Knitting 101 – Hats: The Calculations

The swatch doesn't need to be quite this big, but you do want at least 4 inches by 4 inches.

The swatch doesn’t need to be quite this big, but you do want at least 4 inches by 4 inches.

Now that you know all the technical stuff – how to knit, what tools to use, various kinds of yarn, etc. – let’s have a little fun. How about we cast-on a project?

I’m getting a little ahead of myself. We’re not going to just cast-on the project. We’re going to go step by step through the whole process of knitting a project.

What are we going to make? I’m really not a fan of scarves for first projects. I think hats are a great place to start. There are so many lessons to learn with it. There’s knitting in the round (easier than it sounds), ribbing, and decreasing. Not to mention, when you’re done, you have a great accessory.

What You’ll Need:

  • Yarn: Any weight, any color, and any fiber you desire
  • Needles: You’ll need two sets of DPNs or circular needles (remember to have a fairly long cable if you go with circs). One you’ll find by making a gauge swatch. The other one will need to be 2 sizes smaller.
  • Stitch markers: This is for later in the project. You won’t need them until the crown.
  • Blunt needle: This is also for later, when we’re casting off.

Part One – The Calculations

We have to start at the beginning – the gauge swatch. I know, it’s not that fun.

Grab your yarn and some needles. It doesn’t matter what weight yarn. Knit a couple of swatches (for more information about that, check out Knitting 101: Reading a Pattern) to figure out how you want your fabric. Smaller needles make a tighter fabric, and larger needles will give you looser fabric. Don’t forget to wash and block your swatch.

Measure how many stitches are in 4 inches. Do some division to find out about how many stitches you have per inch. Now, measure your head. Wrap the tape measure around the back of your head and around your forehead, where the hat will sit. This is going to be so much easier to use than you might think. I was scared of math in knitting, but it’s basic algebra.

(Number of stitches per inch) x (your head measurement) = the number of stitches you need to cast on

If your number of stitches per inch is a fraction/decimal, round down. Take a look at your total number of stitches to cast on. This next part is my personal preference, not so much a rule. Is your total divisible by four? If so, you’re good. If not, round down to the nearest multiple of four.

With your smaller needles, cast on that total number.

Next week, we’ll get started on the actual knitting. I’ll go over knitting in the round, both on circs and on DPNs (which aren’t terribly different).


11 thoughts on “Knitting 101 – Hats: The Calculations

  1. This s a great post. I’ve knitted for years, but only reluctantly swatch, which is dumb. 🙂 so, have you seen any projects that combine or make something out of previous swatch patches? That might help motivate me to do it right…

  2. I’ve just tuned in here, and I’m so glad I did. Like Leah I have also knitted for years, but I never get very technical about anything I do. Looking forward to learning all the right steps.

  3. I love hats for beginners, along with the great points you mentioned, the fact that they can be done so much quicker than a scarf helps especially in the beginning. I’m so glad you are taking the technical approach to creating, it will allow you to be able to branch out into other items that much quicker and easier.

  4. Hi! Question: how come you use needles that are 2 sizes smaller after you swatch it? I’ve been using the same formula for hats but they keep turning out too big (even after I made a swatch!), so I’m thinking this would help but am curious as to how it works!


    • Hi! You’re going to use two sets of needles when making a hat (generally; that may change depending on the pattern. The one that is 2 sizes smaller is for the brim so that the hat fits nice and tight.

      It sounds like you’re having a similar problem that I always run into. I’ve found that, no matter the hat pattern (or any pattern), I have to consistently start with a needle 2 sizes smaller than what’s called for. So if the brim is meant to be size 6 and the rest if that hat size 8 according to a pattern, I grab my 4s and 6s.

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