Hat Size Calculator
Measure your head circumference and instantly find your US, UK, and international hat size. Free online hat size calculator with conversion charts for men, women, and children.
About This Calculator
Welcome to the Hat Size Calculator — the easiest way to find your perfect hat size from a simple head circumference measurement. Whether you're shopping for a baseball cap, fedora, beanie, cowboy hat, or sun hat, knowing your correct size ensures a comfortable fit every time. This free online tool supports both inches and centimeters, and provides US, UK, and international hat sizes (XS through XXXL) instantly.
How Hat Sizing Works
Hat sizes are determined by measuring the circumference of your head at the widest point — typically about 1-2 cm above your ears and across the most prominent part of your forehead. This measurement is then matched against a standardized sizing chart to determine your hat size. Different regions use different numbering systems: US sizes range from 6 1/2 to 8 1/8, UK sizes from 6 3/8 to 7 7/8, and international sizes from XS to XXXL. The calculator maps your measurement to the closest standard size in all three systems simultaneously.
How to Measure Correctly
For the most accurate results, use a flexible tailor's measuring tape. Wrap it around your head, positioning it about 1-2 cm above your ears and across the middle of your forehead. The tape should be snug against your head but not tight enough to leave an indent. Take the measurement at least twice to ensure consistency. If you don't have a measuring tape, you can use a non-stretchy string and then measure it against a ruler. Remember that hat sizing varies between manufacturers, so when in doubt, the hat size calculator's recommendation to round up to the next size is a safe bet.
Regional Notes
United States: US hat sizes use a numeric scale (6 1/2 to 8 1/8) that is approximately 1/3 the head circumference in inches. Most US hat brands follow this standard. United Kingdom: UK hat sizes are slightly smaller than US sizes — typically 1/8 to 1/4 inch difference. A US size 7 equals a UK size 6 7/8. India and Europe: International sizes (XS-XXXL) or metric measurements in centimeters are commonly used. The calculator displays all three sizing systems so you can confidently order hats from any country.
Frequently Asked Questions
How do I measure my head for a hat?
Use a flexible measuring tape. Place it around your head about 1-2 cm above your ears, at the widest part of your forehead. Ensure the tape is snug but not tight. Record the measurement in inches or centimeters for use with the hat size calculator.
What hat size is 23 inches?
A head circumference of 23 inches (approximately 58.4 cm) corresponds to a US hat size of 7 3/8, a UK size of 7 1/4, and an international size of L. Use the hat size calculator above to find your exact size for any measurement.
What if my head circumference falls between two hat sizes?
If your measurement falls between two hat sizes, it is recommended to choose the larger size. A larger hat can be adjusted for a better fit using hat fillers or sizing tape, while a hat that is too small cannot be comfortably enlarged.
What is the difference between US and UK hat sizes?
US hat sizes are typically about 1/8 to 1/4 inch larger than UK hat sizes for the same head circumference. For example, a US size 7 corresponds to a UK size 6 7/8. The hat size calculator provides both sizes so you can order hats from any region with confidence.
What hat size is large (L) in inches?
An international size large (L) corresponds to a head circumference of approximately 22.8 inches (58 cm). In US sizing, this is 7 1/4, and in UK sizing, it is 7 1/8. This is one of the most common adult hat sizes for men and women.
How do children's hat sizes work?
Children's hat sizes are based on head circumference and age. For infants 0-6 months, head circumference ranges from 15.7 to 16.5 inches (40-42 cm). Toddler sizes go up to about 20.5 inches (52 cm) for ages 4-8 years. Use the calculator for children under 21 inches (53 cm) head circumference.
What is the most common adult hat size?
The most common adult hat size is medium (M), which corresponds to a head circumference of about 22-22.4 inches (56-57 cm). In US sizing, this is size 7 to 7 1/8, and in UK sizing, it is 6 7/8 to 7. This fits approximately 40% of adults.
Can I use the hat size calculator for any hat type?
Yes, the hat size chart works for most hat types including baseball caps, fedoras, beanies, cowboy hats, top hats, and sun hats. However, some hat styles may have specific sizing conventions, so always check the manufacturer's size guide when ordering online.