How many stitches to cast on for socks?

Everything you need to know about sock measurements and cast on requirements for the most common sizes – man or woman.

Socks are one of the most popular knitting patterns. I certainly love making them. But there is one question you have to deal with whenever you start a new project: Just how many stitches do I cast on for a sock?

In this tutorial, I will show you everything you need to know about knitting socks that really fit – no matter the yarn, and no matter if it’s for a man or a woman. It’s no magic but it does involve some careful preparations if you want to do it right.

You see, depending on the yarn you pick and your very individual tension you will have to cast on a different number of stitches. And this is really important to realize: There are many socks charts and tables, and so on, and they are all nice and cute if you want a rough guestimation. But they rarely will result in socks that truly fit!

Instead, I recommend a simple and foolproof method to find out your own measurements. This is much more versatile and will achieve much better results. Because if you decide to knit bulky socks with a very heavy yarn the next time, then you probably will have to cast on a vastly different number of stitches.

For my easy men’s sock pattern I cast on 57 stitches for size 8.5. And for my basic ribbed sock, I cast on 87 stitches even though it’s the exact same size. The vast difference can easily be explained. I used a different yarn (fingering instead of DK weight) and different needle sizes (2.0mm instead of 3.0mm).

Just showing you a table with cast-on recommendations might be what most beginners are looking for. It just sounds so nice and easy. But anyone who tells you “Cast on 60 stitches for a woman’s size 6” is oversimplifying a very complex combination of quite a lot of different factors. And, believe me, I have seen my share of beginner socks in my 30+ years of knitting that ended up way too big or too small because someone wanted an easy answer.

So, here’s what I propose instead:

Tip: Check out my free knitting school for more tutorials & helpful guides. And read my tutorial on how to cast on with two needles in case you are looking for a super stretchy cast-on technique.

Step 1: Knit a swatch

First, you need to knit a little 7×7 cm swatch (or 5×5 inches) in the pattern of your choice. Maybe you want a 2×2 rib or stockinette stitch (both very nice stitches for socks). And once you bound off all stitches, you need to wash your little swatch and block it.

This is important because a lot of yarns will change after washing (some loosen up quite a bit). And if you don’t finish the whole process, your socks might end up too big after the first laundry despite all your diligent measurements.

Once your swatch is all dried up, you need to figure out your gauge. So, take a ruler (or a tape) and count how many stitches in a row you need to cover 5 cm (or 4 inches) right in the middle of your swatch.

Normally, you would have to measure out how many rows you need to cover 5 inches as well. But as long as you are not following a pattern and you don’t need to meet the row gauge – at least not for socks.

Note: The swatch has to be a bit bigger because knitting fabric tends to behave a little differently towards the edges (and your socks don’t have edges).

Step 2: Measure your foot

Next, you have to measure your foot at its widest part. I’ve seen a lot of tutorials telling you to measure it towards the toes or around the calf. But the way I see it, this leads to less than ideal results. Instead, for most people, the widest part will be around the ankle/heel. And, if you actually take your measurements, you will notice that the difference between the two is quite a lot – often as much as 4 inches.

Think of it like that: If you have a simple loop of yarn. What diameter should it have so you can squeeze your foot through all the way to your calf? I guarantee you, it won’t work if you didn’t measure the widest part.

Now, most sock patterns will have methods to make more room around the heel BUT the heel still needs to fit through the rest of your sock as you dress up. This means that every part of the sock that comes after the heel still needs to be big enough to let your hell pass through.

Note: Often men have a more pronounced heel and overall much more variation in the different circumferences than women.

Step 3: Do some easy math

Once you have your gauge and the circumference of your foot (or of the intended wearer) you need to do some very easy calculations. Now, don’t be scared. This will be really easy but a calculator will make things a bit easier.

1. Divide the number of stitches by the width you measured.
   e.g. 13 st / 5 cm = 2.6
2. Multiply the resulting factor times the circumference of your foot
   e.g. 2.6 x 34cm = 88.4
3. Factor in the maximum negative ease of your pattern. Around 10-15% for stockinette stitch and 15-20% for a 2×2 rib. So, multiply that number times 0.9 or 0.85, etc (if you are a loose knitter, take the higher number; if you are a tight knitter, the lower; also depends a bit on the stretchiness of your yarn).
   e.g. 88.4 x 0.90= 79.6
4. Round to the nearest number matching the repeat of your pattern work.
   E.g. in the case of a 2×2 rib, you need to cast on multiples of 4. So in my case, I’d have to go for 80 stitches.

This simple 4 step calculation will easily give you the number of stitches you need to cast on. The length you need to knit for the calves will then be determined by this circumference. Your cuff will have the perfect fit at the position where your calf has the same circumference.

Note: If your socks have a very complicated repeat or pattern (like 10 stitches wide or so), then rounding won’t cut it anymore. In this case, you might have to consider switching to one needle size bigger or smaller so you can fit in the repeat. Obviously, you would have to knit another swatch to verify your calculations.

Note 2: Just to make sure you understand the calculation a tiny bit better. Basically, what you are doing is finding out how many stitches you need to knit per inch/cm. Next, you use this number to figure out how large the opening of your sock needs to be so you can get it past the heel. But as this just concerns putting them on (as opposed to wearing them) you can make use of the natural stretchiness of the fabric – like a rubber band you would put around your calf.

Step 4: Cast on and knit a couple of rounds

Now here’s one more thing you need to know: Most knitters aren’t able to create knit and purl stitches with the exact same dimensions. So ideally, your swatch should be knit in the round. Why? Take stockinette stitch for example. If you knit it flat, you switch between knit stitches on the right side and purl stitches on the wrong side. But if you knit it in the round, you never end up purling a single stitch. And this will influence your gauge.

But here’s the thing: A truly reliable swatch knit in the round will be almost as big as the start of your sock. Also, different yarns behave quite differently, are more or less stretchy, etc.

That’s why I recommend knitting a flat swatch, figure out your cast on requirements, and then simply knit a couple of rounds. I always do around 20 rounds. And then you can simply slip your work in progress on a cable needle and try your socks on.

Don’t do this too early (like after 5 rounds). Most knitting stitch patterns will behave quite a bit differently when you only finished a couple of rows. And then, you will easily see if your calculations were right or if you still need to do some minor adjustments.

Further tips on figuring out the cast-on requirements for socks

In most cases, you probably won’t get it 100% right on the first attempt. But that’s quite normal. Shaping the perfect socks is an art and it requires a bit of patience. Here are some further helpful tips to find the final answer on how many stitches you need to cast on for socks.

1. Take notes of all your decisions (how many stitches you cast on, how and when you turned the heel, how many stitches you decrease after the heel if at all, etc). That way you can adjust everything for the second time and learn from your mistakes.
2. Stick to the same yarn base. Different yarns behave quite differently. And while casting on 80 stitches for men’s socks might be perfect with one yarn, it will be much too loose or narrow if you pick a different brand. But with the same yarn, you already know your gauge and you don’t need to knit another swatch.
3. Be aware that not all feet are shaped in the same way. Decreases and gussets can help to get a lovely fit for feet that show a big spectrum of different circumferences. For example, if you have a very narrow foot, nothing speaks against decreasing a couple of stitches after you turned the heel. And if you have very muscular calves, you might want to cast on 4 or 6 stitches more and decrease them again after a couple of centimeters further down your leg.
4. Pick a knitting stitch pattern that is quite forgiving at the start. In my opinion, the 2×2 rib is just perfect for that. Even if you end up with one size too big, you probably won’t notice it all that much (which is precisely the reason why commercial socks can be sold for a size range..like 6-7, etc).
5. Don’t be afraid to frog and remember to try on your work in progress frequently. Don’t knit them to the very finish and, only then, try them on. Slipping your WIP on circular needles with a long cable will be the easiest way to do that.
6. Don’t trust sock charts. And most importantly, the size alone will not help you. The shoe size just tells you how long a foot is, and, respectively, how long you need to knit that insole. But that has literally nothing to do with your cast on. The cast-on is only dependant on the circumference. This means, if you want to knit socks for someone else, you have to find out these measurements.
   Sock charts are usually okayish if you use the exact same yarn they were made for (some big yarn producers offer them). But for the rest, it’s not a lot better than guessing.

Further reading: How to do the single cast on

And that’s everything you need to know on how many stitches to cast on for socks! Feel free to comment below in case you have any questions.