Cast-On Count Calculator
A general-purpose cast-on calculator for any circular project, with sensible ease defaults by garment type.
Cast-on count
One formula, different defaults
Every circular cast-on starts the same way: a finished circumference, adjusted by an ease percentage, converted to stitches with your gauge. What changes from project to project is the ease — how much smaller or larger the fabric should be than the body part or space it's meant to fit.
Pick a project type to load a conventional starting ease, then adjust it to taste, add any selvage stitches your construction needs, and round to whatever stitch-pattern repeat you're working.
Frequently Asked Questions
How is this different from the sock size calculator?
The sock calculator is tuned specifically to standard sock construction and its usual 10-15% negative ease. This tool is general-purpose: it covers any circular project, with a different default ease for a hat, a mitten cuff, a cowl, or a sweater body — and lets you override that default freely, since the right ease genuinely varies by project and yarn.
Why is a hat's ease negative and a sweater's positive?
A hat needs to grip the head to stay on, so it's typically knit a bit smaller than the head's measured circumference — negative ease. A sweater is usually meant to move with the body and layer over other clothing, so it's commonly knit a bit larger than the body's measurement — positive ease. Both are conventions, not rules; a fitted sweater might use zero or even negative ease.
What are selvage or seam stitches?
If a project is worked flat and seamed rather than in the round, patterns sometimes add one or two extra stitches at each edge for a clean seam allowance — these aren't part of the working stitch pattern and get added after the main stitch count is calculated. Leave this at zero for anything worked seamlessly in the round.
Ease defaults are conventional starting points, not fixed rules. Swatch and adjust to your own preference.