Free Cast On Calculator for Any Knitting Project

The number of stitches to cast on depends on two things: the width you want the finished piece to be, and your stitch gauge. Gauge is how many stitches fit in a given length — usually measured per 4 inches from a swatch, not the yarn label.

The formula is straightforward. Take your desired finished width in inches, add ease if the pattern calls for it, then multiply by your stitches-per-inch. Round to the nearest whole number. If your pattern has a repeat, round up or down to the nearest multiple of that repeat.

For a hat, finished circumference minus negative ease gives you the cast on width. For a sweater body, it is the bust or chest measurement plus any positive ease. For a scarf, it is simply the desired width with no ease.

The long tail cast on requires a yarn tail long enough to complete every stitch before you start knitting. A common estimate is about 1 to 1.5 inches of yarn per stitch, depending on yarn thickness. This calculator shows a midpoint estimate. Add extra for very bulky yarns.

If you run out of tail partway through, you can join a second strand and continue, but it creates a join at the cast on edge. Measuring once before you start avoids that. The calculator output gives you enough to work with for most worsted and DK weight projects.

For the cable cast on or knitted cast on, yarn tail length is not a concern. Those methods work from the working yarn rather than a pre-measured tail.