highly twisted yarn can appear thinner, even with the same Nm.
4️⃣ Number of plies (plied yarn)
An Nm 2/28 and an Nm 1/14 have a similar count, but:
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the ply is more regular
-
it holds the knit better
-
it has a different visual appearance
The way the strands are joined changes the final structure.
5️⃣ Finishing and treatment
Washing, fulling, and finishing modify:
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volume
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hand
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elasticity
An already treated yarn will appear fuller than a raw one, even if the Nm is identical.
Imagine two down jackets:
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same weight
-
same declared volume
One is goose down, the other is synthetic.
👉 On paper, they're the same.
👉 In reality, they're not.
The exact same thing happens with yarns.
The Nm is fundamental, but it alone is not enough to understand a yarn.
To truly assess a thickness, you must consider:
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fiber
-
processing
-
twist
-
structure
-
finish
This is why touching the yarn, trying it, and knowing its origin remains irreplaceable.
