Adult Sock Size Chart (Foot Length)
Unlike a sweater's chest measurement, adult foot sizing genuinely only has one half of its needed data published as a standard chart — foot length follows a real, consistent industry convention; foot circumference doesn't, and needs to be measured directly no matter which length band applies.
The chart
| Size label | Foot length |
|---|---|
| Adult XS | 8.5–9 in |
| Adult S | 9–9.5 in |
| Adult M | 9.5–10 in |
| Adult L | 10–10.5 in |
| Adult XL | 10.5–11 in |
| Adult 2XL | 11–11.5 in |
| Adult 3XL | 11.5–12 in |
Why circumference isn't on this chart
Foot width varies independently of length more than most other body measurements do — two people with an identical foot length can have noticeably different foot width, which is exactly why no standard chart exists for it the way this table exists for length. Measure the actual foot's circumference directly around the ball of the foot (the widest point) rather than estimating it from length alone.
Turning both measurements into a real sock
This site's socks project pages work through the full cast-on and yarn math using this chart's real length figures paired with an illustrative circumference, at a stated gauge — a useful worked example to check your own numbers against before starting a real pair, especially since a narrow rib-cuff stitch count is unusually sensitive to gauge at sock scale.
Heel and gusset sizing beyond length and circumference
Foot length and circumference get a sock most of the way to fitting, but heel depth and gusset width are a third dimension neither column above actually captures. The adult-plus sock page walks through exactly what goes wrong when a gusset sized for a narrower foot gets reused unchanged on a wider one — check that proportion against the real foot, not just this chart's two headline numbers.
Why socks are less forgiving of a size mismatch than most projects
A hat or sweater with slightly generous ease is often still comfortable; a sock sized meaningfully wrong at the foot is a real daily discomfort worn directly against skin and inside a shoe. This is part of why measuring directly, rather than estimating from a chart alone, matters more for socks than for almost any other project type on this site.
FAQ
Is there a separate baby and child sock chart, or does the same source cover those ages? This site's baby & child sizing chart and toddler & child chart both include their own foot-length columns, following the identical body-measurement convention as this adult chart, scaled to those younger age bands.
Does shoe size convert directly to a foot-length measurement on this chart? Not reliably enough to skip a real measurement — shoe sizing schemes vary by brand and region in ways that don't map cleanly onto a linear foot-length figure, so a direct foot measurement is worth the extra minute over converting from a shoe size.
How much negative ease should a sock cuff use relative to foot circumference? Commonly around three-quarters of an inch less than the measured circumference, enough for a ribbed cuff to grip the leg without sliding — see the adult sock project pages for the full worked cast-on math using this specific ease figure.