Knitting Gauge Calculator
Built by Johnny Alto · free, no sign-up · updated July 26, 2026
Knit a gauge swatch, enter its stitches and rows, then enter the size you want, and the calculator tells you exactly how many stitches to cast on and rows to work. Matching your own gauge, not the pattern's, is what makes a finished piece come out the size you intended.
Cast on0stitches
Work0rows
Always swatch in the same stitch pattern, yarn, and needles you will use for the project, then wash and block it before measuring, since blocking changes gauge. Cast-on is rounded to a whole stitch; adjust to your pattern's stitch repeat if it has one.
Why gauge decides your finished size
Gauge is how many stitches and rows you get per inch with a particular yarn, needle, and stitch pattern. Two knitters can follow the same instructions and get very different sizes because they knit at different tensions. That is why patterns quote a gauge, and why matching it, or recalculating for your own, is the difference between a sweater that fits and one that does not.
The math is simple once you have swatched. Divide your gauge stitches by the width it was measured over to get stitches per inch, then multiply by the width you want. Do the same with rows for the length. This calculator handles gauge measured over four inches, one inch, or ten centimeters, and a target in inches or centimeters.
Swatch honestly
A gauge swatch only helps if it matches the real project. Use the same yarn, needles, and stitch pattern, make it at least four inches square, and wash and block it the way you will treat the finished piece, because blocking can change gauge noticeably. Measure in the middle, away from the edges, and if you are between sizes, change needle size rather than fighting your natural tension.
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Frequently asked questions
How do I calculate cast on stitches from gauge?
Divide your gauge stitches by the width you measured them over to get stitches per inch, then multiply by your target width. At 20 stitches over 4 inches, that is 5 per inch, so a 20 inch width casts on 100 stitches.
Why does gauge matter so much?
Because knitters work at different tensions, the same pattern can come out different sizes. Matching gauge, or recalculating for your own, is what makes a piece finish at the intended size.
Should I block my gauge swatch?
Yes. Wash and block the swatch the way you will treat the finished item before measuring, since blocking can change the gauge noticeably.
What if my gauge is off?
Change needle size rather than trying to knit tighter or looser. Go up a size if you have too many stitches per inch, down a size if you have too few.
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This calculator gives estimates for planning only; always confirm against your own measurements and species research. Some links are to our buying guides, which contain affiliate links. As an Amazon Associate I earn from qualifying purchases.
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