In this tutorial we will discuss how to measure and custom-make a crochet beanie to fit. I’m going to deal with a lot of theory. Theory seems unimportant until you want to venture out on your own without the comfort of a pattern. Then a basic knowledge will stand you in good stead to make just about anything. Let’s do it!

Quick note: I make reference to the crown of the beanie a number of times, and that is what is critical for us to calculate. When crocheting a beanie the crown is made to fit up to the widest part of the head by crocheting a flat disc shape using increases. When we reach the size we require we stop increasing (usually) and continue with the number of stitches in the last round. This will then allow us to start working down creating a dome shape that will fit the head.

The scary maths part

Often on crochet groups I note that people aren’t certain of the maths terminology needed to do the calculations. Please don’t run away! Bear with me. It’s so simple once you know it. Here we go.

Working on the assumption that a beanie is basically circular, and our heads (bear with me!) have a circumference proportionate to the beanie we want to make we will use the geometry of a circle for reference. Let’s chat about the names of the parts we will use. Then I will give real-world examples of how to use them.

The circumference of a circle is the measurement of the outside., so basically the distance around.

The radius of the circle is measured from the center of the circle to any point on the outside of the circle. This value will be the same no matter where you measure.

The diameter of a circle is measured across the center of the circle from any two points along the outside in a straight line. The diameter is thus made up of two radii (plural of radius).

There’s a lot of other maths around the geometry of a circle, but we won’t really need that. The next important thing I need to tell you is about Pi, for which the symbol is π. Yes, pronounced just like the pie you eat. Yum! Same same. At least as far as shape is concerned.

Pi / π (this is Greek, and you see they weren’t just in casual repose scoffing grapes all day) is defined as the ratio of the circumference of the circle to its diameter. The beauty is that this ratio is the same for every single circle out there. Yep. Every one. That ratio is 3.14159… It’s a long number. Point is for our purposes we can simplify it down to 3.14.

By now I hear you wondering what on earth this has to do with making a beanie? Well, let’s put this into practice.

Putting theory into practice – the less scary part

If I take the measurement of my head, above the eyebrows and measure the circumference (this works in both metric and imperial) and let’s say it’s 57cm. I now divide my 57cm by pi (see above) which we’ve simplified to 3.14, so 57 / 3.14 = 18,15286624203822. Another big number. But don’t worry. Remember anytime you divide a number by a number with two decimal places it can get icky. We’ll simplify it down to 18cm (about 7 inches). What this tells me is that the crown of the hat must be about 18cm in diameter (give or take).

So let’s sum that up. To measure what the crown of the beanie should be we do this calculation:

Circumference of head / 3.14 = diameter of crown.

Another thought on rounding, if the stitch pattern is very tight I’ll likely round up, and if it’s quite stretchy I may round down. You should have a feel for what will work for the stitch pattern you intend to use.

This will work in both metric and imperial. The reason for that is that 3.14 is a ratio, so it really doesn’t matter what the base number you use is. You may just want to consider how much you round up or down by as if your base number is smaller (as in imperial) it will make a difference.

If you want a beanie with a snug fit you can also deduct about 2-3cm (about an inch) from the head circumference and then calculate the crown. This will ensure that you have negative ease (allowing it to fit more tightly).

With crochet we usually (not always, but usually) work from the top down starting with a flat circle. The flat circle will form the crown of our hat. The maths above works perfectly for this.

Assuming you’ve stayed with me thus far, we’re almost ready to crochet! Just a wee bit more theory first.

A bit of crochet theory…

Getting the circle of the crown to lie flat

Tension

Let me deal with the first and most obvious possible issue. If you follow the instructions for increasing to a T, but your crown buckles, make sure that your increases are correct, and if they are, address tension as a possible cause. If your tension is too tight your crown will not lie flat.

Now it doesn’t need to be flat as a pancake. A little curving is okay, but if it is totally convex, nope. I would recommend that if this happens you go up a hook size until it’s a bit flatter. This does mean starting again, but fortunately, you should see this happen three or four rounds in, if it happens at all. No number of sacrifices to the gods will fix it, so frog it and move on with your life.

The theory of increases

The theory of how we increase is we will start with a magic circle or chain joined to form a circle. Into the circle we will place a number of stitches. Let’s say it’s 12. In the next round we will increase by working two stitches into each stitch, which in this case will give us 24. So far so good. In round 3, we will work an increase (two stitches into one stitch) and then a stitch into the next stitch. We will repeat this and it will give us a total of 12 increases (totalling 24) and 12 stitches, which gives us a grand total of 36 stitches. In round 4 we will work an increase followed by a stitch in each of the next two stitches. We will repeat this all the way around giving us 48 stitches. In round 5 we will work an increase followed by a stitch in each of the next three stitches, and repeat this, giving us a total of 60 stitches. The number of increases will always be the number you initially crocheted into the circle. And the distance between them will usually increase by an additional stitch per round between increases from the previous round. You could do this in perpetuity. Fortunately we’re only making a beanie!

Using my handy measuring tape I will stop when the crown reaches as close to the diameter I calculated earlier. In this case 18cm. Then in theory I will stop increasing and work the same number of stitches for the subsequent rounds as I did on the last round of the crown until I reach the length I want the beanie to be. Generally speaking, this is measured from the top of the head to the base of the ear. When your beanie reaches this total length, you can fasten off. I must mention that you may want it longer, or shorter. You may want to add ribbing that folds over. There are myriad ways you might style a beanie, so the above is just a guideline.

Can we crochet now? Why, yes. Did you take the measurements of the head circumference and the length from top of head to base of ear (if that’s how long you want it)? Yes? Let’s go.

Petals & Posts Beanie Pattern

If you head on over to Ravelry, you can download the free pattern that will give you the exact steps for making your own Petals & Posts Beanie. You will find that the theory above will help understand the pattern. It’s a breeze to make, and so quick.

download now

If I don’t speak to you again before we celebrate Christmas, I wish you all a very happy and peaceful festive season, whatever you may be celebrating.