What is a tension square – and why is it so important for your knit or crochet projects?

Successfully knitting and crocheting garments is one part yarn, one part passion, one part patience...and one part tension!  

So what is a Tension Square? Why should you make a tension square? How do you do a tension square?  

Let’s answer these important questions, or: JUMP TO THE INSTRUCTIONS

Put simply, a Tension Square is a knitted or crochet sample., created specifically to make sure YOUR stitches are the same size as what the pattern requires You may also have heard them referred to as a swatch or a gauge sample. Importantly, your tension square is knit or crocheted in the pattern of the item that you are about to knit/crochet: stocking stitch, lace, treble crochet or whatever it is that your pattern specifies. 

Usually, a tension square is a 12-14cm square: 10cm of knitting/crocheting in pattern with 1-2cm on either edge (to make it easier to count the stitches in the 10 cm section without your square curling up). 

Tension squares are valuable, particularly if you’re making a garment that you want to fit! Many novice and experienced knitters and crocheters skip this step because they want to dive right into their projects. We get this, crafty ones – BUT before you spend 50+ hours on a garment, why not spend 1-2 hours and be sure your finished item is likely to be the size and fit you want? 

Same knitter, same needle size, but different yarns - and look how different the size has come out! Lucky Kai did a tension square before embarking on this project!

Let’s talk tension 

Tension (or gauge) is really a description of how tight or loose your knitted or crocheted stitches are. This will vary based on yarn, needles and your own personal style. 

The majority of patterns available will list a tension you are aiming to achieve. There is stitch tension and row tension.  

Stitch tension is based on stitches (the width of each stitch) and Row tension is based on rows (the height of each row). While is important to try and match both to ensure that your item will fit, many patterns have you knitting to a measurement, rather than a certain number of rows, which makes it easier to adjust for row tension. Many patterns don’t list row tension for this reason so don’t be alarmed.  

For the item in the pattern to turn out to the correct size, as specified in the pattern, you need to make sure you are knitting/crocheting “to tension”. This is essential for garments, beanies and any item that needs to be a specific size to fit/not fall off. It also helps ensure that you have the right amount of yarn for your project – yarn requirements are based off samples knit/crocheted to the specified tension, so if yours is different you will use more or less yarn.  

Do I really need to do a Tension Square?  

Yes – for anything that is required to “fit” like a jumper, beanie, or socks. For blankets and shawls it’s not as important, but if you aren’t getting tension you may use more or less yarn than stated in the pattern.

Now that being said, there are no craft police – no one is going to bang on your door and tell you off for not doing a tension square.  And with practice, you will become familiar with your own knitting/crochet style and be able to make an educated guess as to whether your tension will be appropriate for a pattern.

Just be aware that doing a tension square is always a good idea to help you make a more informed choice before embarking on your project.  

Another reason to do a Tension Square - checking fabric properties: 

When you are using a different yarn to what a pattern recommends, doing a tension square is vital to check that you're able to meet the required tension, but also to confirm that the fabric you are creating matches what the pattern requires and your personal preferences. 

For example, you might be wondering ‘can I make this tee shirt pattern in an 8 ply wool yarn instead of the cotton blend it specifies?’. But a wool yarn and a cotton yarn have different properties and will result in a different fabric. Making a tension square using your desired wool yarn will help ensure that your final garment has the drape and flow that you expect – if your fabric is thick and inflexible at the required tension then perhaps your yarn choice needs to be reconsidered.  

Here’s an example of how tension is commonly referenced in a pattern. 

Tension as specified in one of our patterns: this is saying that there should be 22 stitches in every 10cm section when your knitting is in stocking stitch using the recommended 4.50mm needles. Row tension is not specified so you don’t need to check that in this case.

How does that work out over a project? If the stitch tension is 22sts to 10cm, it means to get an item that is 100cm across you need to cast on 220 sts. However, if you are getting 21sts to 10cm, and knit your item in that tension, it means that it will come out at 105cm across – a whole size bigger!  

If you are knitting a fitted garment without much room for movement, having less sts to 10cm in your tension means it will have a looser fit than intended. Alternatively, if you have more sts to 10cm in your tension, that garment may not fit at all or at least be too tight to be comfortable.  

So how do you adjust to get the right tension?  

To change your stitches to match the required tension, you'll need to adjust your needle or hook size up or down. If you have too many stitches in your square, you need to try a slightly larger needle: for example you get 24 stitches to 10cm when using 3.75mm needles, and the pattern requires 22 stitches, you might be better off using 4.00mm needles. If your stitches are too big and you’re getting fewer stitches than the pattern requires, try reducing the size of the hook/needle. 

Some things to keep in mind.  

• Go bigger: Even though tension is measured at 10cm by 10cm you will want to prepare a much larger swatch to try and get the most accurate tension.  

• Swatch in the same construction: If the item you are making is worked in the round you want to work your swatch in the round.  

• Wash your swatch: We recommend that you measure your swatch and take your tension, and then launder your swatch in the same manner as you would the finished item and then retake your measurements. This is particularly important for yarns that don’t have the same elasticity as Wool, like Alpaca and Cotton. Some people find that their tension looks great before washing, but after the yarn has relaxed in the wash, it 'grows' and the tension no longer matches.
  

• Swatch in the same stitch/pattern: You should do the tension square in the stitch/pattern that the item is being knitted. The pattern will usually specify 'stocking stitch' or 'over pattern'.  A lace pattern will have different tension to stocking stitch, and so your tension square won't count if you knit it in stocking stitch!
  

The peril of an incorrect swatch - a cautionary tale from one of the BWM team.

Not long after I re-taught myself to knit in my mid-twenties. I found a pattern that I wanted to make. I did the tension square in stocking stitch. I bought the wool including some extra balls just in case! Then I found I needed to purchase another 10 balls (these were 50g balls) and possibly another 6 after that. It wasn’t until I’d finished it and tried it on that I realised how much bigger it was than it should be (yes lessons about measuring when you knit). It was then I realised I needed to do the tension square in the specified pattern not in stocking stitch.  

How to knit or crochet a tension square: 

This example is for a pattern that specifies a tension of 22 stitches per 10cm using 4.00mm needles and working in stocking stitch. You’ll need your yarn, needles, a ruler or measuring tape, and a flat surface. Pins are also helpful here.  

Creating the swatch:

• Cast on at least 26 stitches using 4.00mm needles. 
• Knit each right-side row and purl each wrong side row (stocking stitch) until your work measures at least 12cm long including the cast-on edge. 
• Cast your work off.

Measuring the swatch:

• Lay the square flat, without stretching it. You may find it easiest to pin it to a firm surface like a sofa cushion or an ironing board. 
• Use a ruler to measure a 10cm section of your swatch.
• Count how many stitches fit into that 10 cm (4 inch) section. If you count 22 stitches in a 10cm long segment, you’ve matched the stitch tension specified in your pattern. If not, you'll need to adjust your tension.
  
• If your pattern specifies a row tension, do the same thing by counting the number of rows in a vertical 10cm area. 

In this example we’re working with a finished garment but the same principles apply. We’ve laid the garment flat, measured out a 10cm length with our ruler, and put pins at each end of the 10cm section, then counted the number of stitches between the pins (stitch tension). We then do the same for rows, measuring vertically instead.  

When you understand tension and gauge and the mathematics behind it, you'll be much more likely to be happy with the fit and feel of your final project. We wish you all the best on your next creative project!