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Yarn Weight Categories, Conversion, and Global Standards Explained


Klara Nilsson | Updated on November 27, 2021

Find out exactly what international yarn weight categories mean, how to measure them, and how to use a yarn weight conversion chart to convert from one weight standard to another.
different yarn weights
Quick Summary: Yarn weight refers to the thickness of the yarn you’re knitting with. It affects how your finished fabric looks and feels, how long it takes to knit, and how much yarn you need overall. Yarn weight standards vary internationally. In the US, the standard weight categories range from Lace (0) to Jumbo (7) in order of the thinnest to thickest yarns.

This guide will teach you everything you need to know about yarn weight, including all of the different international standards, categories, and labels. You’ll find out how to test the weight of your yarn and convert between different weight types.

If you’re just beginning to learn about knitting, you’re probably still figuring out how yarn actually works. You might’ve bought some yarn just because it looks nice, without figuring out what can actually knit with it!

For most knitting projects, choosing the right yarn weight is a vital step in creating a material or fabric that matches your expectations. If you make the wrong decision, you might end up with a sock, blanket, or sweater that looks and fits completely different to the item you had imagined.

Familiarising yourself with yarn weights early will make your knitting life much easier, but it isn’t always easy – especially if you’re working with yarns and patterns from all over the world.

Just like with knitting needle sizes, different countries have different naming systems, terms, and definitions for yarn weights.

That’s why we’ve created this handy, step-by-step guide to yarn weights. By the end of this article, you’ll know exactly what each weight category means and how to use a yarn weight conversion chart to convert from one weight to another

If you’re looking to learn about yarn fiber types like wool, cashmere, and cotton, check out our complete guide to yarn types.

What’s In This Guide?

What Does Yarn Weight Mean?

Yarn weight refers to the thickness of the yarn you’re knitting with. All yarn is categorized by its weight, but different countries use different classification systems. In the US, yarn weight categories range from super fine to super bulky.

Despite its name, yarn weight actually has nothing to do with how heavy the yarn is. Thin yarns will be described as “light” and thick yarns will be described as “heavy” – regardless of how much these yarns actually weigh.

This thickness is the most common way of differentiating between different yarn types, and it plays a large part in determining what knitting projects the yarn is suitable for. You’ll usually find the weight category indicated on the band around the ball or skein, along with the suggested needle size.

For the best results, it’s usually safest to use the yarn weight specified in the knitting pattern you’re following. It’s possible to substitute yarns in some cases, but it’s not advisable to mix different weights in one project – this doesn’t usually turn out well!

Why Does It Matter?

The weight of the yarn you choose will make a huge difference to how your finished fabric looks and feels. It’ll also affect how long it will take for you to finish your knitting project – generally speaking, heavy yarns will knit up faster.

Certain knitting projects, textures, and fabrics require specific yarn weights to achieve a target appearance. For example, a warm blanket or winter sweater is likely to require a heavy yarn, while a sock or baby hat will call for a delicate, fine yarn. Similarly, certain types of knitting needle work best with specific kinds of yarn.

Yarn weight affects the knitting gauge (tension), and it will also affect the overall amount of yarn and the size of the needles you’ll need to complete a pattern.

In simple terms, the weight of the yarn and the yarn texture will determine the thickness of the final material. A knitting pattern that uses DK yarn will be lighter than one that uses chunky or super chunky wool. This means you can use a pattern’s suggested yarn weight to get an idea of how the final item will turn out, even before you start knitting.

If you want to avoid knitting something in the wrong size or shape, make sure you’ve chosen the right yarn and needles for the pattern. If you’re selecting patterns and materials from all over the world, it’s important to make sure you can reliably convert yarn weights between systems, too.

What Is WPI?

WPI stands for Wraps Per Inch. It refers to the number of yarn strands that can fit side-by-side within the space of an inch, and it is typically used to calculate the weight of unidentified or scrap yarn without an official label.

You can measure a yarn’s WPI by wrapping it carefully around a pencil or ruler up to three or four inches. Calculate how many strands fit in an inch without pushing the strands together or leaving gaps in between. If you’re still unsure, there are also simple WPI tools available that will do this for you.

Here’s a quick chart summarising the average WPI of each US yarn weight category:

US yarn weights and their average WPIs.
Weight CategoryWPI
Lace (0)30-40+
Super Fine (1)14-30
Fine (2)12-18
Light (3)11-15
Medium (4)9-12
Bulky (5)6-9
Super Bulky (6)5-6
Jumbo (7)1-4

What Does Ply Mean?

Knitting yarns are made of fibers. When the yarn is created, these fibers are spun from a large bundle into threads, which are twisted together to make them stronger and more durable. This twisting process is called “plying”.

A yarn’s “ply” refers to the number of threads that are twisted or “plied” together to create a single length of yarn of the desired weight. Ply count typically runs from 1-ply to 12-ply. For example, 3-ply yarn is created by twisting together three strands of yarn.

Historically, ply was used to indicate yarn weight, as thicknesses were fairly uniform. This meant that the higher the ply count, the heavier (thicker) the yarn.

However, this is no longer the case. Today, yarn ply and yarn weight do not necessarily correspond. Ply still refers to the number of threads that are twisted together, but not how thick it is.

A 5-ply might be thinner than a 2-ply, depending on how thick the threads are and how tightly they are woven together.

For example, a 4-ply yarn with thin plies might be lighter than a 1-ply yarn with thick plies. Middle-weight yarns like DK or Aran can have 15 or 20 plies in them, while single-ply yarn can be created with bulky yarn threads.

Despite these inconsistencies, some countries still use ply counts to name their yarn weight standards (even though ply and weight aren’t connected). This is particularly the case in the UK, Australia, and New Zealand.

You’ll find full yarn weight conversion instructions later on in this guide. However, as a general rule, 2-ply yarn typically equates to super-fine yarn, and 4-ply yarn equates to lightweight or DK yarn.

Below, you can find a complete explanation of the different yarn weight categories around the world.

Yarn Weight Types and Categories

assorted yarn colors
Yarn weight is classified into categories. These categories are usually labelled on the band around the yarn ball, and you’ll find them listed on the knitting patterns you’re using, too.

As with most knitting abbreviations and definitions though, there are dozens of different naming systems and standards for yarn weight categories. It’s complicated enough when you stick to one system, but things can get even more confusing once you start mixing standards from overseas.

Some countries use ply as a measurement for weight, while the USA uses numbers that have been formalised by the Craft Yarn Council of America. This means there can be confusion when knitting patterns call for a particular yarn weight.

In this section, we’ll outline the different types of yarn weight from all over the world – starting with the American Standard Weight System, and moving onto the system in the UK, Australia, and New Zealand.

Tip: There are no completely “official” yarn weight categories. However, knitting patterns across the world use some common terms to indicate a yarn’s thickness and the recommended needle size.

US Yarn Weight Categories & Standards

Most yarns sold in America have a weight number on the label. These numbers were created by the Craft Yarn Council of America and range from Lace weight (0) to Jumbo yarns (7).

These weight categories come with recommended needle sizes so you can easily match up your tools and desired projects.

These weight numbers are just a general guide, however, and it’s important to know that yarns of a particular size are not always interchangeable.

The following are the standard US yarn weight categories along with their recommended needle size and UK equivalent:

  • Weight 0 – Lace
  • Weight 1 – Super Fine
  • Weight 2 – Fine
  • Weight 3 – Light
  • Weight 4 – Medium
  • Weight 5 – Bulky
  • Weight 6 – Super Bulky
  • Weight 7 – Jumbo

Weight 0: Lace Weight

Lace weight yarn is Weight Number 0. This category is the lightest weight of yarn and covers thread, cobweb yarn, light fingering yarn, and any yarns used for lace knitting.

This type of material is typically known as 1-3ply in the UK, Australia, and New Zealand, and is commonly used to knit small, delicate items like bibs, cloths, and doilies. A good example of Lace Weight yarn is Alpaca Cloud Lace.

The fragile nature of lace weight yarn makes it prone to tangling and breakage, which means it’s not always easy for beginners. Though there isn’t a specific needle size for lace weight yarn, it is often knit on 1.5mm to 2.25mm needles to create an open, airy effect.

Weight 1: Super Fine/Fingering Yarn

Super Fine or fingering-weight yarn is weight category 1. Much like weight 0, it is often used for delicate and thin projects like shawls, socks, or baby clothes. In fact, these weight categories are so similar they are often interchangeable. If you do substitute these weight types, make sure you’re using the right needle size.

US fingering weight yarns are roughly equivalent to 4-ply yarns in the UK and Australia and are typically knit on US needle sizes 1, 2, or 3 (3-4mm). A good example of popular fingering yarn is Cascade 220 Fingering Yarn.

In the UK, super fine or fingering weight yarns (3 ply or 4ply) can also be called ‘baby’ yarns or ‘sock weight’ yarns. These terms can be useful, but they aren’t a fixed standard – sock and baby yarns can vary hugely in thickness and can equate to US weight categories 0 through to 3.

Weight 2: Fine/Sport Weight Yarn

Fine or “sport weight” yarns are US weight category 2. This yarn weight is roughly equivalent to 5 ply, though there is no direct UK equivalent. It is usually worked on US size 3-5 needles (3-25-3.75mm).

Confusingly, fine yarn can also be referred to as “baby” yarn in some countries. It’s commonly used for socks, thicker lace patterns, and baby clothes. Some knitwear designers prefer to use weight category 2 yarns over weight category 1 because it’s faster to work with and the stitches have clearer definition. A good example of fine yarn is Brava Sport.

Weight 3: DK/Light Weight Yarn

Light yarn or “DK weight” is one of the most common yarn weights in knitting thanks to its versatility. DK stands for “double knit”, a term that originated in the UK and soon spread across the world.

DK yarn is usually used for light sweaters, scarves, cardigans, hats, and other knitting patterns. It’s very close to sport weight yarn (weight 2) in thickness, but slightly heavier. It is roughly equivalent to 8 ply in Australia and New Zealand, and is usually knit on US size 6 needles (3.75-4.5mm).

In the UK, lightweight or DK yarn can also be called “Jumper Weight” yarn. Some patterns may also describe it as “light worsted” yarn due to its similarity to the next weight category up.

This yarn weight is easy for beginners to knit with and works up relatively quickly. In fact, you can even knit two threads of DK yarn together to substitute for worsted weight yarn. An example of DK or Light yarn is Sugar Baby Alpaca by Wool and the Gang.

Weight 4: Medium/Worsted/Aran Weight Yarn

Medium weight yarn is reportedly the most common yarn weight in the world. It is also known as worsted weight yarn in the US and Aran yarn in the UK. This yarn weight is lighter than bulky and super chunky yarns, but heavier than Fine and DK yarns.

Worsted weight yarns are typically knit on size 6-9 (4mm-5.5mm) needles to create sweaters, hats, scarves, and blankets. It is popular amongst all skill levels due to its excellent stitch definition and excellent ratio of knitting time to finished project.

Though the terms are often interchangeable, there is no direct UK equivalent to worsted weight yarn. US worsted weight yarn is actually slightly thinner than UK Aran yarn. However, both are roughly equivalent to 10 ply yarns in Australia and New Zealand.

In addition, ‘light worsted’ is the same as DK yarn in the UK. No wonder knitters get confused! A good example of Medium weight yarn is Feeling Good Yarn by Wool and the Gang.

Tip: In the context of yarn manufacturing, ‘worsted’ yarn can also refer to the way the yarn is processed.

Weight 5: Bulky Weight Yarn

Bulky yarns are also known as Chunky yarns in the UK and 12 ply in Australia. They are thicker than worsted weight yarns and are usually knit on US size 9-11 (5.5mm-8mm) needles for projects that require a lot of warmth and weight like bulky hats, scarves, and blankets.

Bulky yarns are ideal for beginner knitters because they’re usually knit with big, loose stitches and wide needles to finish up extremely quickly. A good example of Bulky Weight yarn is Brava Bulky.

Tip: Some yarn companies will categorize all yarns heavier than Aran or Worsted as Bulky Weight. As a result, Bulky or Chunky yarns can vary a lot in thickness and comparing or substituting them can be difficult.

Weight 6: Super Bulky Weight Yarn

Weight category 6 refers to Super Bulky Yarn. These yarns are thicker than worsted or chunky yarns and are typically worked on needles US size 11 (8mm) or wider.

Super Bulky yarns are usually used for big blankets, heavy sweaters, rugs, and bulky hat knitting patterns. The final outcome is usually super warm and can be knit up in a single afternoon.

Super Bulky yarns are also known as Super Chunky yarns in the UK, and 14 ply in Australia and New Zealand. A good example of super bulky yarn is Crazy Sexy Wool by Wool and the Gang.

Weight 7: Jumbo/Roving Weight Yarn

Weight Category 7 is the thickest yarn weight category. It refers to Jumbo Weight yarn that is usually used for heavy blankets, rugs, and arm knitting projects.

Due to its weight and thickness, Jumbo yarn is usually knit using US Size 17 (12.75mm) needles or larger. A popular example is jumbo yarn from Lauren Aston Designs.

UK, Australia, and New Zealand Yarn Weights and Standards

Now we’ve covered the standard US yarn weight categories, here are the most common names of yarn weights in the UK and their rough US equivalents. You can find out the needles each yarn weight is commonly knit with, as well as the projects they’re usually used for.

Remember, if you’re looking for a quick yarn weight conversion, skip to our yarn weight conversion table.

1 – 3 Ply

1, 2, and 3 ply yarns are roughly equivalent to Lace Weight (0) yarns in the US. They’re usually knit on 1.5mm to 2.25mm needles for delicate socks, baby clothes, and lace patterns.

4 Ply

4 ply yarns are roughly equal to Super Fine or Fingering Weight (1) yarns in the US. This yarn weight is also used to knit lightweight baby clothes, socks, and tops on 3mm to 4mm needles.

Double Knitting (DK)

In the UK, DK yarns are approximately equivalent to Fine (2) or Light Weight (3) Yarns in the US. It is usually double the thickness of 4 ply yarn and knit on 3.5mm to 4.5mm needles.

Aran

Aran weight yarn is equivalent to Medium/Worsted Weight (4) yarns in the US. It is used for midweight projects like jumpers, scarves, and thicker tops on 4mm to 5.5mm needles.

Chunky

UK Chunky yarns are roughly equal to Bulky Weight (5) yarns in the US. They are used for oversized projects, cropped chunky sweaters, and other warm garments on 5.5mm to 7mm needles.

Super Chunky

In the UK, Super Chunky weight is around the same as Super Bulky (6) Weight in the US. It is great for beginner projects and heavy patterns like blankets on 7mm to 12mm needles.

Big

Big UK yarns are roughly equivalent to Jumbo Yarns (7) in the US. It is the thickest yarn weight
category available, and is typically knit on 9mm to 20mm needles for super-thick throws, rugs, scarves, and coats.

Yarn Weight Conversion and Comparison

These weight categories can be helpful signposts when choosing yarn for your next projects. But within all of those categories there are dozens of light and heavy variances. For example, you can find light worsted yarn, medium worsted weight, and even heavy worsted weight.

If none of these labels are official, how can you ever be sure you have the right size yarn? What if you’ve discovered some unidentified yarn and you need to know how heavy it is, and what needles to use?

In this section, we’ll talk about comparing and calculating yarn weights using yardage, meterage, and WPI.

Comparing Yarn Weights by Yards/Meters

In our curated knitting patterns, you’ll often find recommended yarn weights listed by their grams to yards ratio, or grams to meters. For example, we might list the recommended yarn weight as 80m = 200g.

This is an objective metric that lets you find out exactly how heavy the yarn needs to be, regardless of its weight category. When buying your yarn, you can work out exactly which yarn to choose and how much of it you need based on how heavy each ball or skein is and how many meters or yards of yarn are included.

To compare yarn weights by yardage or meters, simply look at the label to find the weight and length. If one ball of yarn is 200 yards long and weighs 50g, it will be significantly thicker than another ball that is 300 yards long and weighs the same amount.

If you’re trying to compare or match yarns, you should try to find yarns with a yardage:weight ratio as similar as possible.

In this table, we’ll outline the average yards per 100g for each US yarn weight category. If you’re choosing a yarn for a pattern, figure out how many yards per gram the pattern requires and use the table to see what category of yarn weight it is in and how heavy it is. Then you can find a yarn that fits.

The average yards per 100g for each yarn weight category.
Weight CategoryYards per 100g
Lace (0)500-1000
Super Fine (1)380-500
Fine (2)300-380
Light (3)220-300
Medium (4)190-240
Bulky (5)100-140
Super Bulky (6)40-100
Jumbo (7)5-40

Once you’ve found your ideal yarn weight, you can convert it to the standards you need in the yarn weight conversion chart at the end of this article.

How to Calculate Yarn Weight Using WPI

You can also use WPI (wraps per inch) to calculate which yarn weight category your supplies fit into. All you’ll need is a ruler, a knitting needle, or a pen.

measuring WPI with a ruler
You can use a ruler to measure WPI.

To calculate yarn weight using WPI:

  1. Carefully wrap your yarn around a pen or knitting needle for 2 or 3 inches.
  2. Ensure the yarn is wrapped tightly without any gaps or overlapping threads.
  3. Measure 1 inch (2.5cm) and count the number of yarn wraps that fit in that space.
  4. Repeat this in one or two different places to ensure you have an accurate reading.
  5. Use the yarn weight conversion chart to compare the measured WPI to US yarn weight categories.

Yarn Weight Conversion Chart

The yarn weight chart below contains everything you need to compare and convert yarn weights across different international standards and measurements.

You’ll find each US yarn weight category along with its UK equivalent, ply count, WPI count, yards per 100g and recommended needle size. We’ve also listed the knitting patterns and projects each yarn weight is typically used for.

Use this chart to choose the right yarn for your project, compare and convert yarn weights, and substitute yarns across different international categories.

Yarn weights and their international equivalents.
US Yarn WeightUK Yarn WeightAU Yarn WeightCommon NamesWPIYards per 100gMeters per 100gNeedle Size (mm)Knitting Projects
Lace (0)1 Ply2 PlyThread, Cobweb, Fingering30-40+500-1000600-11001.25mm-3mmLace knitting, cloths, doilies
Super Fine (1)2 Ply3 PlyFingering, Sock, Baby14-30380-500420-5801.25mm-3.5mmShawls, socks, baby clothes
Fine (2)4 Ply5 PlySport, Baby12-18300-380260-4003.25mm-4mmSocks, light sweaters
Light (3)DK8 PlyJumper, Light Worsted11-15220-300210-2504mm-5mmLight sweaters, scarves, tops
Medium (4)Aran10 PlyWorsted, Afghan9-12190-240130-2004.5mm-6mmHeavy sweaters, hats, scarves
Bulky (5)Chunky12-14 PlyHeavy Worsted, Craft, Rug6-9100-14090-1205mm-8mmBlankets, sweaters, chunky hats
Super Bulky (6)Super Chunky16 PlyRoving5-640-10040-808mm-12mmRugs, jackets, blankets
Jumbo (7)Super Chunky20 PlyRoving1-45-4035-7012mm+Heavy blankets, rugs, arm knitting

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