Raindrop Socks Part 2: The Heel Flap

This article is part of our All About Socks series. To knit along, use the Raindrop sock calculator to generate a custom pattern based on your own gauge and foot measurements and follow along with this guide for more detailed instruction.

At this point, the leg and cuff of the sock form a tube. It's time to add some shape to this structure so it will fit comfortably around our foot!

While there are a wide variety of styles of sock heels out there, my absolute favourite starts with a flap heel.  I prefer it to other styles because it is very easy to adjust, very easy to knit, and (when you get distracted) quite easy to put down and pick back up again without getting too lost in figuring out what happens next. 

The Heel Flap Explained

Why do we need to knit a heel flap?: Essentially, the purpose of the heel flap is to give extra "space", so that the sock can comfortably fit around the widest part of your foot.  When you are done knitting the cuff and leg of your sock, roughly half of the stitches from the leg get set aside, either on a spare needle or a stitch holder, and the remaining stitches are worked flat (back and forth) into what looks like a little square or rectangular flap coming down off the tube.

You may have noted that in the above paragraph, I added emphasis to roughly half.  This is because, like most things in sock knitting, there is a bit of flex to this number. If adding or subtracting a stitch from the heel flap makes it easier to centre or fit a pattern repeat on the instep, or in any way gives you peace of mind or makes your life easier, then do so without hesitation.

Even vs. Odd: I have found that most modern sock patterns I come across use an even number of stitches for the heel flap, however, if you go back to the 19th century and earlier, most patterns use (and even explicitly recommend) an odd number for the flap. I find it's easier to centre most patterns I use over an odd number rather than an even, so by default, it's the count I use and recommend.

Place the previous __ stitches knit on a holder. Work the next steps over the remaining __ stitches.

The heel flap is a part of the sock that gets a lot of wear, so when knitting a pair of socks, this is a part that we want to make extra tough.  The sock flap that I prefer to knit is called a reinforced heel flap.  This fabric is denser, less flexible, and much sturdier against the wear and tear of going in and out of shoes.

A slip stitch heel flap, right side view.

In terms of how long to make the heel flap, the answer will depend a bit on the foot that is intended to wear the sock.  As a general rule, if I don't know who I'm making the sock for, I will knit until the heel flap is just a little past square, and write down how many repeats that took for the second sock.  If I'm able to take a heel length measurement and plug it into the calculator, however, that will fit better, especially for people with higher insteps or flatter feet.

The basic method is to work one row plain, and one row with alternate stitches slipped.  In more modern knitting terms:

Row 1: Knit __ stitches.
Row 2: * Slip one as if to purl, purl one, repeat from * until one stitch remains, slip one as if to purl.
Repeat the above two rows __ more times, for __ repeats total or __ rows

One of the nice things about this style of heel flap is that it is quite simple to count how many repeats have been done simply by running a needle through a column of the slipped stitches: 1 slipped stitch represents 1 finished repeat:

1 slipped stitch = 2 rows or one heel flap repeat.

There are other styles of heel flap out there to discover, but this one is effective, easy to remember, and simple to double-check, so it's the one I recommend starting out with when you're learning socks.

If your heel flap looks like this, you're doing it right!

When you have completed the required number of repeats, turn so that the right side is facing, and it's time to start the heel turn...

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