How to Measure my Hat Size?

Hat sizes can be confusing. This page will help you understand how to accurately measure your head, how to recognize metric sizes from imperial sizes, and how to determine what hat size you need, depending on the hat or cap’s shape, construction, and manu

How to Measure My Hat Size?

The most practical way to measure your head size is to use a soft measuring tape to measure the circumference of your head. We recommend you measure just slightly above the eyebrow ridge, passing about one finger’s width over the ears, and over the crest of your occipital, at the back of your head. 

The sensation of the tape on your head will mirror the sensation of the sweatband of your hat. Be mindful of not wrapping the tape too tightly around your head, as it might result in a hat that might be too snug for you.

Once you have found the comfortable measure, use our Hat Size Conversion chart below to get a sense of your hat size. Remember that each manufacturer builds their hats differently, and fits vary with a hat or cap’s rigidity features. If you want to enquire about a specific hat or cap’s fit, find it on our online store with fast shipping, or ask your questions directly to our team of hatters!

Hat Size Conversion









54 cm

6 ¾”

21 ½”


55 cm

6 ⅞”

21 ⅝”


56 cm


22 ¼”


57 cm

7 ⅛”

22 ½”


58 cm

7 ¼”



59 cm

7 ⅜”

23 ⅜”


60 cm

7 ½”

23 ¾”


61 cm

7 ⅝”



62 cm

7 ¾”

24 ½”


63 cm

7 ⅞”



64 cm


25 ¼”

Common Hat Size Units

Manufacturers from different parts of the world use different measuring systems to design their hats. Here is an overlook of the main hat sizing systems you may encounter:

  • Metric

The metric system is used all-over the world. Sizes in the metric system measure the circumference of the hat’s sweatband, and are usually between 55 cm and 62 cm. 

  • Imperial / USCS

These systems use the inch as their base unit of measurement. They are common in the Commonwealth nations and the United States of America. Sizes in the imperial / uscs systems measure the diameter of the hat’s sweatband, from front (forehead) to back (occipital). They are generally between 6 ⅞” and 7 ¾”.

  • Letter System

This system is commonly encountered. It represents the hat’s size using the words Small, Medium, Large, Extra Large, etc. There is usually less size variety in the letter system, whereas the metric and imperial/uscs systems offer more precise sizing.

Hot to Shrink or Stretch my Hat or Cap?

Depending on how your hat is built, we might just be able to fine tune your hat’s fit with an adjustment. We can stretch soft hats using custom built vintage hat stretchers, or sometimes shrink hats using cotton or cork to thicken the hat’s sweatband. Come to the Henri Henri hat store today to get your hat shrunk or stretched!