How to Calculate Hat Size
What is Hat Size?
Hat size is based on head circumference. US/UK sizes represent approximate head diameter in fractions of an inch; EU sizes equal head circumference in centimetres.
Formula
Step-by-Step Guide
- 1Measure head circumference just above the ears
- 2US/UK size ≈ circumference (inches) / π
- 3EU size = circumference in cm
- 4Hat should sit levelly 1–2 cm above the ears
Worked Examples
Frequently Asked Questions
What is Hat Size?
Hat size is based on head circumference. US/UK sizes represent approximate head diameter in fractions of an inch; EU sizes equal head circumference in centimetres
How accurate is the Hat Size calculator?
The calculator uses the standard published formula for hat size. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.
What units does the Hat Size calculator use?
This calculator works with centimetres, inches. You can enter values in the units shown — the calculator handles all conversions internally.
What formula does the Hat Size calculator use?
The core formula is: EU size = circumference in cm. Each step in the calculation is shown so you can verify the result manually.
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