How do I know what hat block form to order?

Can you explain to me a little about the differences in form? How do I know what hat block form to order?

When we refer to ‘form’, we are talking about the shape of the block at the headband of the crown. The form of the headband on the brim should not be confused with the outline. The outline can of course be cut to any shape you wish. Most milliners find that the Slim Oval form provides a good head fitting. Read on to find out a little more about the differences in hat block form.

Often the choice between the forms is really one of aesthetics. Broad Oval crown tips have a pleasant full shape, which is even more pronounced with the Circular form. Slim Oval provides the best head fitting. Even when using Broad Oval crowns, they would normally be fitted to a Slim Oval brim in order to give a comfortable fit. As such, brims are almost always made in the Slim Oval form.




I see Slim Oval, Long Oval, and Broad Oval referred to but I’ve heard terms like Oval 36 and don’t know what this is.

However, there’s more to know with regard to men’s hatting. This is because traditionally men’s hats are often stiffer and use heavier materials. Take the bowler hat for example, a hard felt hat and if the oval isn’t correct, it will be uncomfortable for the wearer. Hatters often use conformateurs to get the exact outline of the wearer’s head and then use a band block (CO3 as pictured below) to get the final shaping to match the customer’s head shape. Some hatters even order blocks in custom ovals for specific customers.

CO3 Band Block








There are Long Ovals and sometimes ovals can be referred to by number, such as Oval 36 or Oval 50. When you see a hat block form named Oval 36 it means that the oval is 36mm longer than it is wide, for example.

This article was written for HATalk and was published in April 2023.

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