How to knit and measure a gauge swatch

Gauge tells you how many stitches and rows fit into 10 cm (4 in). If yours differs from the pattern's, the finished piece comes out bigger or smaller, sometimes by a whole size. A swatch takes an hour and tells you before you've knit a whole sweater.

Why it matters

A sweater with a 100 cm chest, knit at 22 stitches per 10 cm, has 220 stitches around. Knit the same 220 stitches at 20 per 10 cm and the chest measures 110 cm. Two stitches' difference per 10 cm sounds small; on a whole garment it's 10 %.

1. Knit a big enough swatch

• Use the yarn, needles and stitch the pattern asks for (stockinette, or the pattern stitch if the gauge is given in it).
• Make it at least 15 × 15 cm, larger than 10 cm, because the edge stitches are uneven and you measure in the middle.
• Knit it the way you'll knit the piece: in the round if the sweater is in the round, since many people purl looser or tighter than they knit.

2. Wash and dry it

Treat the swatch the way you'll treat the finished piece: wash it, press out the water in a towel and let it dry flat. Many yarns relax or bloom after washing, especially superwash wool, cotton and alpaca. Measuring an unwashed swatch is the most common reason a sweater grows.

3. Measure in the middle

Lay the swatch flat without stretching it. Put a ruler across the middle and count the stitches over 10 cm, halves included. Then count the rows over 10 cm, measured vertically. Measure in two or three places and take the average.

4. If it doesn't match

• More stitches than the pattern (your stitches are too small): use bigger needles.
• Fewer stitches than the pattern (your stitches are too big): use smaller needles.
• As a rough rule, half a millimeter changes the gauge by about one stitch per 10 cm. Knit a new swatch to check.

Stitch gauge matters most. Row gauge matters when the pattern counts rows, for example for raglan shaping or a chart; if it only says “work to 40 cm”, you just knit to the length.

Or recalculate the pattern

If you like the fabric at your own gauge, you can work out the stitches yourself: multiply the width you want by your stitches per centimeter. For a 50 cm wide back at 20 stitches per 10 cm: 50 × 2.0 = 100 stitches, instead of the pattern's 110 at 22 per 10 cm.

Let YarnSpace do the maths

The gauge and cast-on calculator in YarnSpace turns your swatch into stitch and row counts for any width or length, and converts a pattern written for a different gauge. Each project keeps its gauge, so the numbers are there when you need them again.

Gauge, cast-on and more, calculated for you

YarnSpace is the knitting and crochet app for iPhone, iPad, Mac and Apple Watch.

See what YarnSpace can do