How to calculate knitting gauge – swatching, stitches per 10 cm and adjusting a pattern

Gauge is the most boring and at the same time the most important step before you cast on a garment. It decides whether the hat fits as it should, whether the sweater comes out the right size and whether your pattern gets the proportions you had in mind. Here we go through how to knit a swatch, how to measure it and how to use the numbers – including when you design your own pattern.

What is gauge?

Gauge (called tension in the UK) tells you how many stitches and rows fit into a certain distance, almost always per 10 cm (4 in). A pattern might say, for example:

24 stitches and 30 rows in stockinette stitch on 3.5 mm needles = 10 × 10 cm.

The needle size is only a recommendation. What matters is that your knitting gives the right number of stitches per 10 cm. Two people with the same yarn and the same needles can get completely different gauges, because everyone holds the yarn with a different tension.

Knitting a swatch

Size

Knit a swatch that is larger than 10 × 10 cm, ideally at least 15 × 15 cm. The stitches nearest the edges are often uneven, so you want to be able to measure a clean area in the middle.

If the pattern says 24 stitches per 10 cm, cast on about 36 stitches.

Knit it the same way as the garment

The swatch should be knitted the way the garment will be knitted:

• The same technique. Colourwork almost always gives a different gauge from plain stockinette, often tighter. If the garment is in colourwork, knit the swatch in the pattern.
• In the round or flat. Many knitters purl a little looser or tighter than they knit, so a swatch knitted flat can give different measurements from one knitted in the round. For a garment knitted in the round, you can knit the swatch in the round, as a small tube, or knit “right-side rows only” on a circular or double-pointed needle: knit a row, slide the stitches back to the other end of the needle, carry the yarn loosely across the back and knit the next row from the right side again. Cut the tube open or leave the long strands at the back hanging loose.
• The same yarn and needles – ideally the exact needles you will use, since the material (wood, metal) can also make a difference.

Wash the swatch

Treat the swatch like the finished garment: wash or soak it according to the yarn’s care instructions and let it dry flat. Wool can “grow” or shrink slightly, and colourwork evens out with blocking. Only measure once it is completely dry.

Measuring and counting

Lay the swatch flat without stretching it. Use a ruler or a gauge ruler (a small frame with a 10 cm window).

Method 1: count across exactly 10 cm

Count how many stitches fit into 10 cm in the middle of the swatch. Don’t forget half stitches – they matter across a whole garment. Do the same vertically for the rows. Ideally measure in two or three places and take an average.

Method 2: measure a known number of stitches

If the swatch is small or the yarn is bulky, it can be more accurate to measure how wide a certain number of stitches is and calculate from that:

20 stitches measure 9 cm → 20 ÷ 9 = 2.22 stitches per cm → 22.2 stitches per 10 cm.

The same method applies to rows.

If your gauge doesn’t match

• More stitches per 10 cm than the pattern? You knit more tightly. Change to larger needles, often half a size to a full size up.
• Fewer stitches per 10 cm? You knit more loosely. Change to smaller needles.

Knit a new swatch after changing. It feels time-consuming, but a difference of just 2 stitches per 10 cm adds up across a whole garment.

Why small differences become big

Say a sweater pattern casts on 240 stitches and assumes 24 stitches per 10 cm. That gives a circumference of 240 ÷ 2.4 = 100 cm. If you get 22 stitches per 10 cm, it becomes 240 ÷ 2.2 ≈ 109 cm instead – almost 10 cm too big.

Recalculating a pattern for your gauge

Sometimes you don’t want to change needles, for example because you like how the fabric feels. Then you can recalculate the stitch count instead.

1. Work out how many stitches you have per cm: 22 stitches per 10 cm = 2.2 stitches per cm.
2. Find the measurement the pattern is aiming for (often shown in the schematic), e.g. 100 cm.
3. Multiply: 100 × 2.2 = 220 stitches.

Important for colourwork: The stitch count must be a multiple of the pattern repeat. If the repeat is 8 stitches wide, 220 does not divide evenly (220 ÷ 8 = 27.5). Choose the nearest multiple, 216 or 224, and check what it does to the measurements: 216 ÷ 2.2 ≈ 98 cm and 224 ÷ 2.2 ≈ 102 cm. Choose the one that fits best.

Remember that the rows are affected too. If the pattern gives lengths in centimetres it is easy – knit until the measurement is right. But if it gives a number of rows, or if a motif has to fit within a certain height, you need to recalculate those as well.

Example: how many stitches for a hat?

A typical adult head circumference is around 54–58 cm, but it is best to measure the person who will wear the hat. A hat fits best if it is a little smaller than the head, since knitting stretches. How much smaller depends on the ribbing, the yarn and the fit you want; a few centimetres is a common starting point.

Say the head is 56 cm and you want the hat to measure about 52 cm. Your colourwork swatch gives 26 stitches per 10 cm:

• 52 × 2.6 = 135.2 stitches.
• The pattern, for example a Selbu Star border, has a 12-stitch repeat in this example. 135 does not divide evenly, so choose 132 (11 repeats, approx. 51 cm) or 144 (12 repeats, approx. 55 cm).

Colourwork stretches less than plain stockinette because the floats at the back limit the stretch. So if you are unsure, go for the slightly larger option.

Gauge and the proportions of your pattern

Row gauge also affects how your pattern looks. If you have 24 stitches and 30 rows per 10 cm, each stitch is about 4.2 mm wide and 3.3 mm tall. A chart drawn on square boxes will therefore come out shorter and wider when knitted than on paper.

When you design in KnitGrid’s pattern editor, you see a knitted preview of the chart, with stitches instead of square boxes. That makes it easier to get a reindeer that looks like a reindeer, not a dachshund. Try it with Classic Fair Isle, for example. And read how to go through the whole design process in the guide design your own knitting chart.

Frequently asked questions

How big should a gauge swatch be?

Ideally at least 15 × 15 cm, so that you can measure 10 cm in the middle without counting the uneven edge stitches.

Do you have to wash the swatch?

Yes, if you want to be sure. Yarn can change when it is washed, and colourwork evens out with blocking. Measure when the swatch is dry.

What does “gauge: 22 stitches = 10 cm” mean?

That there should be 22 stitches across 10 cm in the stated technique, usually stockinette stitch, after the swatch has been washed.

Should I change needles if I have too many stitches?

Yes, change to larger needles if you have too many stitches per 10 cm, and to smaller needles if you have too few. Then knit a new swatch.

Do I need to knit a swatch for a hat?

It is wise, especially with colourwork. A hat is a small project, but the wrong gauge shows immediately when it won’t go over your head – or slips down over your eyes. A few rounds of swatching often saves a whole hat.