Sock thickness and shoe fit

Short answer: A thick sock takes up to five millimetres in the shoe, which is roughly half a size. That means the thickness of your sock can change how a shoe fits, for better or for worse.

How much a sock takes up

A sock fills the space under the foot, over the instep and around the heel. Depending on thickness that is two to five millimetres, and the difference is clear in a snug shoe. Three or four millimetres sounds small, but in a shoe with a firm shape it equals going up or down half a size.

What thickness does to the shoe

A thick sock can make a perfectly fitting shoe tighter over the instep. It can also push the toes forward until they meet the front of the shoe. At first that is a small annoyance, but after a day it can mean sore toes. The sock is part of the shoe's fit.

The instep and the toes

The instep and the toes are the two places where a wrong sock shows first. Over the instep sit laces or straps, and there is little air. At the front the toes need room to move. If the sock is too thick that room disappears, and the foot is held tight instead of resting.

Buy shoes with the sock you will wear

Always try new shoes with the kind of sock you plan to wear. If you try with a thin sock and wear a thick one, the shoe is too small. Bring a pair of socks to the shop. For an everyday example, see bamboo socks for men.

Try shoes in the afternoon

The foot is largest late in the day, because it swells a little after hours on your feet. Try shoes in the afternoon or evening so you do not buy them too small. Walk around the shop and check that the toes have room and the heel stays put.

When the shoe is already bought

If the shoe is already bought, the sock can still help the fit. If the shoe is tight, choose a thin sock that gives you some air. If it is a little big, a thicker sock can fill it out so the foot does not slide. For daily wear, bamboo socks for women are one option.

When the shoe is too tight

A thick sock will not improve a shoe that is too tight. Switch to a thin model and see whether the pressure over the instep and in front of the toes eases. A very thin sock such as a footie gives the most room. See bamboo footies for men if the shoe is low and snug.

When the shoe is a little big

If the shoe is a little big, a thicker sock can help. It fills the space so the foot does not slide back and forth, which reduces friction at the heel. It is more of a stopgap than a fix, though: if the shoe is much too big, you need a smaller size.

Can a thick sock make the foot cold

Yes, if it squeezes the foot so much that blood flow drops. A thick sock in a shoe that is too tight is therefore often cold despite being thick. Air and freedom of movement keep warmth better than pressure. Choose a sock that leaves the foot room. If you have circulation problems, talk to your doctor.

Frequently asked questions

Can a thick sock make the foot cold

Yes, if it squeezes the foot so much that blood flow drops. Choose a sock that leaves the foot room, and let the thickness follow the fit of the shoe.

How much does a sock take up

Two to five millimetres, depending on thickness. That is up to half a size, and it can change how the shoe sits over the instep and in front of the toes.