Knitting & Crochet Math: Gauge, Cast-On Counts, Even Increases, Yarn Amounts & Resizing

What you'll build

What you will be able to do

Each lab ends with a concrete result that you build yourself and the checker confirms, cell by cell.

• Turn five measured swatches into stitches and rows per 10 cm, stitches per inch and the percentage difference to the pattern gauge, so you know which yarn and needle match the pattern.
• Turn a finished width and a gauge into a cast-on count that fits the stitch pattern: raw stitches, rounding to the repeat with MROUND, adding edge stitches and checking the width you will really get.
• Spread a number of increases or decreases evenly across a row: the base segment with INT, the long and short segments with MOD, the new stitch count and a proof that the plan uses every stitch.
• Estimate how much yarn each project needs from the label and a weighed swatch: metres per gram, grams and metres for the whole project, and the number of balls to buy with a buffer, rounded up with ROUNDUP.
• Rewrite a pattern for a thicker yarn: scale stitch counts by the stitch gauge and row counts by the row gauge, round to whole stitches and rows, and check the size difference each rounding causes.
• Plan a top-down raglan yoke: the rounds needed to reach the yoke depth, the number of increase rounds, the final stitch count, and a round-by-round stitch table built with INT or a running total.
• Calculate the stitches in the last round and in the whole piece for flat circles and an oval, then plan a granny-square blanket: squares across and down, squares in total and balls of yarn.
• Turn a year of projects into a log: yarn cost from grams and price per 100 g, project cost with notions, hours and cost per craft with SUMIFS, and a chart of the hours each project took.