Hat Size Calculator
Convert head circumference into cm, US, UK and EU hat sizes.
Input Data
System
Size
Results
57
頭圍 ≈ 57 cm；US≈15.9、UK≈15.4、EU≈55.5（近似）。
At a glance:Based on head circumference (cm): US ≈ head/2.54 − 6.5; EU ≈ head − 1.5; UK ≈ US − 0.5 (approximate). Complements ring-size and shoe-size.
Formula
US ≈ head/2.54 − 6.5.
EU ≈ head − 1.5.
How to Use
- Select the input system and value.
- The tool returns head circumference and each size system.
Case Studies
Head 57 cm → US ≈ 15.9, EU ≈ 55.5
57/2.54 − 6.5 ≈ 15.9; 57 − 1.5 = 55.5.
FAQ
Accurate?
Approximate — measure your head for the best fit.
Use case?
Reference when buying hats.
Precision?
1 decimal.
Related Tools
References
Content review: Calculatorism Science Team. Results are for reference only; please refer to the relevant authorities for the official figures.