Hat Size Calculator
Convert head circumference to US, UK, and EU hat sizes.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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Request a ToolHow to Use the Hat Size Calculator
Finding your hat size takes about 30 seconds with a flexible tape measure:
- Measure your head. Wrap a soft measuring tape around your head about 1 inch above your eyebrows and ears, at the widest point. Keep the tape level and snug but not tight.
- Select your unit. Choose inches or centimeters depending on how you measured.
- Enter the measurement. Type your circumference. The calculator shows your hat size across US, UK, and EU systems.
If your measurement falls between two sizes, round up for a more comfortable fit, especially if you plan to wear the hat for extended periods.
About Hat Sizing
US hat sizes use fractions of inches representing the hat diameter (circumference divided by pi). A size 7 means a 7-inch interior diameter. UK sizes use the same fraction system. EU sizes use the head circumference in centimeters. A US 7 corresponds to an EU 56 and a head circumference of about 21.875 inches or 55.6 cm.
Most baseball caps and fitted hats follow this sizing table. Stretch or one-size caps will list a circumference range instead. Cowboy hats, fedoras, and structured hats are typically the most size-sensitive, while beanies and bucket hats are more forgiving.
Frequently Asked Questions
What is the average hat size for men?
The average hat size for adult men in the US is approximately 7 3/8, corresponding to a head circumference of about 23.25 inches or 59 cm. This is an EU size 59. Men's heads range roughly from 6 5/8 (XS) to 7 5/8 (XL) and above for larger sizes. Most fitted caps are produced in the 7 1/8 to 7 5/8 range as these are the most common adult sizes.
What is the average hat size for women?
The average hat size for adult women is approximately 7 to 7 1/8, corresponding to a head circumference of about 21.875 to 22.25 inches or 55.6 to 56.5 cm. This is an EU size 56-57. Women's fitted hats are typically produced in the same sizing scale as men's, though many women's styles use stretch materials labeled S/M or M/L rather than numeric sizes.
How do I measure my head for a hat without a tape measure?
Wrap a strip of paper or string around your head at the hat line, mark where it meets, then measure that length against a ruler. You can also use a piece of yarn or shoelace, then lay it flat and measure. For a quick estimate, the average person's head fits a medium (EU 57-58), but measuring is always more accurate for fitted hats.
What does EU hat size mean?
EU hat sizes represent the head circumference in centimeters. An EU size 56 hat is designed for a head circumference of 56 cm. This is the most direct measurement system since it uses the actual head measurement without conversion. EU sizes typically range from 52 (very small) to 64 (very large) for adult hats.