Crochet Hat Size Calculator
Turn head circumference and gauge into an estimated finished hat circumference, stitch count, crown diameter and hat height.
Add your head measurement and gauge.
How crochet hat sizing works
Most fitted crochet hats are made slightly smaller than the wearer’s head so the fabric stretches comfortably. This is called negative ease. The amount depends on stitch pattern, fiber and desired fit, so use the result as a starting point and compare it with your pattern.
Crown diameter
For top-down hats, crown diameter is often estimated from the target circumference divided by π. Stop increasing when the crown is near that diameter, then work even until you reach the desired height.