Knitting and Crochet Gauge Calculator
Turn your swatch into stitches and rows per inch, the stitches to cast on for a width, and a pattern resized to your gauge.
How this is calculated
Gauge is stitches (and rows) per inch: the count across the swatch divided by the inches it was measured over. Count over the middle of a washed and blocked swatch, away from the edges, and include half stitches.
The stitches for a width are the width times the stitches per inch, and the rows for a length are the length times the rows per inch, rounded to whole stitches and rows. Patterns that need a multiple of stitches (for ribbing or a stitch repeat) need the count adjusted to the nearest multiple.
To use a pattern at a different gauge, multiply each stitch count by your gauge divided by the pattern's gauge. The piece then comes out the size the pattern intended.
Limits
Flat, even fabric. Shaping, lace and textured stitches can change gauge from one part of a piece to another. Resizing stitch counts does not resize a stitch pattern's repeat; check it still fits.