Socks are one of the few clothes where the label is based on someone else’s shoe size. You will see small, medium and large, or numbers like 9–11, and each brand decides which shoe sizes fall into each size. This calculator takes your US shoe size and gives the sock size from a published chart, along with the matching slipper sock size.
How to use the sock size calculator
- Choose men’s or women’s. The same number is a different size in the two systems.
- Enter your US shoe size. Half sizes are fine; other values are rounded to the nearest half size.
- Read the sock size and the range of shoe sizes it covers.
- Check the slipper size if you are buying gripper slipper socks, which use a different ladder.
Sock size formula
sock size = the row of the chart whose range contains that shoe size
There is no arithmetic formula for sock sizes; the ranges are a lookup, set by the brand. The values below are from the Bombas adult size chart as published by the retailer Scheels (retrieved 2026-10-16), and the “all sizes” table is generated from the same ranges.
| Group | Sock size | US shoe size | Slipper sock size | US shoe size (slipper) |
|---|---|---|---|---|
| Women’s | S | 4 – 7.5 | XS | 5 – 6.5 |
| Women’s | M | 8 – 10.5 | S | 7 – 8.5 |
| Women’s | L | 11 – 13 | M | 9 – 11.5 |
| Men’s | M | 6 – 9 | M | 7 – 9.5 |
| Men’s | L | 9.5 – 13 | L | 10 – 12.5 |
| Men’s | XL | 13.5 – 16 | XL | 13 – 15 |
Sock size for each shoe size
| US shoe size | Women’s sock | Women’s slipper | Men’s sock | Men’s slipper |
|---|---|---|---|---|
| 5 | S | XS | — | — |
| 6 | S | XS | M | — |
| 7 | S | S | M | M |
| 8 | M | S | M | M |
| 9 | M | M | M | M |
| 10 | M | M | L | L |
| 11 | L | M | L | L |
| 12 | L | L | L | L |
| 13 | L | L | L | XL |
| 14 | — | — | XL | XL |
Worked example
You wear a women’s US 8.5.
- Women’s regular socks: medium covers 8 to 10.5, so 8.5 is a medium.
- Women’s slipper socks: small covers 7 to 8.5, so 8.5 is the top of the small range. If you want a roomier slipper, check the medium, which starts at 9.
Getting the fit right
- Boundaries matter most. The edge of a range, such as women’s 7.5 and 8, is where a sock is tightest or loosest.
- Heel and toe. The heel pocket should sit under the heel, and the toe seam should not press on the toes.
- Different shoes. Tight boots and cycling shoes (see the Cycling Shoe Size Calculator) reward a snug sock; slippers reward a roomy one.
- Convert if needed. If your shoe size is European or UK, use the Shoe Size Converter (US/UK/EU/JP) first.
The result is general guidance from one brand’s chart. For tights, see the Tights Size Calculator.
Sources
Every figure above comes from these pages, read directly on the date shown. Brand names are used only to identify published charts.
- Scheels — Bombas adult socks size chart (regular socks and gripper + bootie slippers, women’s and men’s US shoe size) — retrieved 2026-10-16
Frequently asked questions
How do I find my sock size?
Sock sizes are matched to shoe size, not to foot length. Enter your US shoe size, men’s or women’s, and the calculator reads the size from a published Bombas chart: for example women’s 8 to 10.5 is medium and men’s 9.5 to 13 is large.
Do all brands use the same sock sizes?
No. Each brand draws its own boundaries, and some use numeric ranges such as 9–11 instead of letters. This page is based on one brand’s chart, so use the brand’s own table when you buy from it. See the Shoe Size Converter (US/UK/EU/JP) if your shoe size is in another system.
What if I am between two sock sizes?
Look at how the sock is made. A snug sock that stretches fits better than a loose one that bunches inside the shoe, but a heel that sits too high or a toe that pulls tight means you need the larger size. Half shoe sizes are rounded to the nearest half size here.
Why are slipper sock sizes different?
Gripper slipper socks have a thicker base and a smaller number of sizes, so each size covers fewer shoe sizes. The same Bombas chart lists women’s XS to L (US 5 to 14) and men’s M to XL (US 7 to 15).
Why does the calculator stop at certain sizes?
The chart covers women’s US 4 to 13 and men’s US 6 to 16 for adult socks. Smaller feet need a kids’ or baby chart, for example the Kids Shoe Size Calculator, and larger feet need a brand that makes extended sizes.