Yarn weight refers to the thickness of a strand of yarn. It is an important factor to consider when choosing yarn for a project because it determines the amount of yarn needed and the finished product’s drape, texture, and gauge.
Yarn weight can range from lace to super bulky and is indicated by a number or category name, such as “fingering” or “worsted.” These categories were set as a standard in the US by the Craft Yarn Council.
Using the appropriate yarn weight for a project can help ensure that it turns out as intended.
What are Yarn Weight Numbers?
Yarn weight actually has nothing to do with how much it weighs, but with the overall thickness of the strand of yarn.
These yarn weight numbers range from 0-7. Each weight also has a couple of names to it that may be a little easier to remember. The lower the number, the thinner the yarn is. Conversely, the higher the number, the thicker it is.
|Weight #||Weight Name (aka)|
|#0||Lace (2-ply, Cobweb)|
|#1||Super Fine (Sock, Fingering, Baby)|
|#2||Fine (Sport, Baby)|
|#3||Light (DK, Light Worsted)|
|#4||Medium (Worsted, Afghan, Aran)|
|#5||Bulky (Chunky, Craft, Rug)|
|#6||Super Bulky (Roving, Super Chunky)|
Certain projects require specific yarn weights too. For example, a blanket might require a thicker yarn – usually anywhere between at “4,” “5,” or “6” weight yarn – whereas a project in appliquéing might call for a lighter weight yarn, such as a “2” or “3” weight.
These different yarn weights are used to account for the differences in the projects they are used for. For instance, if you want to crochet a cozy blanket to keep you warm in the winter, you would likely use a thicker yarn than you would if you were using a thinner, worsted weight yarn for a lighter blanket or different project.
How Yarn Weights & Crochet Hooks Work
Every ball (or skein, hank, cone, cake, etc.) of yarn typically has a sheet of paper wrapped around it that provides various bits of information around how to use that particular yarn. The two information pieces relevant here are the gauge swatch, and yarn weight icon.
The yarn weight icons all have a similar look and feel to them. They will all be a graphic that looks like a skein of yarn, with a number inside of it. That number corresponds to the yarn’s weight.
Next, inside that gauge swatch area, you’ll actually see two swatches listed. One for crochet, and the other for knitting. Both of these will tell you the preferred gauge of that particular yarn. The crochet gauge will suggest a crochet hook to use (J10 in the example above) with their yarn, and how many stitches and rows should comprise a (usually) 4×4″ swatch.
While it is up to each manufacturer to recommend a hook size, they typically do follow a pattern. Here is a table with they suggest crochet hooks per yarn weight.
|Yarn Weight||Hook Sizes|
|#0 – Lace||1.5 – 2.25 mm (B1)|
|#1 – Super Fine||2.25 – 3.25 mm (B1, C2, D3)|
|#2 – Fine||3.25 – 3.75 mm (D3, E4, F5)|
|#3 – Light||3.75 – 4.5 mm (F5, G6, 7)|
|#4 – Medium||4.5 – 5.5 mm (7, H8, I9)|
|#5 – Bulky||5.5 – 8 mm (I9, J10, K10.5, L11)|
|#6 – Super Bulky||8 – 12.75 mm (L11, M13, N15, P)|
|#7 – Jumbo||12.75 mm + (Q, S)|
What Are Plies in Yarn?
Most yarn is made up of plies, but the US doesn’t follow along with these norms. The UK and Australia name their yarn weights based on plies, whereas the US groups them based on thickness.
A 2-ply yarn, for example, is composed of two strands, and a 3-ply yarn is composed of three, and so on.
|#0 – Lace||1 ply||2 ply|
|#1 – Super Fine||2 ply||3 ply|
|#2 – Fine||3 ply||3 ply|
|#2 – Fine||4 ply||5 ply|
|#3 – Light||DK||8 ply|
|#4 – Medium||Aran||10 ply|
|#5 – Bulky||Chunky||12 ply|
|#6 – Super Bulky||Super Chunky||14 ply|
|#7 – Jumbo||n/a||n/a|
What is Wraps Per Inch (WPI)?
WPI is a way to measure yarn weight by the number of wraps it takes to go one inch around a ruler or pencil. To measure yarn weight using the WPI method, wrap the yarn around a small object like a pencil or crochet hook for one inch. The wrapped yarn should be side by side and not overlapping. The thicker the yarn, the fewer wraps it will take to reach that one inch marker.
|#0 – Lace||32+|
|#1 – Super Fine||14-30|
|#2 – Fine||12-18|
|#3 – Light||11-15|
|#4 – Medium||9-12|
|#5 – Bulky||6-9|
|#6 – Super Bulky||5-6|
|#7 – Jumbo||0-4|