How to Measure Your Sock Size (US Shoe Size Chart)

You wear a US women's 7. You pick up a pack of socks and it says 9-11. Is that your size? Yes, as it happens, and the reason is that sock sizes and shoe sizes are two different measuring systems that happen to use similar-looking numbers. Here is how to work out your sock size properly, once, and never think about it again.

Sock size is not shoe size

Sock sizing came from the hosiery trade and is roughly based on the length of your foot in inches, measured from heel to longest toe. Shoe sizing is based on the length of the last the shoe is built on, which is longer than your foot, and it differs between men's, women's and every country you can name. The two systems drifted apart a long time ago and never came back together.

The practical consequence is that a single sock size covers a range of shoe sizes. That is not a manufacturer being vague; it is the sock stretching to fit. A knitted sock with a few per cent elastane genuinely does fit a two or three size span comfortably, which is why almost every pack you see is labeled as a range.

How to measure your foot in two minutes

1. Put a sheet of paper on a hard floor, up against a wall.
2. Stand on it, in bare feet or the thin socks you would normally wear, with your heel touching the wall. Stand up properly, with your weight on the foot, because feet lengthen when you put weight on them.
3. Mark the paper at the tip of your longest toe. On a lot of people that is the second toe, not the big toe.
4. Measure from the wall to the mark in inches.
5. Do the other foot too. Most people have one foot slightly longer and you should always size to the longer one.

That number is your foot length. Nine inches is roughly a US women's 7; ten and a half inches is roughly a US men's 9. Do not treat those as gospel, because manufacturers differ, but they give you a sanity check against the shoe size you already buy.

Reading the number on the pack

Once you know the US shoe size you actually wear, you can read any sock label. On our women's socks, a pack marked 9-11 is the sock size that corresponds to US women's shoe sizes 5 to 10. Some of our women's socks are labeled by shoe size directly, 5-10, which means the same thing. Men's bamboo dress socks are marked 8-11.5, which is a men's shoe size. Unisex styles use a wider band, 7-13, because they are cut to stretch across both.

The full breakdown, including one-size sheer socks and pantyhose in medium and large, is on our sock size guide. Every product page also states its own range, and that always beats a general chart.

What to do if you are between sizes

Go up. It is the right answer almost every time. A sock with a little room to spare sits properly, keeps its shape and lasts longer. A sock stretched to its limit does three bad things: it pulls the heel pocket out of position so the heel sits under your arch, it presses the toe seam against your toes, and it wears through at the ball of the foot far sooner because the fabric is under constant tension.

The one exception is very thin sheer hosiery, where a size too large will wrinkle at the ankle. For those, follow the sizing panel on the pack rather than your instinct.

Why the same size feels different in different fabrics

A cotton crew sock and a bamboo dress sock in the same nominal size will not feel identical. Thick cotton takes up more room inside a shoe and has more friction against your skin, so it feels snugger. Bamboo rayon is smoother and thinner and drapes closer to the foot. Nylon sheer socks stretch the furthest of all, which is why they can get away with being sold as one size. None of that is a sizing error; it is the material behaving as it should. If you are ordering a style you have not tried before, expect a slightly different feel at the same number.

One size, honestly

One size is real, but it has limits. It works for sheer ankle socks because the fabric stretches a long way and there is very little sock to go wrong. It works less well the more structure a sock has. Nobody sells a one-size hiking sock, and for good reason.

Sizing for tall socks

Knee-highs and slouch socks add a second measurement: your calf. Foot size gets the foot right; calf width decides whether the sock stays where you put it. There is a full explanation, including how to measure, in our guide to knee-high socks that actually stay up.

Where to start

Once you know your number, the rest is easy. Browse women's socks in shoe sizes 5 to 10, men's socks in 8 to 11.5, or the multi-pair bundles in value packs. Every CasMarkt order ships free within the US from our base in Flower Mound, Texas, and if the size is not right you have 30 days to return anything unworn in its original packaging.