Tips and Tricks Tuesday: Sizing a Crochet Hat

This summer, I crocheted a lot of hats.  It got me thinking about an accurate way to size a hat.  Usually I try things on a lot when I am crocheting, but my head is not always a good reference point.  This summer I was crocheting for babies and men, so I needed a different way to measure the size.  I had to use math.

Technically, a hat is a circle, and the outer boundary of the circle, or circumference, should fit around the person's head.  So the question was:  how can I calculate what the circumference of my finished hat will be?

The answer is to use the formula for calculating circumference: diameter(π). 

 Knowing that π = 3.14, we can use this formula to figure out what diameter is needed to get the necessary circumference.  First, I needed to measure the head.  I cut a string and measured where I wanted the brim of the hat to sit on the person's head.  When I measured that string, I knew what the circumference of the completed hat needed to be.  I then plugged it into the formula.

Circumference = 39.5 cm

39.5cm = diameter(3.14)

12.5796cm = diameter

Remembering that most yarns will stretch a little, I crocheted my initial circle to a little less than the actual measurement and then continued with my hat.  I used this same method to size some baby hats after mommy sent me some head measurements.  This simple math trick can help you easily size crochet hats for anyone.

Have you ever used this trick to help size a crochet hat?