SkeinMath

Hat size chart for knitting and crochet

Published October 13, 2026.

The best way to size a hat is to measure the head it’s for. When you can’t, for a gift or for charity knitting, use the average head circumference for the wearer’s age.

Head circumference by age

Size Inches Centimeters
Preemie 9–12 23–30.5
Baby 14–16 35.5–40.5
Toddler 16–18 40.5–46
Child 18–20 45.5–51
Tween 20–22 51–56
Adult woman 21–23 53–58.5
Adult man 22–24 56–61

The ranges overlap: a large toddler and a small child can wear the same hat. The source rounds centimeters on its own, which is why, for example, the child range starts at 45.5 cm rather than the 45.7 cm you get by converting 18 inches.

How to measure a head

Place a tape measure across the forehead and take it all the way around the head. Keep the tape snug, not loose.

From head size to stitches

  1. Check the finished hat size your pattern gives for the size you are making.
  2. Measure your gauge on a swatch worked in the round if the hat is worked in the round.
  3. Use the gauge calculator to turn the hat’s circumference into a number of stitches.
  4. For the crown, the increase and decrease evenly calculator spaces the decreases for you.

Questions

What size hat fits an adult woman?

The Craft Yarn Council gives 21 to 23 inches (53 to 58.5 cm) as the head circumference range for women. Measure the person if you can, because heads vary.

What head size is a baby?

The chart gives 14 to 16 inches (35.5 to 40.5 cm) for babies and 9 to 12 inches (23 to 30.5 cm) for preemies.

Should the hat be the same size as the head?

Patterns choose how much smaller or larger than the head their hat is, depending on the stitch and the fit they want. Follow the finished size in your pattern and use this chart to pick which size to make.

Sources

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