If you find yourself asking, “What’s a tension square?”, then you should read this article.
Or, if you find yourself asking, “Do I really have to do a tension square everytime?”, then you should probably read this too.
Of course, you can skip the tension square completely if you wish. If you don’t mind running the risk that the hours of labour you put into knitting yourself a new sweater will result in you giving that sweater to your sister, who is two sizes smaller than you, because it didn’t quite come out the size it said it would on the pattern.
It may feel like a whole evening is devoted to knitting nothing more than a square, which you are then going to pull out afterwards anyway. You could have started knitting your new sweater instead. What a waste! But, it’s important to know that the tension you are knitting at is the same as your pattern asks for, so that your garment does in fact come out the right size. It’s probably going to take you weeks, if not months to make it, so what’s one more evening before you start?
Every pattern should have the tension requirements on it. These will be written something like this:
TENSION – 22sts and 28 rows to 10cm, (4inch), over stocking stitch on 4.0mm needles.
So, if you knit a square which is 10cm x 10cm, with 4.0mm needles, in the yarn used in the pattern, then when you have a closer look at this square, you should have 22sts in a row and 28 rows . But, we all knit slightly differently, some tighter, some looser. If you knit a little bit tighter you will have more stitches and rows in your 10cm square. Whereas, if you knit a little bit looser then you will have less stitches and rows in your square.
Let’s start by working out how to do the tension square.
We will assume that we are trying to knit a tension square to match the pattern above.
Start by casting on the number of stitches expected in the tension square, plus a few. Perhaps cast on 30sts. Then knit in stocking stitch, (knit a row, purl a row), until your work measures at least 12cm.
We are making the tension square slightly larger than the 10cm square required, so that we are not trying to count the edge stitches, but instead a nice flat square of stitches.
Once you have knitted your square, pin it out flat, but do not stretch the fabric.
Each little V shape is a stitch and it is these we will be counting.
With two more pins and a tape measure or ruler mark out 10cm, across one horizontal row of stitches. This can be anywhere on your square.
Then count the number of stitches between your two pins. (Count the number of Vs)
In this case there are 22 stitches.
Then move your two pins and mark out another 10cm, but this time up one vertical line of stitches.
Count the number of stitches again between the two pins. This gives you the number of rows.
In this case there are 31 rows.
Once you have measured the number of stitches and rows from your tension square you then need to compare it to the pattern.
If you have too many stitches, your knitting is a little bit tight, so you will need to use a larger needle size to achieve the correct tension.
If you have too few stitches then your knitting is too loose, so you will need to use a smaller needle size.
The bad news here is that if you need to use a different needle size then really you should knit another tension square using what you think will be the correct size needle and then measure again to make sure it is going to work. Try going up or down a size, say from 4mm down to 3.75mm if you knit too loose, or up to 4.5mm if you knit too tight.
It is often unlikely that you will manage to get the correct number of stitches and rows in your tension square both at the same time. Usually it is considered better to have the correct number of stitches rather than rows, as the length of something is much easier to adjust than the width. For example, in my tension square above, there are exactly 22sts per 10cm, but 31 rows (I have an extra 3 rows). So, I would use a 4mm needle as the pattern suggests because the stitches are correct, but I am aware that I may need to knit extra rows in places to prevent the garment being too short.
Once you become an experienced knitter you may find that you don’t feel the need to knit a tension square very often. You will come to know what your own knitting tension is like and think you know what you are doing. I would still recommend that every now and again you do a square and check your tension. Things change over time, our hands get older, our eyes get weaker and things don’t always work the way they used to! Plus, different yarns can give different results sometimes too, even if they claim to be of the same thickness. If you are substituting different yarns into a pattern than those the pattern was written for then a tension square is almost definitely a must!
It’s your choice. Knit the square or risk it? I’ll let you decide…