Crochet Hat Sizes: the Flat Circle Method (2024)

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My biggest crochet challenge ever has been figuring out the right crochet hat sizes to make for my loved ones. Because my family lives halfway across the country, I rarely get the opportunity to see them in person. Sometimes, sending a custom sized crochet hat is the only “hug” my family will get from me all year! So, I do my best to make everyone (especially my nephews!) a Christmas hat each year.

If you struggle with how to size crochet hats, this tutorial is for you! I know how important making the right sized hat is, so in this blog post, I’m sharing:

a FREE set of printable crochet hat templates
How to Size Crochet Hats
A Crochet Hat Size Chart by Age
My Crochet Hat Size Formula
How to Measure Crochet Hat Sizes

Free Printable Hat Size Checker

Since I like to take as much guesswork out of sizing crochet hats as possible, I created this crochet hat size chart and size checker tool to share with you all. I know you’ll love using it!

Before we get started, Pin this to Pinterest for Later!

How to Size Crochet Hats

The EASY Way

The most basic process of crocheting a top down beanie or hat has two steps:

Crochet a Flat Circle
Add Height

Yep, it’s really that simple! The trick is knowing the relationship of the circle to the hat size to the head size.

How to Crochet a Flat Circle

The easiest way to crochet a top down hat is the flat circle method. For a top down hat, you’ll start with one round of crochet stitches at the crown of the head.

Typically, it takes 6-10 single crochet stitches, 8-11 half double crochet stitches, and 10-12 double crochet stitches for the first round.

To increase, you’ll be adding stitches to each round. In most cases you’ll add the SAME number of stitches in the first round to each additional round.

For a Single Crochet hat beginning with 8 sc, you’ll increases by 8 stitches each round.

Round 1: 8 sc

Round 2: 16 sc

Round 3: 24 sc

Round 4: 32 sc

etc.

For a Double Crochet hat beginning with 12 sc, you’ll increases by 12 stitches each round.

Round 1: 12 dc

Round 2: 24 dc

Round 3: 36 dc

Round 4: 48 dc

etc.

Keeping Your Flat Circle Flat

Sometimes, you’ll need to adjust to get to the exact right number. Here are three handy rules to help you recognize how to adjust:

If your circle is cupping into a bowl shape, you should add more stitches.
When your circle is ruffling like lettuce leaf’s edge, you should add fewer stitches.
Need to increase just a bit, but not a whole row? You can increase your final round by HALF the stitches in your initial round. (Just make sure to take into account how many stitches your repeat will need!)

How to Add Height

When you’ve reached the right diameter in your flat circle, you’re ready to crochet the sides of the hat! To do so, simply stop increasing, and continue in your stitch pattern.

Crochet Hat Size Chart By Age

The Craft Yarn Council offers a chart of standard hat sizes by age.For the most part, these are fairly reliable. However, I found that I wanted just a little more flexibility in my crochet hat sizes. So, I added a few more sizes, and adjusted the sizes a bit to help me get that elusive perfect fit. Here’s my tried and true crochet hat size chart:

How to measure a head for crochet hat sizes:

If you have the head handy, here’s how to get an exact measurement for a crochet head.

Step one: and in my opinion, the most important step: give them a big ol’ hug. Count yourself lucky to be so close to your loved ones!

Step two: Wrap your tape measure around the widest part of your head. Place it just about where you’d want the hat brim to sit.

Case in point: everyone in my family runs at least an inch larger in hat sizes than the charts say. One of my nephews is already wearing a Teen sized hat!

My Crochet Hat Size Formula

Now that we have some baseline sizing information, let’s talk about the mathematics of crochet hats. Dust off your middle school math, because today we WILL be using that geometry! (Sorry I doubted you, Mrs. C, and thank you for drilling this into my head!)

For the most part, heads are generally round, with a definite, measurable circumference. That means that your hat, which is an open circle at the bottom and a closed circle at the top, will be circular.

How to Measure Crochet Hat Sizes

How Much Can Crochet Hats Stretch?

Now, remember, your crochet hat will stretch a bit. There are a number of different factors that dictate how far a crochet hat can stretch, but that’s well beyond the scope of this lesson.

For the purpose of this exercise, you can assume that the stretch factor is pretty close to 10%, or .1. So, the Head Size will be 1.1 times the Circumference of the hat.

Head Size = 1.1 x Circumference

To solve for the Hat Circumference, divide both sides by 1.1. You’ll end up with:

Head Size / 1.1 = Circumference.

Let’s fill out our chart with the Circumference values we need.

Size:Head Size;Circumference

Okay, so how big should my flat circle be to reach the right circumference?

So, we can figure out exactly how big to make the hat using the geometric relations between circumference and diameter. (Note, you may be more familiar with seeing this expressed in terms of the radius, which is half the diameter.)

Circumference = π x Diameter

Since we have just decided that Circumference is equal to the head size divided by 1.1, we can solve for it this way:

Head Size / 1.1 =π x Diameter

Since we are solving for the Diameter, let’s divide both sides byπ:

Head Size / 1.1 /π = Diameter

Tada! Now we know how big our circle should be before we quit increasing.

So let’s add this new data to our table of crochet hat sizes:

Size:Head Size;Circumference;Diameter

Micro Preemies:9.5″, 24 cm; 8.5″, 22 cm;2.75″, 7 cm

Preemies: 11.5″, 29 cm; 10” 26 cm;3.25″, 8.5 cm

Newborns: 13″, 33 cm;12″, 30 cm; 3.75″ 9.5 cm

0-3 Months:15″, 37 cm; 13.5″, 34 cm; 4.25″, 11 cm

3-6 Months: 16″, 41 cm; 15″, 38 cm; 4.75″, 12 cm

6-12 Months: 17″, 44 cm;16″, 40 cm;5″, 12.5 cm

Toddlers: 18.5″, 48 cm;17″, 43 cm; 5.33″, 13.5 cm

Children:20″, 50 cm;18″, 46 cm; 5.75″, 14.5 cm

Teens: 21.5″, 55 cm;19.5″, 50 cm; 6.25″, 16 cm

Women: 22.5″, 57 cm;20.5″, 52 cm; 6.5″, 16.5 cm

Men:24″, 61 cm; 22″, 56 cm;7″, 18 cm

Am I ready to start crocheting?

You betcha! Next, you’ll want to begin crocheting in the round, and increase evenly until your flat circle has a circumference that will fit the right head size. You’ll want to increase evenly until your hat’s diameter is proportional to the circumference.

Or, just use the handy chart I’ve made for you! See how easy it is for me to check the sizing of my hat?

To increase evenly, you’ll want to add the same number of stitches you started with for each additional row. For example, my Venus Shell Slouch Hat Crochet Patternstarts with 12 double crochets on round one, then increases to 24 on row 2, 36 on row 3, and so on. (Do note that the Venus Shell Slouch Hat’s final size matches the diameter of the second to last round of the flat circle to give extra slouch!)

How Tall Should My Crochet Hat Be?

Finally, you’ll want to make sure your crochet hat has enough length. This does vary some based on the style of hat you’re looking for.

If you want to measure exactly, start by measuring across the crown of your head from ear to ear, like this:

Then, you’ll need to subtract the diameter of your hat, divide by two, and add an inch or two (plus extra for a brim, if you like). That’s how much length should be added past the increases of a beanie.

After analyzing about 15 crochet hat size charts on the web, I noticed there’s a pretty simple formula to find the hat height.

For a basic beanie, your hat height should be equal to your flat circle diameter plus 1.5″.

So let’s add this new data to our table of crochet hat sizes:

Size:Head Size;Circumference;Diameter;Hat Height

Micro Preemies:9.5″, 24 cm; 8.5″, 22 cm;2.75″, 7 cm;4.25″

Preemies: 11.5″, 29 cm; 10” 26 cm;3.25″, 8.5 cm; 4.75″

Newborns: 13″, 33 cm;12″, 30 cm; 3.75″ 9.5 cm; 5.25″

0-3 Months:15″, 37 cm; 13.5″, 34 cm; 4.25″, 11 cm; 5.75″

3-6 Months: 16″, 41 cm; 15″, 38 cm; 4.75″, 12 cm;6.25″

6-12 Months: 17″, 44 cm;16″, 40 cm;5″, 12.5 cm;6.5″

Toddlers: 18.5″, 48 cm;17″, 43 cm; 5.33″, 13.5 cm; 6.75″

Children:20″, 50 cm;18″, 46 cm; 5.75″, 14.5 cm; 7.25″

Teens: 21.5″, 55 cm;19.5″, 50 cm; 6.25″, 16 cm; 7.75″

Women: 22.5″, 57 cm;20.5″, 52 cm; 6.5″, 16.5 cm; 8″

Men:24″, 61 cm; 22″, 56 cm;7″, 18 cm;8.5″

You can adjust that number if you’re looking for a different style of hat. Here are a few examples:

Sun Hats: subtract 1″ before starting the wide brim.
Folded Brim: add 2″ (or the length of your brim) to the length.
Slouch Hats: add 2-3″ (or more!) to the length.

How to Make the Right Crochet Hat Sizes

Let’s recap! To make a perfectly sized crochet hat, you’ll want to:

Determine the size you need.
Crochet a flat circle with a proportional diameter.
Add height to the hat.