Sock Size Calculator
KnittingPick a size or enter a foot measurement, add your gauge, and get every number for a cuff-down heel flap sock.
Quick answer. A woman's medium sock (8 in foot, shoe 7 to 9 1/2) at 30 stitches per 4 in needs a cast on of 52 stitches with 1 in of negative ease, a 26 stitch heel flap and a toe that starts about 8 in from the heel.
Source: Craft Yarn Council Foot Size Chart; ease and heel from Knitty's Socks 101; wedge toe from Interweave.
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Your sock, cuff down
Knit a heel flap, turn the heel, pick up for the gusset, then decrease every other round back to the cast on.
Sock size chart
Foot circumference around the widest part of the foot, sock height from where the heel turn starts to the top, and foot length from the back of the heel to the longest toe.
| Size | US shoe | Foot around | Sock height | Foot length |
|---|---|---|---|---|
| Baby, 6 to 18 months | 0 to 4 | 4.5 in (11.4 cm) | 2.5 in (6.4 cm) | 3 to 4.5 in (7.6 to 11.4 cm) |
| Toddler, 2 to 3 years | 5 to 9 | 5.5 in (14 cm) | 3.5 in (8.9 cm) | 4.75 to 6 in (12.1 to 15.2 cm) |
| Child, 4 to 5 years | 10 to 13 | 6 in (15.2 cm) | 4.5 in (11.4 cm) | 6.5 to 7.5 in (16.5 to 19.1 cm) |
| Youth, 6 to 9 years | 1 to 3 | 6.5 in (16.5 cm) | 5.5 in (14 cm) | 7.75 to 8.5 in (19.7 to 21.6 cm) |
| Youth, 10 to 13 years | 4 to 6 | 7 in (17.8 cm) | 6.5 in (16.5 cm) | 8.75 to 9.5 in (22.2 to 24.1 cm) |
| Woman, shoe 4 to 6 1/2 | 4 to 6 1/2 | 7 in (17.8 cm) | 6.5 in (16.5 cm) | 8 to 9 in (20.3 to 22.9 cm) |
| Woman, shoe 7 to 9 1/2 | 7 to 9 1/2 | 8 in (20.3 cm) | 7 in (17.8 cm) | 9.25 to 10 in (23.5 to 25.4 cm) |
| Woman, shoe 10 to 12 1/2 | 10 to 12 1/2 | 9 in (22.9 cm) | 7.5 in (19.1 cm) | 10.25 to 11 in (26 to 27.9 cm) |
| Man, shoe 6 to 8 1/2 | 6 to 8 1/2 | 8 in (20.3 cm) | 7.5 in (19.1 cm) | 9.25 to 10 in (23.5 to 25.4 cm) |
| Man, shoe 9 to 11 1/2 | 9 to 11 1/2 | 9 in (22.9 cm) | 8 in (20.3 cm) | 10.25 to 11 in (26 to 27.9 cm) |
| Man, shoe 12 to 14 | 12 to 14 | 10 in (25.4 cm) | 8.5 in (21.6 cm) | 11.25 to 12 in (28.6 to 30.5 cm) |
From the Craft Yarn Council Foot Size Chart. Centimetres worked from the inches.
Sock cast on by size and gauge
With 1 in of negative ease for adults and 1/2 in for children, rounded to a multiple of 4.
| Size | 28 sts / 4 in | 30 sts / 4 in | 32 sts / 4 in | 36 sts / 4 in |
|---|---|---|---|---|
| Baby, 6 to 18 months | 28 | 32 | 32 | 36 |
| Toddler, 2 to 3 years | 36 | 36 | 40 | 44 |
| Child, 4 to 5 years | 40 | 40 | 44 | 48 |
| Youth, 6 to 9 years | 44 | 44 | 48 | 56 |
| Youth, 10 to 13 years | 44 | 48 | 52 | 60 |
| Woman, shoe 4 to 6 1/2 | 44 | 44 | 48 | 56 |
| Woman, shoe 7 to 9 1/2 | 48 | 52 | 56 | 64 |
| Woman, shoe 10 to 12 1/2 | 56 | 60 | 64 | 72 |
| Man, shoe 6 to 8 1/2 | 48 | 52 | 56 | 64 |
| Man, shoe 9 to 11 1/2 | 56 | 60 | 64 | 72 |
| Man, shoe 12 to 14 | 64 | 68 | 72 | 80 |
Worked example: woman's medium
Foot 8 in around, 9.25 to 10 in long (we use 9.625 in), sock height 7 in. Gauge 30 stitches and 42 rounds per 4 in is 7.5 stitches and 10.5 rounds per inch.
- Cast on: 8 - 1 = 7 in x 7.5 = 52.5, nearest multiple of 4 = 52.
- Leg: 7 in x 10.5 = 73.5, so 74 rounds to the heel.
- Heel flap: half of 52 = 26 stitches; 3/4 of 26 = 19.5, up to an even 20 rows.
- Heel turn: 26 in thirds is 8, 10, 8; the centre 10 plus 2 leaves 12.
- Gusset: pick up 52 / 4 = 13 each side, for 26 + 12 + 26 = 64. Decrease 2 every other round 6 times, back to 52.
- Toe: a third of 52 is 17.3, nearest multiple of 4 = 16. (52 - 16) / 4 = 9 decrease rounds, 17 rounds in all, 17 / 10.5 = 1.62 in.
- Start the toe at 9.625 - 1.62 = 8 in (20.3 cm) from the back of the heel, then graft the last 16 stitches.
How the sock maths works
- Cast on = (foot circumference - negative ease) x stitches per inch, rounded to a multiple of 4
- Heel flap = half the stitches, for 2/3 (under 50 sts) or 3/4 as many rows, rounded up to even
- Gusset pick up = cast on / 4 each side, then decrease back to the cast on
- Toe = decrease 4 every other round to about a third of the stitches
- Toe length = (2 x decrease rounds - 1) / rounds per inch; start it at foot length minus toe length
Sources
- Craft Yarn Council, Foot Size Chart: foot circumference, sock height and foot length by size. https://www.craftyarncouncil.com/standards/foot-size-charts
- Kate Atherley, Socks 101, Knitty Spring 2005: negative ease, heel flap, heel turn and gusset. https://knitty.com/ISSUEspring05/FEATsocks101.html
- Roxanne Richardson, How to Customize Wedge-Shaped Sock Toes, Interweave: toe decreases and toe length. https://www.interweave.com/article/knitting/customize-wedge-shaped-sock-toes
Common questions
How many stitches do I cast on for socks?
For a woman's medium (8 in foot) at 30 stitches per 4 in, subtract 1 in of negative ease and cast on 52. A man's medium (9 in foot) at the same gauge is 60.
How much negative ease should socks have?
Kate Atherley's Socks 101 in Knitty subtracts 1 in (2.5 cm) for adults and 1/2 in (1.3 cm) for children, with typical sock yarn. Subtract less with much thicker yarn.
When do I start the toe?
When the foot measures the total foot length minus the toe length. A 52 stitch wedge toe at 42 rounds per 4 in is 17 rounds, about 1.6 in, so for a 9.63 in foot start it at about 8 in from the back of the heel.
How long should the heel flap be?
Work it over half the stitches, for 2/3 as many rows as heel stitches on socks under 50 stitches and 3/4 on bigger socks, rounded up to an even number. 26 heel stitches is 20 rows.
What size is a woman's medium sock?
In the Craft Yarn Council chart, women's shoe sizes 7 to 9 1/2: an 8 in (20.3 cm) foot circumference, 9.25 to 10 in foot length and a 7 in sock height.
Do sock sizes match shoe sizes?
Not exactly. The Craft Yarn Council charts group US shoe sizes, and it notes that sock size ranges overlap and do not correlate to shoe size. Measure the foot when you can.