Crochet hats can be tricky to make and measure, especially since just an inch of crochet fabric can be the difference between a toddler or adult size!

If you’re tired of crocheting hats that are way too big, or way too small, we have a simple math tip to help you with size every time!

Don’t worry. 

We’re not going to show you complicated math equations and numbers. 

This is easy! Anyone can do this!

And, we even created a free calculator tool to help you with the numbers (keep scrolling).

Before you get started, there are some things you may want to know about crocheting hats:

  • How to measure
  • Sizes by age
  • Sizes by style
  • Gauge and size
  • Patterns

CLICK HERE to read more about each of these, and get a handy measurement guide cheat sheet to crochet any size hat!

There are two measurements to understand when crocheting a hat:

  • Circumference: This is the measurement around a circle. For a fitted hat, the circumference of a hat should be the same as the circumference of a head.
  • Diameter: This is the measurement across a circle. When crocheting in center-out increasing rounds, the diameter is the cross section of a circumference.

You can use circumference or diameter to measure the actual stitches you’re creating to crochet perfectly sizes hats!

This is where the math gets exciting…

The number 3.14 (Pi) is going to feel like magic, but really it’s just a helpful math tool!

In the math world, Pi is the ratio of a circle’s circumference to the diameter.

In the crochet world, Pi is going to easily help us calculate the circumference and diameter of our own personal crochet stitch work.

Let’s give it a try!

Start with the circumference: 

If you know what size hat you want to make, divide that number by 3.14.

Example: 22” circumference / 3.14 = 7.006369″

And so, to crochet a hat with a 22” circumference, the diameter of your beginning circle should reach 7”.

Start with the diameter: 

To check what size hat you are making, multiply the diameter by 3.14.

Example: 7” circumference * 3.14 = 21.98”

And so, if your diameter measures 7”, the circumference of the hat you will make will be 21.98”

If you’d like to give this a try yourself using any crochet stitch in joined rounds, here are some simple instructions to try:

CLICK HERE for patterns to crochet single, half double and double crochet stitches in joined rounds!

Ready to make a hat? Click here to try our Ombre Beanie!

Peace + Love + Crochet


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One Comment

  1. Jody Honeyman says:

    I too have been crocheting since I was 5. My mother taught me while doing her own projects. Hardly a day goes by that I don’t pick up and work on a project.

    I enjoy knowing people with like interests. Much more alike than different, we all are connected in many ways. Crochet ROCKS!!

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