How to knit a gauge swatch (and why you should!)

We’re excited to have Allison and Rachel from Yarn in the City writing some yarn-focused blog posts for us to help inspire you with your knitting and crochet projects. This edition is all about swatching, what is is and why it is a good thing to do. Take it away ladies…

how to knit a gauge swatch

Do I really have to swatch?

Who among us hasn’t asked this question at one time or another? You’re in the grips of the excitement of starting a new project, and you just want to get going! But then come those dreaded phrases – “adjust needle size as needed to get gauge”, “please swatch to ensure adequate yarn,” “swatch to avoid disappointment.” Argh!

Even though we are firmly in the camp of Swatching Is Good, we still get frustrated by having to pause in my casting on frenzy to knit a square, block it, wait for it to dry, measure it, and repeat ad infinitum until I get the correct gauge. But it is true that swatching is important, and there is a right way to swatch. There are also a number of factors that play a big role in whether or not your swatch tells the truth.

Why Swatching is a Good Thing by Allison and Rachel from Yarn in the City!

Why swatching is important:

You certainly don’t have to swatch – there are no swatching police! But if you want your project to end up the correct size and match the schematic measurements, swatching is a critical part of the process. Don’t do what Rachel did and spend several months in uni knitting an entire cabled sweater without swatching only to discover that the finished object fit her with 40 cm of ease! Particularly if you are starting a project for which fit is essential (jumpers or socks), swatching can save you hours of wasted time, additional expense and considerable heartbreak!

Why Swatching is a Good Thing by Allison and Rachel from Yarn in the City!

How to swatch correctly:

There’s no gold standard for how to swatch, but there are some general guidelines. Be sure you make your swatch big enough! The minimum size for a swatch is about 10 x 10 cm, but I’d definitely recommend making one bigger then that if you can stand it.
Work a garter stitch border around your swatch so it will lie flat when it’s finished. For all the swatches pictured below I cast on 26 sts and worked the first and last three stitches of each row in garter stitch, with 6 rows of garter stitch to start and finish.

If your project is knit in the round, you should swatch in the round. You don’t actually have to work a tube – use circular or double pointed needles, cast on and work one row. Slide the work to the other end of the needle and work the next row, leaving a long float across the back of the swatch so there’s plenty of room for it to lay flat when you’re done. Keep going until the swatch is the size you want, bind off, and block. You can cut the floats if you like, but just be sure to fasten them off so that the stitches are even along the edges.

Also make sure to treat your swatch as you are going to treat your finished project. Block the swatch in the same way as the final project, and let it dry before measuring the gauge.

To measure the gauge lay the swatch flat without stretching or pulling. Take a ruler or a measuring tape and lay it across the portion of your swatch between the garter edges. Measure this section and then divide it by the number of sts in the swatch (not counting the edges). Do the same for the row measurement. Then you can extrapolate to sts/rows per inch/cm.
Why Swatching is a Good Thing by Allison and Rachel from Yarn in the City!

A word about interpreting measurements: swatches with looser gauge will have fewer stitches or rows per unit measure. Swatches with tighter gauges will have more stitches or rows per unit measure.

OK, let’s take a look at some factors that will affect your gauge and how those factors can be used to your advantage.

Stitch pattern:

This may seem completely obvious, but the stitch pattern that you use for your swatch will affect your gauge dramatically. Case in point: the three swatches below were all knit on the same needles with the same number of stitches cast on and the same number of rows. They were all blocked the same way.

Why Swatching is a Good Thing by Allison and Rachel from Yarn in the City!

You can see that the cables pull the fabric in dramatically, while lace patterns open the fabric up and give fewer stitches per cm.


The type of needles you use couldimpact your gauge. The four swatches below were all knit with 5.0 mm needles of different materials. One swatch was knit on metal needles, one was knit on plastic needles, and two were knitwith wooden needles – one set smooth and polished, the other set rough. All swatches were worked over the same number of stitches for the same number of rows, and were blocked the same way.

Why Swatching is a Good Thing by Allison and Rachel from Yarn in the City!

Here’s how the gauge came out: Metal needles: 16 sts/22 rows per 10 cm; plastic needles 22 sts/23 rows per 10 cm, smooth wooden needles: 18 sts/25 rows per 10 cm; rough wooden needles: 16 sts/ 24 rows per 10 cm.
The plastic needles gave the tightest stitch gauge, while the metal and rough wooden needles gave the loosest stitch gauge. Metal and plastic needles gave similar row gauges, while wooden needles had looser row gauges. Generally speaking, smoother needles will give tighter gauges, while rougher needles will hold on to the yarn and give a looser fabric at the same needle size.
The take home message from this experiment is that if you are swatching and having trouble getting correct gauge, but changing needle size is too much of a difference, try a different type of needle.

Yarn choice:

The yarn you choose for your project plays an integral role in how successful you’ll be. The first thing to consider is the yarn weight – all knitting patterns should indicate the weight of the yarn used. Sometimes that will be explicit and sometimes you need to do a bit of digging, particularly if you are going substitut a different yarn. If the weight isn’t given in the pattern, look up the yarn called for on Ravelry, which will tell you the yarn weight.

Another clue is the gauge: if there are more stitches listed in the gauge over 4 inches/10 cm, the yarn is finer. For example, a project worked at a gauge of 32 sts over 4 inches/10 cm (a 4-ply gauge) uses a finer yarn than a project worked at 12 sts over 4 inches/10 cm (super chunky gauge).

On other thing to keep in mind: the terms used to indicate yarn weights vary regionally, and the name for a particular weight of yarn in one part of the world may refer to a completely different weight of yarn somewhere else! To help you navigate this tricky area, we’ve included a table comparing US, UK and Australian names for different weights of yarn, along with the approximate stitch gauges for each weight.

US UK Australia Gauge over 4 inches/10 cm
Laceweight 1 ply
2 ply 2 ply 32-40 sts on 1.5 – 2.25 mm needles
Fingering 4 ply 3 ply 27 -32 sts on 2.25 – 3.25 mm needles
Sport – 5 ply 24-27 sts on 3.25 – 3.75 mm needles
DK/Light worsted DK 8 ply 21-24 sts on 3.75 – 4mm needles
Worsted Aran 10 ply 16-20 sts on 4.5-5.5 mm
Bulky Chunky 12 ply 12-16 sts on 5.5 -8 mm needles
Super Bulky Super Chunky 14 ply Anything less than 12 sts per 4 inches/10 cm

Finally, your fibre choice can affect your project, particularly if you are substituting yarns. A general rule of thumb is to try and match the fibre content (I.e. wool for wool, cotton for cotton) and the meterage.

Be aware that some fibres change more after blocking than others, particularly superwash wools, which can grow dramatically after they get wet, leading to much looser gauges than you want or need! The swatches below were all knit out of the same superwash wool, but were blocked differently: the left swatch wasn’t left unblocked, the middle swatch was wet blocked and air dried and the right swatch was wet blocked and tumble dried. Air drying resulted in a larger swatch than the unblocked version, while tumble drying produced a smaller swatch.

Why Swatching is a Good Thing by Allison and Rachel from Yarn in the City!

Hopefully these tips are enough to get you started on your swatching adventures. Happy knitting!

Thanks Ladies!

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