The Ultimate Hat Size Guide for Crocheters & Knitters 
Making a hat that fits may not seem like a difficult task at first, but there’s more to it than just circumference. For a hat to be snug and to effectively keep your head and ears warm, it needs to stretch a little. But how much? And how long does it need to be? These are the questions we aim to answer in this guide.
This guide was designed to answer all your questions about sizing a hat and knitting or crocheting a hat that fits. We’ll look at things like how to measure a hat, negative ease (and what that means for hat sizes), and then we’ll get to the finer details, to take what you’ve learned and apply it to a real life project. We’ll help you answer commonly asked questions like “is there a standard hat size chart?”, “How do you measure your hat size” and “what size hat for a baby? Man? Teen?” Basically, we’ll help you understand how there’s more to sizing a hat than just the circumference. And finally, we’ll give you a step-by-step framework to crochet or knit a hat that fits your recipient perfectly.
One thing we’ll mention…the contents toward the end of this guide will be the most useful if you are NOT following a pattern, but rather making one up on your own. Anytime you follow a pattern from a book, magazine, online or here on this website, you can trust that the fit will be right (as long as your gauge matches the pattern), and there’s no additional steps you need to take. Just choose the size you need from the pattern notes and follow the instructions for that size.
That being said if you do not have a pattern and you want to work something up on your own, you’ll need to follow everything in this guide to ensure a proper fit. It’s not for everybody, but it can be a lot of fun if you like this sort of thing.
- How to Measure for a Hat that Fits
- How to Take Hat Size Measurements
- How to Size a Hat If You Can’t Take Measurements
- Negative Ease
- How to Collect Measurements for a Custom Fit Hat
- How to Calculate Crown Diameter for Top-Down Hats
- Hat Sections
- What About Slouchy Hats?
How to Measure for a Hat that Fits
Whether you’re following a pattern or setting out to create your own, knowing what size to make starts with taking (or having) accurate measurements. Fortunately, sizing a hat is much more straightforward than a sweater for example. To make a hat that fits, you only need two basic measurements:
- Head circumference
If making a hat for yourself or a close relative, you have the benefit of taking measurements directly. As you’d imagine, this will lead to the best fit every time. But this isn’t always possible. If you’re making a gift, stocking for a fall market or making a pattern to share online, you need accurate measurements for all age groups.
How to Take Hat Size Measurements
Get a tape measure and start with the circumference. Wrap the tape measure around the middle of the forehead, making sure it’s straight all the way around. You want it snug (but not too snug), and not sagging. Record the measurement you see with as much detail as possible. Avoid rounding too much, but generally speaking, keeping it to one decimal place should be accurate enough.
To measure the length of the hat, position the tape measure at the middle of the crown and run it down the side to the bottom of the earlobe. Then record that number as the hat length.
With these measurements, you can go back to your pattern and choose the best available size.
Nearly all professionally written crochet and knitting hat patterns with have size groups rather than individual sizes and it’s perfectly safe to assume they’ll fit if you choose the right age group based on your measurements. Some of the age groups may seem a little vague though. Generally speaking, these are the specific ages that fit into these groups.
|Hat Circumference Range |
To take your own measurements, you’ll need a tape measure. Starting with the circumference, wrap the tape measure around the middle of the forehead, making sure it’s straight all the way around. You want it snug (but not too snug) and not sagging. Record the measurement you see with as much detail as possible. Try to avoid rounding too much…but generally speaking, keeping it to one decimal place should be accurate enough.
To measure the length of the hat, position the tape measure at the middle of the crown and run it down the side to measure just to the bottom of the earlobe. Record that number as the hat length.
With these measurements, you can go back to your pattern and choose the best available size. Nearly all professionally written crochet and knitting hat patterns with have size groups rather than individual sizes and it’s perfectly safe to assume they’ll fit if you choose the right age group based on your measurements.
How to Size a Hat If You Can’t Take Measurements
If you’re not able to take custom measurements, don’t worry. You can just as easily use standard measurements. This approach may mean it’s no longer a custom fit, but it should still fit reliably nonetheless. Although you can find hat size charts all over the internet, the most reliable measurements will come from The Craft Yarn Council’s website.
The Craft Yarn Council is an organization that represents the leading yarn companies in the yarn industry including Bernat, Caron, Lily Yarns, Lion Brand, Love Crafts, Patons, and Red Heart. They have systems in place to bring uniformity to the yarn industry making it easier to prepare consumer-friendly patterns while ensuring all yarns produced by these companies will include certain standards on their labels like weight and yardage. In addition to this, they’re trusted as the most reliable source for standard body measurements including hat sizes.
We recommend you take a look at their head circumference chart and find the age category for the hat you wish to make. Right away you’ll notice there isn’t a single measurement but rather, a range. For example, the head circumference for a toddler is listed as 16-18″. This range is intended to include children between the ages of 1 and 3. Since their head sizes will vary based on the individual, and their specific age, a range is a safer bet to make a “one size fits all toddlers” kind of approach.
Since you can only have one head circumference, now the question becomes, “what size in the range should I pick?”
When we design a hat pattern for B.Hooked, we use the average of the range, and that has worked really well for us. Although this might seem like it’ll lead to a hat that may or may not fit, there’s one more thing to consider.
Fortunately, the circumference you measure (or the circumference you “pick” in the given range”) isn’t the actual circumference of the hat. If you were to crochet or knit a hat that’s the exact circumference you measure or the exact size of the recipient’s head, the hat wouldn’t fit properly.
That leads us to our next topic.
Any traditional “beanie” you buy in a store will stretch when you put it on. That is negative ease at work. If the hat didn’t stretch when you put it on it wouldn’t be very warm, and it may not even stay on. Negative ease is needed to cause the stretching which leads to the best fit.
Negative ease is essentially a measurement subtracted from the measured circumference.
How much you ask? Fortunately, it’s pretty straightforward. A standard and widely accepted negative ease for crochet and knitting hats is 2.55″, which means you should subtract 2.55 inches from your head circumference. Why? Because most stitch patterns and yarn combos will allow the project to stretch at least this much.
To make things easier for you, here’s the exact hat size chart we use in the patterns here at B.Hooked. This chart was derived from the Craft Yarn Council head circumferences chart we talked about earlier. We just went ahead and did the math so you have a list of “circumference range averages” like we talked about.
|Band Circumference |
minus Negative Ease
How to Collect Measurements for a Custom Fit Hat
Like we mentioned earlier, you need two measurements to crochet or knit a hat that fits: circumference and length, and since you’re “freehanding” a hat without a pattern, grab a calculator and do the following:
- Measure and record head circumference with a tape measure or pull directly from the hat size chart above.
- Subtract 2.55 from the circumference. This value becomes your “target hat circumference” and will be the true circumference of the finished hat.
One thing you won’t find in the Craft Yarn Councils head circumference chart is a list of recommended hat lengths. However, we’ve determined an accurate length for a variety of sizes.
|Total Hat Length|
Along with your target hat circumference, you’ll want to record the length as well. This is how long your hat will measure from top to bottom when lying flat. With these two crucial pieces of the puzzle figured out, the next step will be to design a hat that’s exactly that size. Not a simple task, but not an impossible one either.
How to Calculate Crown Diameter for Top-Down Hats
When you work a hat starting at the top, you’ll need to increase to a certain poin called the crown diameter, then increases are no longer needed to work the sides and band of the hat. Since the crown circumference generally sets the widest point of the hat, this calculation can be the difference between a hat that fits and one that doesn’t.
To calculate crown diameter, take your target hat circumference (the one with negative ease, not your actual circumference measurement) and divide it by 3.14. This calculation is as wide as your crown can be. In other words, crown diameter is the measurement you work towards before you stop increasing.
To this point we’ve talked a great deal about the circumference and target circumference but we haven’t explored the hat length details nearly as much. After all, a hat that’s the right length is just as important as one that stays put and keeps your ears warm. So how do you properly design at hat that’s the right length too?
It’s not as easy as stopping when it’s the right length. Sure you can wing it, and it may even turn out, but it’s always best to do a little planning first.
Breaking a hat into sections will help you plan for a hat that’s the right length. Flat and sewn hats are the exception of this but if you’re making a top-down or bottom-up hat, you can break the pattern into three main sections:
- hat sides
The hat length you measured or pulled from our chart is the total length of all three sections. The crown and band will usually be a fixed length and the hat sides will vary based on the overall size of the hat. The crown is a little more complex so let’s address that first.
With top-down hats, the crown is made up of increases. Alternatively with bottom-up hats, the crown is made up of decreases. But either way, the total height of the crown can be calculated without too much fuss. At this point you already know your crown diameter and target hat circumference, and with a little high school (middle school?) math, you can easily figure out the crown height.
To calculate the crown height, divide your target hat circumference by 6.28
So with that you have one of the three pieces you need. Now let’s talk about the band height. We mentioned before that band height is usually a fixed length. Of course that’s completely up to you and what you want for the design but here’s our standard band height based on size groups.
Now you should have a height for the band and crown which just leaves one…the sides. You also know the total length you want the hat to be so in order to figure out how long to make the sides of a hat, subtract the crown height and band height from the total length. What you have left will be the length of the sides.
What about slouchy hats?
Slouchy style hats, or hats that hang off the back of the head have grown in popularity over the years. Fortunately, you only have to change one thing from all of this to make a slouchy hat instead of a “normal fitting” hat – the length. Depending on how much you want the hat to sag off the back, you’ll want to add more length to the sides of the hat.
As a general rule of thumb, add 2 inches to the sides of the hat to make it slouchy.
If you’re feeling a little overwhelmed at this point, don’t worry. It’s honestly not easy for these things to sink in on the first try. To help ease the self doubt, the best thing you can do is practice. Make a hat based purely on measurements using the steps in this guide and see how it goes. If it doesn’t work out the first time, assess why, adjust and try again.
There are few things more rewarding than taking an idea from your head and putting it into physical stitches. Although this guide wasn’t meant to be a “how to design a hat” guide, we think this gives you more creative freedom to design what you want and learn with every project.