Must-Know Sock Knitting Technique: How a Sock is Supposed to Fit

I am so disappointed when I knit something that doesn’t fit. Aren’t you? There are some patterns where you don’t have to worry about fit a lot, such as scarves and cowls, but most patterns need a little thought about how they will fit the recipient. Sock knitting is included in that category. Although you may think you need to know just the length of the feet of the person you’re knitting for, you would be wrong. Sorry.

Kate Atherley, author of, Custom Socks: Knit to Fit Your Feet, and stars in the video workshop, Knit Socks that Fit, is here today to talk in-depth about sock knitting and fitting, and the measurements you’ll need to make them perfect every time.

sock knitting

Harcourt Socks from Custom Socks by Kate Atherley

Here’s Kate to tell you more about knitting socks that fit.

How a Sock is Supposed to Fit

Yes, it’s true! We’re releasing a whole book on the topic of sock fit. (It’s not just about how to fit a sock, but the book also provides lots of great patterns and tips on how to customize a sock knitting pattern for special fit needs.)

Sock fit matters for two reasons: comfort and longevity. If you’re going to go to the trouble of knitting a pair of socks, they should fit you properly. A well-fitted sock is more comfortable to wear, and will last much longer.

Socks should be worn with a little bit of negative ease—that is, they should be smaller than the foot (and leg) they’re to cover. You want the sock to have to stretch a bit so that it will stay up on your leg and stay in place on your foot. A common problem cited with handknitted socks is that the legs don’t stay up—in many cases, this is simply because the sock is too big.

sock knitting

Marpleridge Socks from Custom Socks

A handknitted sock (especially one made out of wool or other animal fibers) will stretch out over the day. Unless the sock stretches somewhat to fit your foot, this added stretch can cause the sock to become floppy as the day wears on. In addition to feeling uncomfortable, loose floppy socks will move around inside shoes and wear out much quicker due to the added friction. A sock that has to stretch to fit your foot will stay put, feel comfortable, and resist abrasion.

For the best fit, a sock for an adult should measure about 10 percent—practically speaking, that corresponds to about 1” (2.5 cm)—smaller than the actual leg or foot circumference, and about 1/2” (1.3 cm) shorter than the actual foot length. A sock for a child should also measure about 10% smaller in circumference—about 1/2” (1.3 cm) for a foot with a 5” (12.5 cm) circumference—and about 1/4” to 1/2″ (6 mm to 1.3 cm) shorter in length.

If you haven’t been choosing your sock size based on these rules, chances are that you haven’t enjoyed well-fitting socks. Follow these guidelines for your next pair of socks and you’ll find an instant improvement in fit, even if you’re following a standard sock knitting pattern.

How Sock Knitting Patterns Are Sized

The finished size of the majority of sock patterns—whether they’re knitted toe up or top down—is based on the foot or ankle circumference. This makes sense—the socks have to fit around the foot and ankle, whereas the foot length and the leg length can be easily adjusted by working more or fewer rounds.

When we talk about foot circumference, we mean the measurement taken around the ball of the foot, which is typically the largest circumference, discounting any bunions. You don’t want to include a bunion in this measurement because that bony protuberance typically occupies less than 1″ (2.5 cm), or 10 percent, of the foot circumference or foot length. The inherent stretch in knitted fabric will accommodate this amount of variation. If you based the sock size on that larger circumference, the sock would be too big for 90 percent of your foot. This is why it’s good to be a knitter—we make a fabric that stretches. A sock with 10 percent negative ease will still stretch to fit comfortably around an area that’s a bit larger.

When we talk about ankle circumference, we mean the measurement around the narrowest part of your ankle—usually just above those characteristic rounded bones.

sock knitting

Jarvis Socks from Custom Socks

Most sock patterns assume that the wearer’s foot circumference and ankle circumference are the same. (Note that some sock patterns call this measurement the “leg circumference”—it’s because for the majority of calf-length sock patterns, the circumference of the sock leg is constant from top of cuff to the top of the heel, so either term works.) So, assuming your foot confirms to this standard, you can base your size on either measurement. But, remember that you want to allow for negative ease, so the finished size that you want to follow should be 10 percent—that’s about 1” (2.5 cm) for an adult sock—smaller than your actual foot or ankle circumference.

Not all sock patterns provide the same sizing information. Ideally, you want to know the “finished” measurements or “actual size” of the sock. This will tell you exactly what to expect in the knitted sock. Sizes that are described as “to fit” or “foot size” describe the foot intended to wear the sock, not the actual sock measurements. Unless you know exactly how much (if any) negative ease is allowed, these measurements won’t tell you the actual size of the finished sock.

If the sock sizes are given as ankle or foot circumference:

Choose a size that has about 10 percent negative ease—about 1” (2.5 cm) for an “average” adult sock; about 1/2″ to 1/4″ (6 mm to 1.3 cm) for an “average” child’s sock.

If the sock sizes are given as shoe size:

First check where the pattern was published—shoe sizes differ regionally and a U.S. size 7 shoe is different than a UK size 7 shoe.

In general, shoes are designed with the expectation that a longer foot (larger shoe size) corresponds to a larger foot circumference and shoe sizes assume that the foot has an “average” or medium width. If your foot is narrow, you’ll probably find the socks too big; if your foot is wide, you’ll probably find the socks too small.

sock knitting

Man of Aran Socks from Custom Socks

The only way to know for sure what the finished sock will measure around the foot or leg, is to divide the number of stitches in the foot or leg by the number of stitches per inch in the stitch pattern used (assuming the stitch gauge for the pattern used on the foot or leg is provided).

For example, if the pattern calls for 68 stitches in the foot or leg and the gauge is 8 stitches per inch (2.5 cm), the finished sock will measure about 8” (20.5 cm) in circumference.

68 stitches ÷ 8 stitches/inch = 8.5″

If the sock sizes are given as foot length:

Be careful. The typical assumption is that foot circumference increases proportionally with foot length. But the relationship isn’t this simple. If the pattern doesn’t include the finished foot or leg circumference, you’ll want to calculate it yourself based on the number of stitches and the gauge. If you can’t find (or calculate) the finished measurement, these patterns are best avoided.

If the sock sizes are given as standard names, “small,” “medium,” “large”:

Again, be careful—if there’s no indication of the actual size, you can’t be sure of what you’ll get unless you can calculate the finished measurement from the stitch count and gauge.

If the sock only has one size:

Beware—one size does not fit all! Unless the finished measurement is also given, there’s no way to know how it will fit unless there’s enough information for you to calculate the finished measurement yourself.

All of this is to say that you need to know your measurements and the finished measurements of the sock—foot and leg circumference and foot and leg lengths—to know if a knitted sock is going to fit.

—Kate Atherley, Custom Socks: Knit to Fit Your Feet

This info is so helpful. I don’t knit a lot of socks, and part of the reason why is that they haven’t fit me properly. They are either too tight on the calf or I have to really tug them over my heel to get them on. So I choose my store-bought socks over my handknits, which is super sad, right?

sock knitting

Lindisfarne by Kate Atherley, from Custom Socks

Kate is a sock knitting superstar, and her new resources are must-haves if you’re a sock knitter or you want to become one.

Start knitting socks that fit with Custom Socks: Knit to Fit Your Feet, in book or eBook format, and check out Kate’s wonderful video workshop, Knit Socks that Fit: Create Patterns Using Precise Measurements and Gauge, available as a DVD or video download.

I know I’ll be using these references and patterns. Here’s to socks that fit!



(Originally posted on July 15, 2015; updated on May 2, 2019.)

Get started on your dream socks!


  1. anita r at 7:57 am May 6, 2017

    I really wanted this book .I order the ebook wish I had gotten the book sent by regular mail. Some pages will not load. Makes it hard to scroll up&down to figure out what you are taking about . I’m a beginner sock knitter . I have knitting 4pairs so far. Some socks fit some don’t so I ordered this because you made it seem like it could really help. If I could make heads or tails out of the few pages I can down load I might help . Guess I should have gone to the book store that way I can see what I’m buying.

  2. Arlene B at 12:36 pm September 2, 2017

    If you cast on 68 stitches and the gauge is 8 stitches = 1 inch, then the circumference will be 8 .5 inches not 8 inches. I see an error in your instructions.

  3. Ellen C at 2:14 pm September 2, 2017

    What is the name of the pattern in the top photo?? All the others tell you but not the top one.

  4. Anonymous at 9:36 am August 15, 2018

    Hello there. Was just about to highly praise you, when I scrolled down to end of article and found out that not many subscribers are having great things to say about using the e-book, etc. BUT, I’ll still give you praise as you are indeed, the very first writer (from Interweave), who has used math to explain and go about getting perfection where the “fit” of a sock is concerned. I love math and these calculations are good to know, rather than relying on the drawn out outline of a niece’s or nephew’s foot. Have already printed off the complete article and 3-hole punched it in order to put in my binder at home. Does the book (or e-book) have more calculations than what is in the above article? Am thinking of ordering it later down ‘n the month. Right now, for me socks are a quick turn-round “Gift”, especially as I’ve conquered TAAT socks (or, using Magic Loop); since January have made six pairs using technique above, mainly for myself and my son. With your information above I can now only have a person’s foot length and circumference and be able get perfection (or close), without having the foot drawing outline. Also, some people are not into measuring, and your info. about using the shoe size is just wonderful…. great stuff, thanks so very much!!

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