Knitting gauge calculator

Gauge is the whole of knitting arithmetic: once you know how many stitches fill a centimetre, every width in the pattern becomes a stitch count and every length becomes a row count. The Craft Yarn Council puts it plainly — you must achieve the gauge specified in a pattern if you want your project to turn out right. This calculator does the multiplication in both directions, and keeps the swatch side you measured over, because four inches and ten centimetres are not the same distance however often they are printed together.

How it is worked out

stitches to cast on = (stitches in swatch ÷ swatch side) × target width

The swatch gives a density — stitches per centimetre or per inch — and the target width multiplies it. Rows work the same way against the height. The result is rounded to a whole stitch, because half a stitch cannot be cast on; over a garment that rounding is worth a fraction of a millimetre.

Source: density × span, the definition of gauge

Questions people ask

Is a 4 inch swatch the same as a 10 cm swatch?

No, and the difference is 1.6%. Four inches is 10.16 cm, so a gauge given over 4 inches spreads the same stitches across slightly more fabric than one given over 10 cm. Patterns routinely print "4 inches (10 cm)" as if the two were identical, which is fine for a scarf and less fine for a sweater: on a 100 cm chest that 1.6% is 1.6 cm, about half a stitch at worsted gauge. Pick the unit your pattern used and this calculator will keep it.

How big should the swatch be?

The Craft Yarn Council says gauge swatches are generally 4 by 4 inches, unless you are working in rounds. Knit it larger than the area you intend to measure and count in the middle — the edges of a swatch curl and pull, and a count that includes them will be wrong in the direction that flatters you.

My gauge does not match the pattern. Now what?

Change the needle, not your knitting. The Council's rule is that if your swatch comes out smaller than the pattern's, try again with a needle one or two sizes bigger; if it comes out bigger, go down, or use a lighter weight yarn. Trying to knit tighter or looser by will does not hold over a whole garment.

Why is the row count usually further off than the stitch count?

Row gauge is more sensitive to tension and to blocking than stitch gauge, and most patterns are written to stitch gauge for that reason — shaping is given in rows but lengths are given in centimetres, so you work to a measurement rather than to a row number. Use the row figure here as a guide to how much yarn and time a piece will take, not as a target to hit exactly.

Does this work for crochet?

Yes. The arithmetic does not care whether the loops came off a needle or a hook — a density and a span multiply the same way. The Council publishes crochet gauge ranges in single crochet over the same 4 inches, so enter your swatch the way you counted it.

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