Tips
Why Your Gauge Swatch Lies (and How to Make It Honest)
The advice to make a gauge swatch is universal and slightly incomplete. A swatch that lies will send you into a sweater with the wrong numbers and a firm belief that they are right.
Here are the five ways swatches mislead, and what each one costs.
1. It is too small
Edge stitches behave differently from the middle of a fabric: they pull in, spread out and generally lie. If your swatch is exactly 10 cm wide, every stitch you measure is an edge stitch.
Work at least 15 cm square and measure the middle 10 cm, well away from all four edges. It costs more yarn and twenty extra minutes, and it is the difference between a real measurement and a guess.
2. It was not blocked
Blocking changes gauge, and for some fibres it changes it enormously. Superwash wool can grow substantially when wet; cotton relaxes and lengthens; linen softens and spreads.
Since your finished garment will be washed, the honest measurement is the blocked one. Wash and dry the swatch exactly the way you intend to treat the finished object — including the tumble dryer, if that is what will really happen.
3. It was worked flat for a project in the round
Most people have different tension knitting than purling, so stockinette worked flat (alternating knit and purl rows) does not match stockinette worked in the round (all knit).
If the project is a sock, a sleeve or a yoke worked in the round, swatch in the round too. A small tube, or the speed-swatch trick of working right-side rows only and cutting the yarn each time, both work.
4. Row gauge was ignored
Stitch gauge gets all the attention because it determines width, and width is what people fear getting wrong. Row gauge determines length, and it matters wherever a pattern counts rows rather than measuring: raglan shaping, armhole depth, sleeve increases spaced every fourth row.
If your row gauge is off, shaping that the pattern spreads over 40 rows lands in the wrong place on your body even though the width is perfect. Measure both, and if only one can match, match the one your pattern relies on.
5. The needles changed
Slick metal needles produce looser tension than grippy wood for most people, at the same nominal size. Swatch with the needles you will actually use, including a different brand of the same size.
The same applies to your own mood: tension measured while relaxed on the sofa is not tension produced while tense on a train. If your swatch was worked in one sitting and the garment over three months, expect some drift and re-measure the piece as you go.
What to write down
A swatch is only useful if the numbers survive. Note the needle or hook size, the yarn and colourway, stitch gauge, row gauge, and whether the measurement was taken blocked or unblocked.
Keep it with the project rather than in your head. Six weeks later, "I think I used the 4mm" is not a measurement, and re-swatching costs another evening.
Frequently asked questions
How big should a gauge swatch be?
At least 15 cm square, so you can measure the middle 10 cm away from the edges. Edge stitches distort, so measuring a 10 cm swatch measures nothing but distortion.
Should I block my gauge swatch?
Yes. Blocking can change gauge substantially, especially with superwash wool, cotton and linen. Wash and dry the swatch the way you will treat the finished piece, then measure.
Does row gauge matter?
It matters whenever a pattern counts rows instead of measuring — raglan shaping, armhole depth, evenly spaced increases. Get it wrong and the shaping lands in the wrong place even if the width is correct.
What if I cannot match both stitch and row gauge?
Match the one the pattern depends on, which is usually stitch gauge for width. Then convert the row instructions to measurements using your own row gauge, and keep a counter so you know how many rows you have actually worked.