Yarn Weight & Wpi

One way of determining the weight of an unknown yarn is to use the wrapping method. This convenient method is also used to calculate the amount of yarn needed for a project. By this method it is possible to check yarn with a simple pencil and ruler Wrap the yarn around a large needle or a ruler. Make sure the yarn lies flat. Push the yarn together so there are no gaps between wraps. Smooth it out so it is neither too loose nor too tight. Measure the number of wraps per inch (2.5 cm).

The number of wraps will act as a gauge to assess the thickness of unmarked yarn; for example 12 wraps per inch is 12 WPI, and is used to calculate how much yarn is required for various articles so that 12 WPI is equivalent to 8 ply (worsted weight, medium weight) yarn.

US

UK

Australia

m/100g

Wraps Per Inch,

Recommended knitting needle size, mm

Recommended crochet hook size, mm

Other terms used

0 or Lace

1 ply

More than 800

40+ wpi

1.5 - 2.5

1.5 - 2.5

Single, Cobweb, Thread, Zephyr

0 or Lace

2 ply

600-800

30-40 wpi

1.5 - 2.5

1.5 - 2.5

1 or Super Fine

3 ply

3 ply

500-600

20-30 wpi

2 - 3

2.25 - 3.5

Light Fingering, Sock, Baby

1 or Super Fine

4 ply

4 ply

350-450

14-24 wpi

2 - 3

2.25 - 3.5

Fingering, Sock, Baby

2 or Fine

5 ply

250-350

12-18 wpi

3 - 4

3.5 - 4.5

Sport, Baby, 3-ply (obsolete American)

3 or Light

DK (Double Knit) or 8 ply

8 ply

200-250

11-15 wpi

4 - 4.5

4.5 - 5.5

Light Worsted, DK

4 or Medium

Worsted, Aran, Triple Knit (rare)

10 or 12 ply

120-200

9-12 wpi

4.5 - 5.5

5.5 - 6.5

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

5 or Bulky

Chunky, Double Double Knit (rare)

12 or 16 ply

100-130

6-8 wpi

5.5 - 8

6.5 - 9

Craft, Rug

6 or Super Bulky

Super Chunky

Less than 100

5-6 wpi

>8

>9

Roving

7 or Jumbo

Less than 100

n/a

12.75 mm and larger

15 mm and larger

Roving


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