Knitting tension squares: what to do and why to do it

Knitting a tension square to check your gauge is a sure-fire way to create knits that’ll fit you like a glove. In this tutorial we show you how it's done.

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Knitting tension square

You may have heard how important knitting tension squares is to getting the best result from your pattern, but exactly what is tension and why do you need to check it? In this article we’ll show you that knitting tension squares is easy, and well worth the effort! We’ll cover:

What is tension (gauge)?

To achieve great results from your knitting it’s important to ensure that you have the correct tension (also known as gauge). Tension is how many stitches and rows can be found in a square of knitted fabric, typically one measuring 10x10cm (4x4in). For your finished project to turn out like the one in your pattern, your tension needs to match the tension given in the instructions.

The tension you need to knit to is governed by your yarn weight and needle size, and is usually stated in the knitting pattern and on the yarn’s ball band. In our patterns you’ll see it written like this:

“Yarn used knits as DK to this tension: 22 sts and 28 rows to measure 10x10cm (4x4in) over stocking stitch using 3¼mm needles”

How loosely or tightly you knit will determine the tension of the fabric you produce. Everybody’s tension is different, and it can also vary for one person from project to project. You may find you knit more tightly with wooden needles, for example, or knit more loosely if you’re learning how to do Continental knitting. Since you might not have the same tension as the person who designed the pattern you’re following, it’s crucial that you check how yours matches up every time you cast on something new.

So, before starting any project, it’s a good idea to knit a small square with the yarn you’re going to use. This is called a tension square. Some knitters see knitting tension squares as a chore, but it’s an important step that it’s best not to skip – particularly if you’re making a garment that you want to fit well and look fantastic. If your tension is too tight, your garment will come up smaller or shorter and might not fit you properly; if your tension is too loose, you’ll find that the garment is too baggy.

How to make and use a knitting tension square

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Step 1

Knit the tension square

Knitting tension square swatch
Knit a tension square with the yarn you’re going to use for your project.

To make a square to check your tension or gauge, use the yarn and size of needles that the pattern states. The pattern will also tell you what stitch to use – this is often stocking stitch, but may instead be a decorative stitch pattern used in the design. Most often, you’ll find that the instructions given are for a 10x10cm (4x4in) square, but to correctly measure your tension, we recommend that you make a square at least 15x15cm (6x6in) in size. (Try using the number of stitches stated in the pattern tension, plus half again.) If you’re working in stocking stitch you might also want to include a garter stitch border to prevent it from rolling and make measuring easier.

If you are intending to block your garment when it’s finished you may also want to wash and block your tension square before you measure it, to give you the most accurate results. Some fabrics can change a lot in size when they’re blocked! Find out more about this process in our essential guide on how to block knitting projects.

When you’ve completed the square, pin it to a padded surface (such as a firm cushion), and gently smooth it out, being careful that you don’t distort the stitches.

Step 2

Check your stitch tension

Knitting tension square stitch tension
Calculate the stitch tension by measuring across your knitting tension square.

To work out the stitch tension, use a pin as a marker and insert it vertically between two stitches. Then, using a rigid ruler, horizontally measure 10cm (4in) and place another pin in the fabric. Count the number of stitches between the two pins. If your tension corresponds with that given in the pattern you can start knitting.

However, if you have more stitches than is stated in the pattern’s tension guide, it means that your knitting is too tight; try making another square knitted on needles that are one size bigger. If you have fewer stitches than is stated in the pattern’s tension guide, then your tension is too loose, so try knitting another square on smaller needles.

Continue increasing and decreasing needle sizes until you get as close as possible to the tension stated in the pattern.

Step 3

Check your row tension

Knitting tension square row tension
Calculate the row tension by measuring down your knitting tension square.

To check row tension, horizontally insert a pin and measure 10cm (4in) vertically and insert another pin. Count the rows between pins and if they correspond with the pattern, your row tension is fine. If there are more or fewer rows, use smaller or larger needles to create another square.

If the row tension is only slightly out (such as half a row to one row), it shouldn’t make too much difference to the final garment, especially because most patterns instruct you to knit the piece to a certain length.

When you’re happy that your stitch and row tensions are close enough to the pattern’s, you’re ready to cast on.

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3 knitting swatch rulers to buy

As well as checking your needle sizes, some needle gauges also come with a handy ruler for checking the measurements of your tension squares. Here are three of our favourites…

1. ChiaoGoo Needle and Swatch Gauge

Knitting needle gauge ChiaoGoo

This all-in-one gauge from ChiaoGoo can measure needles and swatches in US and metric sizes, and it also has a needle conversion chart and guide to the different types of yarn with their recommended tension and needle size. Plus did we mention it has all the info you need for crochet too?

Buy it now from Etsy.

2. Clover Swatch Ruler and Needle Gauge

Knitting needle gauge Clover

The 4x4in window in this swatch ruler from Clover is the perfect size for measuring your tension squares, and makes it easy to count your rows and stitches by isolating the section of fabric you need. If that wasn’t enough, you can also measure your needles (and hooks) in metric, US and Japanese sizes.

Buy it now from Amazon.

3. KnitPro Elephant Needle Gauge

Knitting needle gauge KnitPro

Check the size of your swatch using the window in this fun elephant-shaped needle gauge from KnitPro. It also has a built-in yarn cutter, handy for finishing swatches on the go, and can be used to check the sizes of your knitting needles and crochet hooks. The gauge comes in two colours, lilac and blush pink.

Buy it now from Ebay.

Other uses for tension squares

You can use a tension square if you have an old pattern that was intended for a now discontinued yarn and you want to make up the garment in a yarn of the same weight, or you simply want to substitute the yarn used in the pattern. For example, if you want to make a DK jumper, buy a similar DK yarn and work tension squares until you get the tension stated in the pattern.

Swatches are also useful to test how a yarn washes. Does it stretch after washing, and does the dye bleed? Is it safe in the washing machine or will it felt? All these things are useful to know before you cast on, and knitting tension squares can help you find out.

What should you do with your finished squares? We recommend keeping them. They can be handy to unravel for finishing off if you run out of yarn, or you can store them in a folder or knitting journal to record how a yarn knits up, in case you want to use it again. Just remember to pin a ball band or label to each swatch, so you know which one is which!

Tension squares project idea

Why not knit up a collection of tension squares to make a stitch sampler blanket? We have loads of stitch patterns for you to try, including moss stitch, rib stitch and lace knitting stitches, plus beautiful cables in our guide on how to cable knit.

How to cable knit