Loosely cast on 60[66, 72, 80] sts. Distribute stitches as you prefer and join, being careful not to twist. Mark beginning of round.
Round 1: Work chart row 1 for appropriate size around round. Note that size XL uses the same chart as for size S.
Work as established following appropriate size. Once 50[56, 62, 50] rounds are complete, continue repeating only chart rows 27-50[29-56, 31-62, 27-50], working until leg is desired length. The socks photographed have legs 7 inches long.
Heel Flap:
Turn so that WS is facing. Heel flap is worked back and forth in rows on 29[32, 35, 39] sts.
Row 1 [WS]: K3, p26[29, 32, 36].
Row 2 [RS]: P3, [k1, sl 1], rep to last 3 sts, k3.
Repeat Rows 1 & 2 15[17, 18, 19] more times. 32[36, 38, 40] rows total. WS will be facing.
This heel flap style creates a garter stitch edge which makes it easy to pick up the gusset stitches along the edge of the heel flap.
17[20, 21, 23] sts remain after heel turn.
Pick up and knit 18[19, 20, 21] sts along the side of the heel flap for right gusset. Place marker for start of round. Work across 31[34, 37, 41] instep sts following next row of appropriate chart for size being made and place a second marker for end of instep. Pick up and knit 18[19, 20, 21]sts along the side of the heel flap for left gusset. Knit the 17[20, 21, 23] heel flap stitches and the 18[19, 20, 21] right side gusset stitches. 84[92, 98, 106] sts total. 31[34, 37, 41] on instep, 53[58, 61, 65] on sole. Start of round is at start of instep sts.
Gusset decreases:
Decrease round: Work in pattern to end of instep; k1, SSK; knit to last 3 sts of round, k2tog, k1. 2 sts decreased.
Following round: Work even.
Repeat the above two rounds 11[12, 12, 12] more times until 60[66, 72, 80] sts rem total – 31[34, 37, 41] on instep, 29[32, 35, 39] on sole.
FOOT
Work even as established on 60[66, 72, 80] sts until the foot length reaches the base of the toes when measured from back of heel, removing instep markers on final round.
TOE
Setup round: K30[33, 36, 40], place marker for end of instep sts, k to end of round.
Decrease round: K 1, ssk, knit to 3 stitches before second marker, k2tog, k2, ssk, knit to 3 sts before end of round, k2tog, k1. 4 sts decreased.
Round 2: Knit.
Repeat these two rounds [7, 8, 9, 9] times more, until 28[30, 32, 40] sts remain.
Repeat decrease round 3[3, 3, 4] more times until 16[18, 20, 24] sts remain.