Toe Up Knee Socks Step 2: Taking Some Measurements

Warning! Here comes a little bit of knitty math. But I promise, it's not hard. Grab some soothing tea, a tape measure, a convenient leg, relax and just follow the instructions and everything will turn out fine.

Leg Schematic

Apologies for the image... it was the best leg image I could find in my MS clip art collection and I didn't want to steal anyone's images off the web. So you get hiker guy leg. I'll try to do my best to describe what you're measuring and why. I recommend that you take these measurements while sitting down, your foot flat on the floor and your knee at close to a 90 degree angle.

Before you get started, make sure you measure the number of stitches per inch and the number of rows per inch (or whatever your favorite unit of measurment is) for the instep of your sock. You'll need this number later.

Circumference Measurements

A: Ball of the Foot. This is not really a required measurement, but it's the measurement that determined the circumference of the instep of your sock. Generally speaking, it's going to be one of the widest parts of your foot. Most of the time, if you take this measurement and multiply it by 0.9 you're going to have the circumference of your sock. The reason you don't use 100% of the measurement is that knitted fabric stretches, and a good sock has a little grip to help keep its shape.

B: The Leg, Just Above the Ankle. You need to take this measurement. Usually this measurement around your leg just above the ankle is going to be very similar to the circumference of the ball of your foot -- this is why most sock patterns have the same number of stitches for the leg and instep of a sock. This measurement is important for us, because it represents the narrowest part of your leg (in most cases) and it's going to determine the base number of stitches around the leg before we start any shaping.

C: The Calf. I know, I know, this is not something a lot of us want to measure. But if you're going to have a well fit knee sock, it's a pretty critical measurement. Be sure you're being honest when you do the measurement and that you get the circumference of your calf at the widest point. This measurement is going to determine the number of stitches we're going to increase to as we do any shaping.

D: Just Below the Knee. This is the place where you want the sock of the top to hit. Because the circumference of this area is usually a bit smaller than the widest part of the calf, it's important to measure this area too, otherwise, you may end up with a sock that is too loose at the top, even with ribbing. Nothing sucks more than a knee sock that is always falling down.

See? Not so bad so far, right? Okay, now let's take the length measurements,

Length Measurements

I'll be the first to tell you that taking some of these measurements can be a little fussy. Sometimes, it can help to have someone who can help you with these. If you can't find good help like that, just be patient and careful. It works. I had to do it for my own sock measurments.

E: From Knee to Floor. You want to take this measurement at the back of your leg, from the floor to just under your knee (or wherever you would like to have the top of your sock hit). You don't need to worry too much about curvature -- since the front part of your leg is pretty much straight down, it balances out in the end.

F: From the Widest Part of the Calf to the Floor. This is one of the most important measurements you will make, since it's going to help determine where the increase shaping for the calf stops and the decrease shaping for the knee starts. When you measure your calf circumference, you might want to make a little mark on your leg to help you remember where you are measuring to. Rubber bands that won't cut off your circulation work well for this sort of thing if they'll stay put.

G: From the Area Above the Ankle to the Floor. This is another location you might want to mark after you measure the circumference. It's also an important measurement.

Ok. Take a deep breath. All the measuring is done. Now there's just a little bit of math ahead. But don't worry. You can do most of it without even resorting to a calculator, and I'm going to show you an example, based on my own measurements.

A. 8.5"
B. 9.5" (note, I did this a little higher than just above my ankle, which is why it is longer than A)
C. 13"
D. 12"
E. 15"
F. 12"
G. 8"

Stitch Gauge: 7 stitches/inch
Row Gauge: 11 stitches/inch

First of all, let's start by determining how many stitches around you're going to need for that widest calf measurement. We need to calculate for some stretchiness in the fabric, so first off we're going to only use 90% of the circumference measurement for the calf. Then we're going to multiply that number by the number of stitches per inch in our gauge.

Calf Circumference Stitches: C * 0.90 * Stitch Gauge
Ex. 13 inches * 0.9 * 7 stitches/inch = 82 stitches Calf Circumference

Now we're going to figure out the number of stitches we should be starting from just above the ankle. The formula is almost exactly the same:

Ankle Circumference Stitches = B * 0.90 * Stitch Gauge
Ex. 9.5 inches * 0.90 * 7 stitches/inch = 60 stitches Ankle Circumference

So far so good, I hope!

Since I like to keep my numbers divisible by 4 (to be compatible with dividing over 4 DP needles and dealing with K2P2 ribbing at the top) I am going to round the number of stitches for the calf circumference down to 80. You can choose to do this of thing or not. It's up to you. Generally speaking, a few stitches either way won't make too much difference unless you are using a very large yarn for your sock. To get the total number of stitches your're going to increase:

Increase Stitches = Calf Circ Stitches - Ankle Circ Stitches
Ex. 80 stitches - 60 stitches = 20 sitches increased

Now you need to decide how many increases you want to make on a row every time you do an increase row. Once again, I like to add a number of stitches that keeps my total number of stitches on the needles divisible by 4. So I chose to increase 4 stitches every increase row. To get the number of increase rows you're going to need to have:

Increase Rows = Increase Stitches / Stitches Increased Per Row
Ex. 20 stitches / 4 stitches/increase row = 5 increase rows

Okay. Now onto calculating the increases. First of all you need to calculate the number of rows in the length of the region that you are going to do your increases over.

Rows to Increase Over = ( F - G ) * Row Gauge
Example: (12 inches - 8 inches) * 11 rows/inch = 44 rows to increase over

Now you determine the increase row interval.

Increase Row Interval = Rows to Increase Over / Increase Rows
Ex. 44 rows to increase over / 5 increase rows = 8.8 rows

It's hard to do increases every 8.8 rows -- at least I haven't figured out how to knit 8/10ths of a row yet. So I decided to do my increases every 8 rows, starting at 8" above my ankle. Rounding up or down is a personal thing, but I wanted to make sure I still had room to do the decreases after the calf, so I chose to round down a bit. (That meant that I would have all my increases completed in 40 rows (5 increase rows * an increase row every 8 rows = 40 rows), so I knit four rows even after that before dealing with the decreases).

I hope everyone is still with me. We're getting close to the end. The last thing we need to do is figure out how many stitches to decrease to snug up things around the area below the knee.

Below Knee Stitch Circumference = D * 0.90 * Stitch Gauge
Ex. 12 inches * 0.9 * 7 stitches/inch = 76 stitches.

This is a nice number, because it's already divisible by 4, if you want K2P2 ribbing you'll want to adjust your number up or down to a number divisible by 4. In this case, I usually go the direction that leads to the fewest stitches added or subtracted. Now to calculate the number of stitches we have to decrease.

Number of Stitches to Decrease = Calf Circ. Stitches - Below Knee Circ. Stitches
Ex. 80 Calf Stitches - 76 Below Knee Stitches = 4 stitches.

Just like I increased 4 stitches/row for my increase rows, I'm going to decrease 4 stitches on any decrease row.

Decrease Rows = Decrease Stitches / Stitches Decreased Per Row
Ex. 4 Decrease Stitches / 4 Stitches Decreased Per Decrease Row = 1 Decrease Row

Usually, I want to do all my decreases before I start the ribbing. So now you need to know how many inches of ribbing you're going to knit. I did an inch of ribbing.

Rows to Decrease Over = (E - F - Inches of Ribbing) * Row Gauge
Ex. (15 - 12 - 1) * 11 = 22 Rows

Decrease Row Interval = Rows to Decrease Over / Decrease Rows
Ex. 22 rows / 1 decrease row = 22 rows.

Now, this result isn't entirely helpful because it doesn't really tell you where to place anything. In this case, I could place it at the very first row after I'd completed my increase intervals. But I decided that to better match the shaping of my leg, I'd do it halfway through the number of rows to the ribbing. So I did my decrease row 11 rows after completing the 44 rows over which I did my increases. After that, I just knit 10 more rows straight and started in on my ribbing.

See? Not so hard. A few calculations and you've got yourself a simple stockinette knee sock.

But what if you want to include a simple pattern motif? How do you know where to put those increases and decreases? That takes a bit more math and a little bit of thought, so I figured it would be best to split it into it's own section. Stay tuned for the last part of this tech discussion...