Hat Size Chart
Typical head circumference for hats, baby to adult, in centimetres and inches.
The measurement a hat has to fit is the way around the head, taken over the widest part just above the ears. This chart collects the head circumferences crafters commonly knit and crochet hats to, from a baby to an adult, in both centimetres and inches. There is no single official hat-size standard, and head size varies from person to person at the same age, so treat these as representative starting points and measure the actual head whenever you can.
Head circumference by hat size
Scroll sideways to see inches →
| Hat size | Head circumference (cm) | Head circumference (in) |
|---|---|---|
| Baby (0–6 months) | 36 | 14 |
| Baby (6–12 months) | 43 | 17 |
| Toddler (1–3 years) | 48 | 19 |
| Child (3–10 years) | 50 | 20 |
| Teen / Adult Small | 54 | 21 |
| Adult Medium | 57 | 22 |
| Adult Large | 59 | 23 |
Circumference is measured around the widest part of the head, just above the ears; inches are rounded to the nearest inch. Once you have a circumference, the Hat Size Calculator turns it into a cast-on from your gauge and a little negative ease.
Good to know
- These are representative head circumferences, not an official standard — heads vary at every age, so put a tape measure around the real head whenever the person is on hand.
- Take the measurement over the widest part of the head, above the ears and eyebrows, with the tape level all the way round. That circle is what the brim has to stretch over to stay on.
- Hats are worked with a little negative ease so the brim grips instead of sliding off. The figures here are the head, not the finished hat — the calculator subtracts the ease for you.
- This chart is circumference only. How deep to knit before the crown depends on the style, from a snug beanie to a slouch, so it is set by the pattern rather than a single standard number.
FAQ
- What is an average adult head circumference?
- Around 57 cm (about 22 in) is a common adult medium, with most adult heads falling between roughly 54 and 59 cm around. Heads vary at the same age and build, so measure rather than relying on the average.
- Is head circumference the same as hat size?
- This chart lists head circumference — the distance around the head — in centimetres and inches. Some retail hats carry lettered S/M/L sizes instead, but those map back to a circumference range, which is the number that actually decides the fit.
- How much smaller than the head should the hat be?
- A little smaller — a few centimetres of negative ease is usual so the brim hugs the head and does not ride up. Ribbing at the brim stretches to help, and the calculator applies the ease once you enter your gauge.
- How do I turn a head circumference into a stitch count?
- Work a gauge swatch, then the Hat Size Calculator combines your gauge, the circumference from this chart and a little negative ease to give the exact number of stitches to cast on.