Calculadora de Tamanho de Chapéu
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
tamanho = circunferência_cabeça; polegadas = circunferência / π
About this calculator
The Hat Size Calculator converts your head circumference, measured in centimeters, into the corresponding hat size and inches. Simply enter the measurement and the tool automatically calculates the hat number (Brazilian standard) and the approximate diameter in inches. The calculation uses the formula: inches = circumference / π, where π is approximately 3.1416. The hat size is rounded to the nearest whole number.
When to use? Ideal for buying hats online or in physical stores when unsure of the size. Also useful for seamstresses and artisans making custom hats. You just need a flexible tape measure to measure your head at forehead height, just above the ears. The tool eliminates common doubts about equivalence between numbering systems.
Important precautions: Measure the head with the tape snug but not tight. If between two sizes, choose the larger one for more comfort. Hats of different materials (straw, felt, fabric) may fit differently. The calculator provides a standard reference; always check the manufacturer's size chart, as variations exist.
Frequently asked questions
How to measure head circumference correctly?
Use a flexible tape measure. Place it on your forehead, about 2 cm above the eyebrows, passing over the widest part of the head, just above the ears. The tape should be snug but not tight.
What if my measurement is between two hat sizes?
It is recommended to choose the larger size, as a slightly loose hat is more comfortable and can be adjusted with internal padding.
Does the calculator work for children's hats?
Yes, it works for any age. Just enter the child's head circumference. The result will be the standard hat number.
What is the difference between hat number and inches?
The hat number is an empirical scale (e.g., 58, 60), while inches represent the approximate internal diameter of the hat. The calculator provides both.
Do I need to convert centimeters to inches before using?
No, enter the measurement in centimeters. The calculator performs the conversion automatically.