Sock Knitting Calculator

Turn your foot measurement and gauge into an exact cast-on number for a snug, well-fitting sock.

Foot circumference (inches)

Gauge (stitches per inch)

Negative ease (%)

How this sock calculator works

A cuff-down or toe-up sock should fit snugly so it stays up and does not bag at the heel. This tool takes your foot circumference and your knitting gauge, applies about 10% negative ease, and multiplies by your stitches per inch. It then rounds the result to the nearest multiple of 4 so the count divides cleanly for the heel, instep, and most stitch-pattern repeats.

Negative ease is the secret to socks that hug. If your foot measures 8.5" around and you knit at 8 stitches per inch, the eased circumference is about 7.65", which lands near 60 stitches. That is why hand-knit socks feel so much better than store-bought ones — the fabric is under gentle tension all the way around.

Heel and gusset guidance

The heel is worked over half the total stitches, and the instep holds the other half. After you turn the heel, you pick up roughly half the heel-flap rows of stitches along each side to form the gusset, then decrease every other round until you are back to your original cast-on count. The gusset card above estimates that per-side pick-up number for you.

How to use it

Measure the ball of your foot with a soft tape, snug but not tight.
Knit a small swatch in your sock yarn and count stitches per inch for your gauge.
Enter both numbers; adjust the ease field if you like a looser or tighter sock.
Read your cast-on, heel, and gusset numbers and start knitting.

FAQ

Why round to a multiple of 4?: It splits evenly between the heel and instep and suits common 2x2 or 4-stitch pattern repeats. Ribbing and cables usually need it too.
How much negative ease should I use?: Around 10% is a reliable default. Use less for chunky socks or wide calves, and up to 15% for very stretchy fabric.
Does this work toe-up?: Yes. The final cast-on count is the same whether you start at the toe or the cuff; only the construction order changes.
My count came out odd for my pattern.: Nudge your ease by a percent or two, or round up to the next repeat. These are starting estimates, not a substitute for a test sock.