The sock heel is the part of the sock, just below the cuff in the back, which covers the heel of your foot. While there are several different ways to knit a sock heel, the most durable are the ones that use slipped stitches.
Basic Heel Stitch
After you knit the cuff and the leg of the sock, you are ready to divide the stitches to knit the heel. The heel stitch is the most basic way to knit a sturdy sock heel.
The slipped stitches make the sock draw in and hug the heel of the foot, while also creating a thicker fabric.
The heel flap stitches will all be arranged on the same needle, so you can work back and forth, rather than in the round. The easiest way to divide the heel is to work half the number of stitches you cast on. For example, if you cast on 60 stitches, the heel flap will be worked over 30 stitches.
Because the heel flap is in the back of the sock, divide the remaining stitches in half and distribute them on the needles. For a 60-stitch sock, there would be 15 stitches on the first needle, 30 heel flap stitches on the second needle, and 15 stitches on the third needle.
Knit the stitches on the first needle in pattern. For example, if you knit the leg in stockinette stitch, then knit the stitches on the first needle in stockinette stitch.
Insert the right needle into the first stitch on the second needle as if you were going to purl it. This is called slipping a stitch purlwise. Knit the next stitch. Note that this is the right side of the heel that will be visible.
If you are worried that the stitches on the first and third needles will slide off while you are working the heel, use point protectors on the ends of the needles to hold the stitches in place.
Repeat Step 3 across the needle, slipping every other stitch. When you reach the end, turn the work. You will be knitting flat instead of in the round from now on.
Slip the first stitch purlwise, just as you slipped the first stitch in Step 3. Purl across to the end of the row.
Repeat steps 3-5 to knit the rest of the heel. Knit two-thirds to three-quarters as many rows as there are heel stitches. For example, if there are 24 heel stitches, work 16 rows of the heel flap.
After the heel flap is complete, you will need to turn the heel. This process involves creating a curve in the heel so that you can work the instep of the sock.
Knit the first two-thirds stitches of the heel flap. Slip the next two stitches as if to knit, then insert the left hand needle into the two stitches to knit them together. This is called the slip slip knit, or SSK. Turn the work. Notice that there are still some remaining heel flap stitches on the left needle when you turn the work.
Don't worry if your heel stitches will not divide evenly into thirds. For instance, if you have 28 stitches on your heel flap, you can divide them into uneven thirds of nine, ten, and nine.
Slip the first stitch, then purl the center one-third of the heel stitches. Insert the right needle into the next two stitches as if to purl, then purl them together. Turn the work.
Slip the first stitch, then knit the center one-third of the heel stitches. Make another SSK as you did in step 7, then turn the work.
Repeat Steps 7 to 9 until every stitch of the heel flap has been worked.
Eye of Partridge Stitch
This heel flap is similar to the Basic Heel Stitch, in that it provides a sturdy heel. However, the Eye of Partridge alternates the slipped stitches to create a lattice-style design that is more decorative than the Basic Heel Stitch.
Follow Steps 1 and 2 of the Heel Stitch to set up the knitting needles for the heel flap.
Insert the right needle into the first stitch on the second needle as if to knit. Slip it onto the right needle. Knit the next stitch. Note that this is the visible right side of the work.
Repeat Step 2 across the row of heel flap stitches. Turn the work.
Insert the right needle into the first stitch as if to purl, then slip it onto the right needle. Purl across to the end of the row.
Slip the first stitch as if to purl, then knit the next stitch.
Repeat Step 5 across the row to the last two stitches. Knit the last two stitches.
Insert the right needle into the first stitch as if to purl, then slip it onto the right needle. Purl across to the end of the row. Note that this is the wrong side of the work.
All wrong side rows of the Eye of Partridge are worked the same. It's only the right side rows that change.
Repeat Steps 2 to 7 until you have knit the desired number of heel flap rows. As with the Basic Heel Stitch, knit two-thirds to three-quarters as many rows as there are heel stitches.
Repeat Steps 7 to 10 of the Basic Heel Stitch to turn the heel of the sock.