What Even Is It?

Sweaters designed with a raglan sleeve can be identified by the uninterrupted diagonal “seam” — which is often not a real seam but rather a line of increases or decreases that creates the appearance of a seam — stretching from the underarm to the collarbone.

Unlike many sweaters, raglans have no shoulder seam. Instead, the top of the sleeve becomes the shoulder of the sweater. This means the “shoulder” of a raglan sweater is fairly loosely defined, and fairly relaxed and easy to wear.

Since it allows for greater freedom of movement than set-in-sleeve or drop-shoulder construction, raglan construction is often used to make sportswear. The “baseball T-shirt,” with three-quarter-length colored sleeves and a gray or black body, is probably the most famous raglan style, but a lot of sportswear is made with raglan construction because the sleeve and shoulder construction allows for easy movement. If you start looking for them, you’ll notice them everywhere — in winter coats, cozy sweatshirts, exercise clothes, and a huge number of contemporary sweater patterns.

How Raglan Is Accomplished

The most common way that knitters construct raglan sweaters these days is in one piece from the top down. In these patterns, the first row contains foundation stitches for the entire sweater: back, front (in two pieces), and two sleeves. But the foundation row consists primarily of stitches for the back neck, with just a handful of stitches cast on for the very top of the raglan sleeves and even fewer (often just one stitch) for each side of the front.

The first row also often includes four “seam” stitches that are marked so the knitter knows where to place the raglan increases.

In order to create some depth for the neckline on the front, the sweater is knit back and forth for at least a few inches; after a few inches, the two fronts will be joined. The knitter increases on both sides of every seam stitch on right-side rows until the front neckline depth is reached, and the two sides of the front are joined together. Then the knitter carries on, working now in the round, until the sweater reaches the desired length to the underarm.

All of the parts of the sweater grow on a diagonal away from the cast-on row, so that the sweater gets wider and the stitch count increases on every right-side row.

If the sweater were continued in this manner for thirty inches or so, it would become a poncho. 

Instead, when the knitter reaches the underarm, both sets of sleeve stitches are taken off the needle and put on waste yarn, and the front and back are joined together at the armpit with a set of new cast-on underarm stitches added in between them. These new stitches create ease of movement at the underarm.

The body is then knit downward until the desired length is achieved. It might be widened, for a kimono-style shape; it may be knit straight down, for a standard pullover silhouette; or it may be narrowed with waist shaping. Length options range from cropped just beneath the underarm to thigh or dress/robe length or anything in between.

Here’s a summary. Note, though, that the picture shows the body and sleeves flat, but in reality they are tubes.

Limitations of a Constant Rate of Increase

In the most straightforward possible raglan design, the knitter increases one stitch on each side of every seam on every right-side row to the underarm. This means that the front grows by two stitches on every right-side row, the back grows by two stitches on every right-side row, and each sleeve grows by two stitches on every right-side row.

In this approach, with the rate of increase held constant on all pieces of the sweater, the ultimate width of the front, back, and sleeves at the underarm — usually their widest point — is determined by (a) how many stitches were cast on in the first row and (b) how many rows the knitter completed to reach the underarm. That is, if you need a wider front, back, or sleeve, in this method the only way to get it is to either start with more stitches or knit a deeper armhole.

You can see in the illustration to the right what this means for sizing. The first, straight-size L pullover, has an armhole depth of 9 inches. To achieve a wider body for a 1X sweater, the second pullover, with the same rate of increase, has an armhole depth of 11 inches. And for a 3X sweater, the third pullover, with the same rate of increase, has an armhole depth of 13 inches.

Note, too, that the arms grow in circumference along with the armholes, so that the largest sweater has proportionally larger arms.

To avoid having such deep armholes while maintaining the same rate of increase, another option would be to cast on more stitches in the foundation row — which would create a wider neck opening.

The problem, though, is that someone with a larger body does not necessarily have a larger neck, larger arms, larger shoulders, or a longer distance from neck to underarm than someone with a smaller body. All bodies are different. The constant rate of increase found in “classic” raglan sweater accommodates only a limited range of difference.

Changing the Raglan Increase Rate

Luckily, there is no rule that says raglan increases must happen at the rate of one stitch on each side of every seam on every right-side row. The rate of increase can be different for every part of the sweater: sleeves may be increased every fourth row, for instance, while the back and front are increased every other row. Moreover, the rate of increase can speed up or slow down for every part of the sweater: the fronts can start out increasing every fourth row and then, when they get closer to the fullest part of the chest, can be increased every other row, or can increase two or more stitches every time.

You can probably imagine that these approaches will affect the shape of the raglan line. It won’t proceed at a precise 45-degree angle from underarm to collarbone if one piece of the sweater is growing at a different rate than its neighbor. Due to the stretch and malleability of knits, however, the difference is not always as visually apparent as you might expect.

Bodies that are infrequently accommodated well by off-the-rack clothing are unlikely to be accommodated well by standard raglan shaping. A customized approach to the rate of raglan increasing requires additional planning and math, but it also produces better fitting sweaters. It’s worth taking the time to figure out your desired measurements and work through the planning in order to get the garment you want — which is where I’ll pick up next time.