How to Select and Use Yarn

Published March 11, 2016 by estherknit

Yarn is a term used for any type of thread used as knitting material no matter how it is made. Many yarns belong to groups according to their construction.

Ball of Wool 1When you have chosen your knitting pattern, then you need to choose the right yarn for your project. The knitting pattern will suggest a yarn (or two) which will work for the project. However, you may not want to use the suggested yarn. With a seemingly endless choice of yarns, and patterns, the novice knitter may find the choice overwhelming.

The yarn label

You will find information about the yarn on the label. This usually includes fibre content, weight and care instructions. You should also find the recommended tension and needle size included.

Dye lots

The colour information will also include a dye lot number. Wool is dyed in batches and each one can vary slightly, so it’s a good idea to buy all the wool you will need for your project together, to ensure the colour matches. The colour in different dye lots can vary quite drastically and it is advisable to see that you have plenty of yarn in the same dye lot to complete your project.


Yarn also comes in different thicknesses as well as weights. Yarn can be made up of a single strand of fibre but often it includes a number of strands twisted together. Thicker yarns are made of more tightly spun strands, rather than more strands twisted together.

All yarns of the same ply are not necessarily the same thickness. Some soft Shetland 2 plys are thicker than a fine 3 or 4 ply.

How is the yarn wound

The yarn can come as a

  • hank : these will need to be wound into a ball before knitting
  • skein : wound up into an oblong shape, pull the yarn from the inside, not the outside
  • ball: wound into a ball, use the end of the yarn on the outside. most hand knitting yarn comes as a ball
  • cone: most machine knitting yarn comes in conesCone


Check the weight of the yarn you are buying. Balls of yarn can be 20, 25, 40, 50 and 100 grams. Make sure that the total weight of yarn you buy is sufficient rather than relying on the number of balls stated in your pattern.

Finding the right yarn for your project depends on

  • the knitting pattern you have chosen
  • the needles you will use for your project
  • the effect you want to create

Yarn classification

  • Baby: wool designed for babies is less fluffy, which helps stop the fibres going in their mouth. They are generally lightweight, delicate and soft on young skin.
  • 2/3 Ply: this refers to the number of strands twisted together. Use for projects where accuracy is important, such as gloves or socks
  • 4 Ply: good for baby clothes or lacy garments. Also known as Sport
  • Double Knitting (DK): the most versatile and widely used yarn, it’s called DK as it’s double the weight of 4 Ply yarn. Suitable for all kinds of garments. Sometimes referred to as Light Worsted
  • Aran: named after traditional knitting from the Aran Isles, it’s ideal for chunky jumpers. Also known as Fisherman
  • Chunky: chunkier styles create quicker, thicker knits, so they’re a good choice for beginners. Sometimes known as Bulky, they make cosy jumpers and outerwear, perfect for cold weather. However the bulky styles you create may be too hot for babies and are not suitable for warm weather wear
  • Super Chunky: A great yarn for quick knitting. Also known as Super Bulky
  • Fashion: These more unusual yarns will create unique projects, such as fashion scarves.


If you do not have yarn of the correct thickness for your project, you can strand up the yarn – that it knit two or three strands of yarn together to make a thicker yarn. Here is a guide.

  • to make a 4 ply yarn, take two strands of 2 ply, or three strands of 2/30s machine knitting yarn
  • to make a double knitting yarn, take 2 strands of 4 ply yarn
  • to make a chunky yarn, take 2 strands of double knitting yarn
  • to make a super chunky yarn, take 3 strands of double knitting yarn.

Remember, if you use a different yarn to the one in the pattern, then you will need to knit a tension square (gauge swatch) and measure your tension before you start your project.

How to calculate how much yarn

If you want to know how much yarn you have to use, e.g. for a sweater, you must take some of the yarn, make a sample and find the area in cm2. Weigh it on a letter-balance. Divide the weight in grams by the number of cm2 to get the weight per cm2. The result will be 0.0…something grams.

Now, assume your sample measures 14.6 cm × 15 cm. Multiplying width with length gives us 219 cm2. Now, weigh the sample, e.g. 6 grams. Now, divide the weight by the area:

6 g / 219 cm2 = 0.027 g per cm2.

To find the area of the sweater, calculate the area of the body by multiplying the circumference by the back length. To find the area of the sleeves, measure the upper arm circumference and multiply by the arm length from shoulder to wrist. Add the two calculated areas, and you have the estimated area for the sweater. Now multiply the sweater area by the weight per cm2 and this tells you how many grams of yarn you need.

For example, if we have some yarn and want to know if there is enough for a child’s sweater. The chest circumference is 68 cm and the length of the sweater is 39 cm.

68 cm × 39 cm = 2652 cm2.

The upper arm circumference is 28 cm, and the sleeve length is 37 cm.

28 cm × 37 cm = 1036 cm2.

The body area 2652 cm2 + the sleeve area 1036 cm2 = 3688 cm2. Weight per cm2 is 0.027 g.

0.027 g × 3688 cm2 = 99.5 g.

This means that we need 2 balls of 50 g each. So, I would buy 3 50 g balls for this sweater to make sure that you have enough yarn.



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