What are Yarn Weights?

Posted by Alison Manning on

What are the various yarn weights and what do they really mean?

If I had a nickel for every time I was asked “What does Fingering, DK or Worsted mean?”, I’d own a flat in central London and possibly a small island in the Caribbean. This is one of the most frequent questions we get at Unraveled so let’s talk about it.

You will have noticed that some yarns are very thin, and some are the thickness of your finger – or larger. Fingering, DK and Worsted – among others, are terms for the relative thickness of a strand of yarn and is called its “weight”. It is this characteristic, defined as the wraps per inch or wpi, that is being referenced. It is not a discussion of the physical mass of the yarn so don’t let that mislead you.

Wraps per Inch

Historically, yarn was made at home on a spindle and later, on a spinning wheel and so the relative thickness or thinness of the yarn was driven by what the person was spinning the yarn for and didn’t need to meet an industrial standard. As yarn production became mechanized, standards started to evolve. One of those standards is called Wraps per Inch – or wpi. If you look up any yarn in Ravelry, you’ll see this number. This refers to how many times the yarn can be wrapped around a measuring tool in an inch.

This is the magic number. This number is how the different yarn weights are determined. There are still tools made for this and broadly speaking, hand spinners care about it more than most knitters but this is where the categorization comes from. So, if I can wrap my yarn around a measuring tool 16 times (as shown in the photo above), that is termed a fingering weight yarn. If I can only wrap my yarn around the tool 10 or 11 times, that is termed a worsted.

This chart shows the various wpi’s of different yarns.  Note the variety of names which are used in different places.





Wraps Per Inch,

Recommended knitting needle size, mm,

Other names used

0 or Lace

1 ply

More than 800

40+ wpi

1.5 - 2.5

Single, Cobweb, Thread, Zephyr

0 or Lace

2 ply


30-40 wpi

1.5 - 2.5

1 or Super Fine

3 ply

3 ply


20-30 wpi

2 - 3

Light Fingering, Sock, Baby

1 or Super Fine

4 ply

4 ply


14-24 wpi

2 - 3

Fingering, Sock, Baby

2 or Fine

5 ply


12-18 wpi

3 - 4

Sport, Baby, 3-ply (obsolete American)

3 or Light

DK (Double Knit) or 8 ply

8 ply


11-15 wpi

4 - 4.5

Light Worsted, DK

4 or Medium

Worsted, Aran, Triple Knit (rare)

10 or 12 ply


9-12 wpi

4.5 - 5.5

Worsted, Afghan, Fisherman, 4-ply (obsolete American)

5 or Bulky

Chunky, Double Double Knit (rare)

12 or 16 ply


6-8 wpi

5.5 - 8

Craft, Rug

6 or Super Bulky

Super Chunky

Less than 100

5-6 wpi



7 or Jumbo

Less than 100


12.75 mm and larger



As you can see, there is often some overlap in the wpi ranges which as you might guess, blurs the distinction between weights i.e. if there are 16 wraps per inch, is it a sport weight or a fingering weight? This is where gauge comes into play and personally, I find when substituting yarn that searching for a specific gauge is a better guide for yarn substitution than a broad ranging bucket like "Fingering". That said, knowing that I should start my search in Fingering is helpful too.

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