Hat Calculator 🎩
Calculate cast-on stitches for a knitted hat using head circumference and gauge. Get crown decrease rounds instantly.
How to Use the Hat Calculator
Measure the head circumference at the widest point — typically just above the ears and eyebrows. For children, measure carefully as head sizes vary greatly by age.
Enter your gauge in stitches per 10 cm (or per 4 inches). Use the gauge from a blocked swatch in the round for the most accurate result, since flat and round gauges often differ.
The calculator adjusts the cast-on to the nearest multiple of 8 for symmetrical crown decreases. Work k2tog at the end of each of the 8 sections every other round until 8 stitches remain.
FAQ
How do I calculate cast-on stitches for a hat?
Multiply your head circumference by your gauge (stitches per cm), then apply negative ease (typically 10%). Round the result to the nearest multiple of 8 for symmetrical crown decreases.
What is negative ease for a hat?
10% negative ease means the hat circumference is 10% smaller than your head circumference, giving a snug fit. Use 15–20% for a very fitted hat, or 5% for a looser fit.
How do crown decreases work?
Divide your cast-on stitches into 8 equal sections. On every other round, work k2tog at the end of each section (8 decreases per round) until 8 stitches remain, then pull yarn through.
How do I measure head circumference?
Wrap a soft tape measure around the widest part of your head, just above the ears and eyebrows. This is the circumference to enter in the calculator.