Hat Size Chart: How to Find Your Hat Size

How to measure your head with a tape or a string, then match it to US, UK and European hat sizes and to S, M, L and XL. With the simple math behind US hat sizes.

Updated

Side view of a head with a measuring tape wrapped around it just above the ears and eyebrows, labeled 22 3/8 in = 57 cm = US hat size 7 1/8

Your hat size starts with one number: the circumference of your head where a hat sits. European sizes use that number directly, in centimeters, and US sizes are the same measurement divided by π (3.14). The chart below does the conversion for you.

How to measure your head

  1. Use a soft tape measure. No tape? Use a piece of string or a phone charging cable, then lay it straight against a ruler or a printable ruler.
  2. Wrap it around your head about ⅛ inch (3 mm) above your eyebrows and the tops of your ears, and around the fullest part of the back of your head. This is where a hat’s band sits.
  3. Keep it snug but not tight, with one finger’s room. Don’t pull hair up into a ponytail or bun.
  4. Measure twice and use the larger number.

Hat size chart

Head (in) Head (cm) US UK EU Letter size
20½ 52 6½ 6⅜ 52 XS
20⅞ 53 6⅝ 6½ 53 XS
21¼ 54 6¾ 6⅝ 54 S
21⅝ 55 6⅞ 6¾ 55 S
22 56 7 6⅞ 56 S/M
22⅜ 57 7⅛ 7 57 M
22¾ 58 7¼ 7⅛ 58 M
23⅛ 59 7⅜ 7¼ 59 L
23½ 60 7½ 7⅜ 60 L
24 61 7⅝ 7½ 61 XL
24⅜ 62 7¾ 7⅝ 62 XL
24¾ 63 7⅞ 7¾ 63 XXL
25⅛ 64 8 7⅞ 64 XXL

S, M, L sizes differ between brands, especially for stretch-fit caps and beanies, so check the brand’s own chart when you can.

The math behind hat sizes

  • US hat size = head circumference in inches ÷ π. It’s the diameter of a circle with your head’s circumference: 22⅜ ÷ 3.1416 = 7.12, so size 7⅛.
  • European size = head circumference in centimeters, rounded: 57 cm is size 57.
  • UK size is ⅛ smaller than the US size for the same head: a US 7¼ is a UK 7⅛.

To convert your measurement, use inches to cm or cm to inches.

Fit tips

  • Between sizes? Go up. Foam sizing tape behind the sweatband can take up the extra, but a tight hat can’t be fixed.
  • Fitted baseball caps use the US sizes above. Snapback and stretch caps usually cover a range, such as 7 to 7⅝.
  • Straw and felt hats shrink slightly if they get wet; leather sweatbands loosen a little with wear.
  • Long or thick hair can add up to ¼ inch: measure with your hair the way you’ll wear it under the hat.

Frequently asked questions

How do I find my hat size?

Measure around your head, just above your ears and eyebrows, with a soft tape measure or a string. Then find that measurement in the chart. For example, 22⅜ inches (57 cm) is a US size 7⅛, a European size 57 and a medium.

How do you convert head size to hat size?

Divide your head circumference in inches by 3.14 (π) and round to the nearest ⅛. A 22¾ inch head ÷ 3.14 = 7.24, so a US 7¼. European hat sizes are simply the circumference in centimeters.

What is the average hat size?

Most adults wear between 7 and 7⅝. Typical men's sizes center on about 7¼ to 7⅜ (58 to 59 cm), and typical women's sizes on about 7 to 7⅛ (56 to 57 cm).

What if I'm between two hat sizes?

Choose the larger size. A slightly loose hat can be made snug with a strip of foam sizing tape inside the band, but a tight hat gives headaches and can't be stretched much.

More measuring guides