Sock guide

Which sock size
should you choose?

Shoe size, size ranges, the right fit: how to find the pair that neither slips nor pinches.

✔ By shoe size✔ The right fit✔ Between two sizes

Sock size is based on your shoe size. Most brands sell socks in size ranges, for example 39-42 and 43-46. A well-chosen sock has its heel exactly on your heel and a toe that doesn't pull on your toes. Too small, it slips under your heel and wears quickly at the toe, too big, it bunches up in the shoe. Between two ranges, the material and thickness decide.

At a glance

Which range for which shoe size?

The most common ranges. The size shown on the packaging is what counts, as it varies from brand to brand.

Shoe sizeUsual rangeGood to know
39 and 4039-42At the bottom of the range, the sock may feel a little loose
41 and 4239-42Usually an ideal fit
43 and 4443-46Usually an ideal fit
45 and 4643-46At the top of the range, a stretchy material helps
One sizeWide range, check the packagingPractical, but less precise at either end

The right fit

How a sock should fit

Four points to check when you put on a new pair.

  • The heel of the sock sits exactly on your heel, without riding up towards the ankle
  • The toe doesn't pull on your toes or form a fold at the front
  • The cuff holds without leaving a deep mark on the skin
  • Inside the shoe, nothing slips or bunches up

Between two sizes

Is your shoe size on the borderline?

If your shoe size sits on the borderline between two ranges, for example 42 or 43 depending on the shoe, it is best to choose the larger range for thin socks in cotton and polyester: a little extra room evens out, whereas a sock that is too small soon wears at the toe and slips under the heel. For thick socks worn in close-fitting shoes, the smaller range may be more comfortable.

Best avoided

The most common mistakes

The wrong size is rarely noticed the first time you wear it, but it soon shows in the wear.

Choosing too small

The sock slips under the heel and pulls on the toes.

Result: holes at the toe, rapid wear

Choosing too big

The fabric bunches up under the foot and at the heel.

Result: friction in the shoe

Going by just one pair of shoes

Shoe sizes vary from one shoe brand to another.

Result: wrong range chosen

Ignoring the cuff

Too tight, it marks the skin, too loose, it slips down.

Result: discomfort, sock slides down

When UNDY is the right fit

The right size, every month

So you never pick the wrong range again.

The right size, every month

At UNDY, you enter your exact shoe size, from 39 to 46, and every pair is chosen accordingly. You can change your size at any time in your customer account. Most models are made of cotton blended with polyester.

For yourself

Sock subscription

One pair of branded socks a month, in your size, cancellable at any time.

from CHF 12.50
per month · free delivery
View →
To give

Sock gift

The recipient chooses their own size on activation. 3, 6 or 12 months.

from CHF 39.90
3-month term · no automatic renewal
View →

Frequently asked questions

What people often ask

Which sock size for a size 42 shoe?
Usually the 39-42 range. If some of your shoes are a 43, the 43-46 range can also work, especially for thin socks.
Do socks follow the same sizing as shoes?
They are based on European shoe sizes, but in ranges. The size shown on the brand's packaging is what counts.
What should I do if I'm between two sizes?
For thin socks, go for the larger range. For thick socks in close-fitting shoes, go for the smaller range.
Do socks shrink in the wash?
Cotton can shrink a little in heat. Washing at 30 or 40 degrees and air drying keep this to a minimum.
Is there a reliable conversion to UK or US sizes?
Conversions vary from brand to brand. The safest approach is to start from the European size shown in your shoes.
Do I need to know his shoe size to give UNDY socks?
No. With the gift, the recipient enters their own size on activation.

Read more

Other useful pages

Sock guide →How to wash your socks →Why socks get holes →Which boxer size should you choose? →Avoiding multipacks in the wrong sizes →

Socks in your size, every month.

From CHF 12.50 a month, sizes 39 to 46, delivered with free shipping.

View the sock subscription → Give socks