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Hat size conversion chart

Every hat sizing system comes from one measurement: your head circumference. Enter it once to convert to any system, or read the chart below.

Hat size calculator

Your hat size
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Your head circumference
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Enter your head measurement to see your size in every system.

Hat size conversion chart

The chart lines up every system for head sizes from 46 to 66 cm. US and UK sizes are fitted sizes in eighths of an inch, EU and French sizes are centimetres, and letter sizes follow the most common brand ranges.

Hat size conversion chart
cmInchesUSUKLetter
46 18 ⅛ 5 ¾ 5 ⅝ –
47 18 ½ 5 ⅞ 5 ¾ –
48 18 ⅞ 6 5 ⅞ –
49 19 ¼ 6 ⅛ 6 –
50 19 ⅝ 6 ¼ 6 ⅛ –
51 20 ⅛ 6 ⅜ 6 ¼ –
52 20 ½ 6 ½ 6 ⅜ XS
53 20 ⅞ 6 ⅝ 6 ½ XS
54 21 ¼ 6 ¾ 6 ⅝ S
55 21 ⅝ 6 ⅞ 6 ¾ S
56 22 7 6 ⅞ M
57 22 ½ 7 ⅛ 7 M
58 22 ⅞ 7 ¼ 7 ⅛ L
59 23 ¼ 7 ⅜ 7 ¼ L
60 23 ⅝ 7 ½ 7 ⅜ XL
61 24 7 ⅝ 7 ½ XL
62 24 ⅜ 7 ¾ 7 ⅝ XXL
63 24 ¾ 7 ⅞ 7 ¾ XXL
64 25 ¼ 8 7 ⅞ 3XL
65 25 ⅝ 8 ⅛ 8 3XL
66 26 8 ¼ 8 ⅛ 3XL

How to convert between systems

  • US to UK: subtract ⅛. A US 7 ⅜ is a UK 7 ¼.
  • UK to US: add ⅛. A UK 7 is a US 7 ⅛.
  • US to cm: multiply by 3.1416 to get inches, then by 2.54. A 7 ⅜ is 58.8 cm.
  • cm to US: divide by 2.54, then by 3.1416, and round to the nearest eighth.
  • European, French, Italian, Japanese and Korean sizes all use the head circumference in centimetres.

US hat sizes with cm and inches

US hat sizes with cm and inches
USLetterInchescmUKEU/FR
6 ¼ – 19 ⅝ 50 6 ⅛ 50
6 ⅜ – 20 ⅛ 51 6 ¼ 51
6 ½ XS 20 ½ 52 6 ⅜ 52
6 ⅝ XS 20 ⅞ 53 6 ½ 53
6 ¾ S 21 ¼ 54 6 ⅝ 54
6 ⅞ S 21 ⅝ 55 6 ¾ 55
7 M 22 56 6 ⅞ 56
7 ⅛ M 22 ½ 57 7 57
7 ¼ L 22 ⅞ 58 7 ⅛ 58
7 ⅜ L 23 ¼ 59 7 ¼ 59
7 ½ XL 23 ⅝ 60 7 ⅜ 60
7 ⅝ XL 24 61 7 ½ 61
7 ¾ XXL 24 ⅜ 62 7 ⅝ 62
7 ⅞ XXL 24 ¾ 63 7 ¾ 63
8 3XL 25 ¼ 64 7 ⅞ 64
8 ⅛ 3XL 25 ⅝ 65 8 65
8 ¼ 3XL 26 66 8 ⅛ 66

Fit tips

  • Letter sizes are the least reliable conversion. Always check the brand’s own range.
  • When a conversion lands between two sizes, round up for structured hats.

How to measure your head

  1. 1 Use a soft tape measure, or a string and a ruler.
  2. 2 Wrap it around your head where the hat will sit: about 1 cm (⅜ in) above your ears and across the middle of your forehead.
  3. 3 Keep the tape level and snug, not tight. Do not pull it in.
  4. 4 Read the number where the tape overlaps. Measure two or three times and use the largest value.
  5. 5 Type the number into the calculator, or find it in the chart.
How to measure

Frequently asked questions

How do you convert a US hat size to UK?

Subtract one eighth. US 7 ¼ is UK 7 ⅛, and US 7 ½ is UK 7 ⅜.

What is a European hat size?

It is your head circumference in centimetres. A 58 cm head is a European size 58.

What is size 7 ¼ in cm?

7 ¼ is 57.9 cm (7.25 × 3.1416 × 2.54).

Do women’s and men’s hat sizes convert the same way?

Yes. Hat sizes are unisex. The same head measurement gives the same size; only the stocked range differs.

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