Top-Down Design Tutorial 7: Figuring the Poncho Sweater Yoke

Stop the presses!

Remember how, a few posts ago, I said that all the sweaters I knit fall into three basic yoke designs: shoulder-down, round yoke, or raglan?

I lied. Sort of.

I also knit a lot of poncho sweaters, which started life as raglans rotated 90 degrees:

See the cool chevrons and the pointed hem? What's not to love about that? It's a fun, flattering design for most women.

I progressed to filling in the back neck with short rows to avoid a V that matches the front and save the wearer from shivery feelings down the back.

I knit so many of them that I wrote a program to do the math for me (and for other people who saw them and wanted to knit them as well).

Eventually adding details like running a cable down the front as an accent:

The Moths-in-the-Twilit-Forest Yarn originally beckoned me because it wanted to be the next version of Azteca. It promised to be the yarn that would prompt me to write Azteca up in various sizes and actually publish a pattern for it. So I bought it, and had some recycled cotton yarn in mind for the other stripes.

The yarn was pulling the old bait-and-switch, however. When I got it home and wound, it insisted that it really ought to be a poncho sweater. The recycled cotton would work great for the ribbing, and (here it dropped its voice to a seductive whisper) I could try running a cable down the front in a contrasting color. Meanwhile, I could refine my poncho sweater program and perhaps port it from perl to Python.

Okay, deal.

Here you can see the short rows filling the back neck:

And this shows the neckline and start of the cable:

Well, I'm having fun, so I must be doing it right!

The basic poncho sweater, which is merely a raglan rotated 90 degrees, is fairly simple to figure. The only tricky part is that the fabric mostly hangs on the bias, so you need to figure out the diagonal gauge of the fabric as well as its stitch and row gauges. You get the v-neck for free with the center front increases, but you have to figure your neck cast-on as the hypotenuse of a triangle with the back neck as one side of the triangle and the neck depth as the other side. (Moreover, as I was trying to explain that bit, I realize that I got it wrong in the program and will need to refine it. Ah. Knitting design and programming, strange are the offspring thereof.)

The math therefore starts out just a little tricky, but quickly gets more complicated. Adding the back neck short rows makes it a bit more difficult to figure. Moving the sleeve increases so that you get normal raglan sleeve shaping yields a better fit, but complicates the shaping a little. And my latest idea for a modification, not starting the arm and back increases until after the neck ribbing, complicates it still further.

But on we go.

The first thing to do is to knit an unusual gauge swatch.

The gauge swatch for a poncho sweater needs to have the same bias as the fabric. So cast on 40 stitches, place a marker in the middle, and knit so:

Odd rows: K1, k2 tog, k16, left make one, k2, right make one, k16, ssk, k1

Even rows: Purl.

This gauge swatch needs to be on the large side, about 8 inches long. Row gauge is measured along the center line, nice and simple. Diagonal gauge is measured straight across the piece, 40 stitches divided by whatever measurement you get across the piece. Stitch gauge is measured along a single half row from the edge of the piece to the center line.

For Moths-in-the-Twilit-Forest, I got a row gauge of 5.33 rows per inch, a stitch gauge of 4.5 stitches per inch, and a diagonal gauge of 5 stitches per inch.

The body of the sweater hangs on the bias and uses the diagonal gauge for all horizontal measurements. The sleeves hang straight and use the stitch gauge for all horizontal measurements. The row gauge is the same in both cases, and is used for all vertical measurements.

From the top, now.

The back neck is 5 inches, just like the standard measurement charts. Add an inch and a half for each sleeve. Figure the diagonal line across the front neck using the Pythagorean formula: (c² = a² + b²), where c is the diagonal line you will cast on, a is half the back neck, and b is the desired neck depth.

With a poncho sweater, you cast on a lot of neck stitches because you get the neck depth for free as part of the center increases. Way cool.

As soon as you start the sweater, you start the center front increases. Put a marker between the two center stitches, as you did with the gauge swatch, or run a panel up the center and increase on either side of it. (The panel also changes the math for the hypotenuse, naturally.)

Work the neck ribbing, on smaller needles naturally, including the center front raglan increases.

As soon as you finish the neck ribbing, you work the short rows to fill in the back neck. You need to fill the depth of the front neck, so you work as many rows as it takes to get that number of inches, working center back raglan increases as you go. When you finish the center back raglan increases, you should have the same number of stitches in the back as you have in the front. Since you haven't started the sleeve increases, yet, you have a little fudge room here.

If you have a stripe pattern for this sweater (and poncho sweaters almost demand one), you need to figure the short rows so the striping will come out right.

Okay, once the short rows are finished, you can start the real work of the sweater. Front and back raglan increases (at the center) have to happen every other row to keep the chevron line going. You're going to have a fixed number of these increases to the underarm. The sleeve raglan increases, however, can be adjusted. So you figure out how many stitches you need to make the fronts and backs come out right (remembering the underarm cast-ons). The rest of the stitches go into the sleeves.

You had a lot of extra stitches in the cast on to account for the neck, so the initial quantity of sleeve stitches is much larger than normal. You will thus need to do a lot fewer sleeve increases than normal. Figure out how many this is and space them evenly over the the yoke, again remembering to account for the underarm cast-on.

So you knit downwards to the point where you divide the arms from the body (cackle! I love that part! Feels so witchy!). Do the underarm cast-on as normal, and put markers on the sides. For the rest of the body, you will do decreases on either side of these lines to make up for the center increases that you're doing. This will keep the garment sweater-shaped rather than poncho-shaped.

For a diamond-edged poncho sweater, you continue straight downwards, doing double increases at the front and back centers and double decreases at the sides every other round. Bust short rows and general body shaping don't work so well with this design, so I suggest omitting them.

If you don't want a diamond-edged hem, you can fill in the sides using increasing short rows.

If you want to knit a poncho sweater, you don't have to do the math yourself.
Send me an email and I'll have my program do the math for you.