Hat Knitting Tips And Hat Size Chart

Hat knitting is such a fun and rewarding knitting project.  They're small enough to stuff in your knitting bag and take with you. 

And they're a nice quick to knit project if you're looking for gift knitting ideas or an almost instant gratification project.

They're also a great stash buster.  Most knit hats take less than one skein of yarn.  So pull out some of those half balls of yarn and knit a hat.

As you learn how to knit hats you may decide that you'd like to design your own.  Or you may want to use the yarn you already have on hand. 

Hat Knitting

So I though it might be helpful to create a downloadable hat size chart for a quick reference to help you. 

Plus I have some hat knitting tips to help you along the way also.  I love to knit hats and thought you might too once you understand a few hat knitting basics. 

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I'll help you figure out how to measure your head for the perfectly fitted hat and also give you some pointers for decreasing at the crown.

Before I get started, there's one big question I hear so often and that is:  Can I knit a hat with straight knitting needles?

Absolutely yes!  You can knit hats flat.  In fact it's still my favorite way to knit them.  

I can knit hats either way but my first choice will always be to knit them flat just because I enjoy knitting them that way.  :)

The only difference is you'll need to seam the hat up the back.  And honestly it's very simple to do.

How To Measure Your Head Circumference

To measure your head for hat knitting you'll need to measure around your forehead and just above the ears.  

Hat knitting - measuring hat size

Go around the widest part of your head and keep the tape comfortably snug. 

Important Hat Knitting Tip

You're finished hat should be 2 - 4 inches smaller (negative ease) than you're actual head circumference.  I usually knit mine 2 inches smaller. 

The reason for this is because you want your hat to fit comfortably snug on your head.  

If you knit a hat the same size as your head size it will end up slipping down and being too loose and it just won't fit comfortably.

Also, keep in mind that if you use a very stretchy yarn or stitch pattern like ribbing you'll need to take that into account. 

What that means is you may need to leave even more negative ease so that your hat won't be too loose.

How Long Should A Knitted Hat Be Before Decreasing? 

How to Measure Your Head For Hat Length

The hat length is also an important measurement so that you knit your hat to the proper length. 

hat knitting

To measure the length take your tape measure and put it at the base of your ear and go up over your head and down to your other ear at the base. 

Find that measurement and divide by 2.  That's the length you'll need.

Most average adult hat lengths will be around 16 inches and large adult hat lengths will be around 18 inches.  So 18 divided by 2 is 9 inches. 

So basically when you knit a hat, you'll knit anywhere between 8 and 11 inches in length. When you knit it longer it's usually because you want to roll up the brim (to win haha) or maybe your knitting a slouchy hat.

Now that you have your measurements you're ready to get started with your hat knitting. 

So How Many Stitches Do You Cast On To Knit A Hat?

That depends on what kind of yarn you have.  If you're using say a sock yarn you'll need a lot more stitches than if you're using a worsted weight or bulky yarn. 

Here's what I do.  My head is 22 inches so I always plan to knit my hats at 20 inches, 21 if I'm using a tighter stitch pattern or one with cables where there isn't going to be a lot of stretch.

Next thing is to check the yarn label for suggested needle size and gauge.  The link is there for you to check what to look for if you need a reminder.

And it's always a good idea to make a gauge swatch to find out how many stitches per inch I get with the yarn.  So if I'm getting 4 stitches per inch I multiply 4 X 20 = 80 sts.

If I'm getting 3 stitches per inch I'll multiply 3 X 20 = 60 stitches to cast on and so on.

If you're using a stitch pattern adjust the amount of stitches so that it comes close to the number you need to cast on. 

If you have to go up or down a couple of stitches it's totally fine.

How to Decrease Knitting at Crown of Hat

There are many ways to figure out how to work the hat knitting decreases at the crown of a hat.  Some are very intricate for special design knit hats.

The way I show you will be for a simple basic knit hat. And keep in mind that you can work this with your numbers too.  Once you do it a few times it'll get easier.

I think the most important thing to keep in mind with crown decreases are to have the decreases evenly spaced around the top.  

The most common decrease method for working the top of the hat is by dividing the stitches into eight groups of stitches.

So if I have 80 stitches on my needle.  Figure out some numbers that can be divided by 80.

Here's a few;  2, 4, 5, 8, 10, 16, 20.  You can basically choose any of these numbers but I'm going to choose 10. It's the easiest I think.

It might be helpful for you to use stitch markers so you can mark off each section.

So by choosing 10 I'm going to create 8 groups of stitches on the top of the hat with 10 stitches in each section. 

And I'm going to need to make a decrease in each group of stitches with the K2tog (knit 2 stitches together) decrease.

The k2tog involves 2 stitches so you'll work out the formula like this:

10 sts - 2 sts for the k2tog = 8 so you're first row will look like this:

*Knit 8, k2tog, repeat from * around or across the row.

Usually there is a knit or purl row after the decrease row.

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Then the rest of the decreases are easy.  You'll use one stitch less on following rows.  So the next decrease row will look like this:

*Knit 7, k2tog, repeat from * to end of row.

When you've decreased to about 40 stitches, give or take, stop knitting the plain row in between the decrease rows. 

Now you can decrease on every row until you finish with K2tog right around.

Quicker Decreases For The Hat Crown

Depending on the hat style you're knitting you may want to decrease faster so you may want to choose a smaller number like 4 or 5. Let's say 4.

4 goes into 80, 20 times and the formula will be,  4 - 2 (for the k2tog) = 2.  

And you'll decrease 20 stitches in the first decrease row, here's how it'll work:

*Knit 2, k2tog, repeat from * to end of row 

Put in a plain knit row because there's such a sudden drop in stitches.

Then move down to:

*Knit 1, k2tog, then 

Maybe another plain row depending on your preference and then...

K2tog and you're done.

I used this quicker way to decrease for my knit hat pattern and it worked out nicely.  

It's all basic math and pretty easy to figure out most times.  So what happens if you're working with a stitch pattern?  

You're going to have to plan out your decreases more carefully if you want to stay in pattern.  Unfortunately there is no magic formula for that.

What you need to do is find places in the stitch pattern where you'll be able to make the decreases.

Then keep in mind that you've made the decreases and work the stitch pattern accordingly.  It can be done, you'll just need to think about it a little.

You can download the hat size chart here

Hat Size Chart For Hat Knitting 


Preemie - 1 to 2 lbs

Preemie - up to 4 lbs

Preemie - up to 6 lbs


Baby up to 6 months

Baby up to 12 months

Toddler up to 3 years

Child up to 10 years


Adult Woman

Adult Man

Head Circumference

9 inches


12 - 13





19 - 20

21 - 21.5

21.5 – 22.5

22.5 – 24

Hat Length



4.5 - 5









The hat lengths include extra length for turning up the brim of your hat.  It's usually between 1 and 2 inches. 

Hope this helps.  Happy Hat Knitting!

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