Sock Knitting Stitch Calculator
The cast-on stitch count is the number that makes or breaks a hand-knit sock: too many and it sags, too few and it cuts off circulation. It follows from three things you control: your measured stitch gauge, the foot circumference, and the negative ease that makes the sock cling. This calculator multiplies circumference by gauge, reduces it by your chosen ease, and rounds the result to a multiple that fits your ribbing repeat so the cuff closes evenly. Gauge and ease are yours to enter because they depend on your yarn, needles, and tension.
Sock cast-on formula
Target circumference = foot circ * (1 - ease / 100)
Raw stitches = target circumference * gauge
Cast-on = round(raw stitches / repeat) * repeat
Repeats = cast-on / ribbing repeat
Negative ease shrinks the knitted circumference below the foot so the sock stretches to fit. Rounding to the ribbing repeat keeps the cuff pattern even.
Sock knitting context
- Stitch gauge varies with yarn, needles, and tension; swatch and measure your own.
- Negative ease, often around 10 percent, makes the sock hug the leg and stay up.
- Round the cast-on to your ribbing repeat (4 for 2x2, 2 for 1x1) so the cuff closes evenly.
- Cast-on sets the circumference; heel, gusset, and toe shaping derive from it.
- The inch is defined by the NIST Office of Weights and Measures.
Sock knitting: frequently asked questions
How many stitches do I cast on for socks?
Cast-on stitches equal the target sock circumference times your stitch gauge (stitches per inch). The target circumference is the foot circumference reduced by negative ease so the sock hugs the leg. The calculator multiplies, applies ease, then rounds to a multiple that fits your ribbing pattern.
What is stitch gauge?
Stitch gauge is how many stitches you knit per inch with your yarn and needles, found by knitting a swatch and measuring. It is the single most important input because it varies with yarn weight, needle size, and your tension. Always swatch and enter your measured gauge rather than a generic value.
What is negative ease in socks?
Negative ease means the sock is knit slightly smaller than the foot so it stays up and fits snugly when stretched on. A common amount is around 10 percent, but it depends on yarn stretch and preference, so it is a user input here. Enter the percentage you want the sock reduced by.
Why round to a stitch multiple?
Ribbing such as 2x2 (knit 2, purl 2) repeats over 4 stitches, so the cast-on must be a multiple of that repeat to come out even. The calculator rounds the raw stitch count to the nearest multiple you specify, so your ribbing closes cleanly around the cuff.
Does this size the whole sock?
It sizes the cast-on, which sets the circumference, the most error-prone number in sock knitting. Heel, gusset, and toe shaping then derive from this count in your pattern. Getting the cast-on right from your measured gauge and chosen ease is the foundation everything else builds on.
Official sources
- NIST: Units of length (inch).
- NIST: Office of Weights and Measures.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.