Fall is upon us, and so is the new issue of Interweave Knits Gifts! Included among the patterns are several gorgeous cowl patterns, perfect for the transition into colder weather. Cowls are a great little accessory to pair with your boots and tights for trouncing through fall leaves. They're also super customizable, making them a great project for making your own. All it takes is a little help from our good friend math.

Say you love the 31" Fairbanks Cowl in this issue of Gifts, but you'd prefer a longer, more dramatic, infinity scarf version. All it takes is a little basic math to figure out how to change it to your liking. When changing the length of any cowl, you need to determine how it's constructedin the round from bottom edge to top edge? Or worked in rows the long way and joined end to end? Here, we'll discuss how to change the circumference of a cowl worked in the round from bottom to top, as the Fairbanks Cowl is worked. Because this cowl is worked in long rounds, it is the stitch gauge and number of repeats that determines the circumference. Most cowls are designed with a set pattern repeat that divides exactly into the total stitch count, making cowls an easy project to alter stitch counts in—you just work with multiples of the stitch pattern repeat. So, we need to calculate the length of each repeat, which is shown on the chart.

Repeat length: 32 stitches.

Secondly, we need the stitch gauge. Row gauge isn't important, as it doesn't affect the length of your finished cowl (rather, it affects the height in this case).

Gauge: 16 stitches = 4", or to rephrase it, 4" per 16 stitches.

Then we do a little math to figure out how long the repeat is. To find that, you take the repeat length, multiply it times 4", and divide it by the stitch gauge.

Approximate repeat length: 32 stitches x 4"/16 stitches = 8"

Another way to look at it: the gauge is 4 stitches to 1", so 32/4 = 8"

In this case, we're lucky that the repeat length is a tidy whole number; typically it's going to be something funky with a decimal place or two. What this number tells us is that our cowl length has to be a multiple of 8". Longer, infinity-style cowls are usually 60-70" around, so let's make our cowl 64" around.

64" circumference x 1 repeat/8" = 8 repeats.

From here, we just multiply the number of repeats (8) times the number of stitches per repeat (32).

8 repeats x 32 stitches/1 repeat = 256 stitches.

This is the number of stitches you need to cast on for a 64" Fairbanks Cowl. Easy! Just don't forget that if you decide to make your cowl longer, you will need more yarn.

Making a cowl smaller is the exact same process. Say you love the generous 67.5" Radcliffe Cowl, but have little ones who would love to wrap their grubby little fingers in it, so you'd prefer it sat a little more snugly against your neck. Let's go through the process again:

Repeat length: 16 stitches.

Gauge: 19 stitches = 4".

Approximate repeat length: 16 stitches x 4"/19 stitches = about 3.4"

Or, since the gauge breaks down to 4.75 stitches to 1", 16/4.75 = 3.4"

Uh-oh, 3.4" is not the easiest number to work with. However, it's still simple to convert. First, let's decide about what circumference you'd like your cowl to be. Neck-hugging cowls are typically 20-30" in circumference, depending on how tight you like them. Let's go with 25", in the middle of the range. Divide your ideal circumference by the repeat length.

25"/3.4" = 7.35

Then, because we need a whole number to work the chart, round it. In this case, we'll round up; it's better to have a slightly bigger cowl than one that doesn't go over your head! We'll use 8 chart repeats.

8 repeats x 16 stitches/1 repeat = 128 stitches.

Again, this is the number of stitches you need to cast on. You can also use this number to figure out the actual circumference of your finished cowl. Multiply your cast-on number by the gauge.

128 stitches x 4"/19 stitches = about 27"

It's a little bigger than we were aiming for, but still wearable and the perfect length for tucking under a jacket collar.

Using these basic formulas, you can adjust the length of any cowl to suit you. Pick up a copy of Knits Giftsspend some time with math, and make any cowl your own.