Raglan shaping formulas
Updated: Mar 17
One question shows up again and again: What formula do you use to shape a raglan? This one’s for designers and knitters - let’s talk about what makes a raglan click!
Fundamentally, a raglan is a sweater that is shaped between the underarm and the neck with four columns of decreases that go from the front and back of each armhole up to the neck. That area - the underarm to the neck - is called the yoke.
Common misconception: all raglans increase in the front and body every other row and are seamless. Neither of these is carved in stone, and as you'll read below, it's rare that all sizes will require the same shaping rates
To create a raglan, a designer will determine the desired yoke depth, shoulder width (stitches at the neck), neck width, bust circumference, and bicep circumference. Everything after that is finessing.
Yoke depth is determined by the body's dimensions
For a raglan to fit well, the yoke has to be deep enough for the rise of your shoulder (our shoulders are not flat lines across, but rise from the tip of the shoulder to the inside point of the neck), your armhole, and some wearing ease (usually about 1”).
In contrast to yoke depth, which is the total depth of the top part of the sweater, raglan depth is simply the rows you work from the cast-on to the underarm. It’s a vertical measurement and you just apply your row gauge to the number of rows worked.
Don't forget the shoulder stitches
To get from raglan depth to yoke depth, you need to add in one-half of the shoulder stitches. Those stitches sit right across the top of the neck, and contribute to front and back neck depth. Half of the shoulder width + raglan depth = yoke depth.
Check out the illustration. On the right-hand side, you can see the bracket enclosing the whole yoke depth, which is made up of the raglan depth and half of the shoulder width.
On the left side, in red, there are two arrows showing raglan length. This is a diagonal measurement and is more or less useless for predicting your fit because you won't know where it begins or ends in relation to your neck or your underarm
Shaping the yoke
So if you’re a designer, you’ve got a stitch count at the sleeve and a stitch count in the front and back. You also have a stitch count in the shoulder and neck. That will tell you how your stitch counts change as you move from the underarm to the neck.
If you’re used to knitting a shaping row every other row from the neck to the body, it can be a surprise to learn that’s not always going to work. Knitters in small sizes usually need to make more increases for the sleeve than the body, and have to work fewer increases per row.
Knitters in larger sizes will often need to increase every row, and will need to add more body stitches than sleeve stitches.
By determining desired stitch and row counts, and then determining the number of increases to make, you arrive at a sweater that fits perfectly.
Raglan shaping needs to mirror the body's shape
Here’s the thing - if you’re used to working the same shaping all the way from the neck to the underarm, you may have noticed that creates a very straight line, and fundamentally is making a rectangular pyramid. We aren’t shaped like that!
Right after the bust, we decrease dramatically in circumference, then we don’t change very much in the mid chest, and then our circumference narrows rapidly from the shoulder to the chest.
The shaping for your raglan will fit best if you mirror this “S” shape - also called “compound shaping.” Work decreases more closely at the top and bottom, and less frequently in the middle of the raglan line.
Check the illustration below. We change narrow dramatically from the full bust to the mid-chest, more slowly through the mid-chest, and fast again as we approach the neck. The arm follows the same pattern, although to a less extreme degree.
Bonus tip: Our bust line isn’t at the underarm. We don’t reach our widest measurement until several inches below the underarm (and the larger you are, the truer that tends to be!). If you’d like your raglan to be more body-shaped, make some of those body increases in the front only, and AFTER you’ve joined for the underarm. If you’d like to see this in action, check out Soft Structure.
Raglan neck shaping
As noted above, the shoulder width creates some space for the neck - equal space in the front and back. As long as that shoulder is around 2” wide, you should have adequate room in the back neck without adding extra shaping.
This is Linda, wearing Soft Structure, which has a shallow V-neck, and more increases in the front than the back - worked beneath the underarm.
When to add back neck shaping
If there are just a few stitches at the shoulder, consider adding shaping for the back neck in addition to the shaping for the front neck. Without this shaping, the collar will be pulled to the back. If the front neckline is shallow (like a crew neck), it may be pulled up into your neck. If the front neckline is deep (like a scoop or v-neck), the whole sweater may slide down the back.
What about front neck shaping?
It’s very rare that a raglan won’t need front neck shaping - the shoulder width needs to be about six inches wide for that to work. Sometimes, then, we’ll see necklines that work well in the middle and larger sizes, but because the shoulder gets more narrow as sizes get smaller, the smallest sizes don’t have adequate depth.
Overall, consider how much neck depth the shoulder shaping is contributing, and evaluate how much additional depth neckline shaping adds.
Want to go deeper on front neck shaping? Start here!
"Raising the back neck too quickly," and other short row shaping myths
The front neck can be shaped with short rows or by binding off in the middle and working decreases on either side. The short rows may be worked all around the neckline, or just back and forth so that stitches are unworked in the front neck only.
Myth 1: Short rows in raglans can be worked across the back neck only
If you've seen a pattern that has short rows that are worked just between the raglan columns in the back, you probably want to skip those rows.
I'm going to be extremely direct here, and if you think I'm wrong - write back and tell me.
As near as I can tell, that's happening because the designer has heard that they need to add short rows to the back but they don't really understand why or how. If you're a designer and you're doing this and you want to help me understand what your goal was, please do write back!
Working short rows right across the back of the neck will create a little tiny bubble in the back of the neck, just like a bust dart. It's knitting a little pocket for a nonexistent neck boob.
Note - if you have a hump on your back you can solve that with short rows - but they'll extend past the raglan lines so that they don't create that sharp little bubble. Those bust darts should extend part way into the sleeves. You'll want to add no more than about 5/8" right beneath the collar, and if you need to make up extra length you can work some short rows in the middle of the back too. But you wouldn't solve this by working right back and forth across between the back raglans.
Myth 2: Short rows in the neckline can ‘raise the back neck too fast’
Remember - what we're doing with short rows is leaving some stitches in the front unworked. These short rows work the exact same way that binding off in the middle and decreasing on either side works.
You can work those short rows right up against each other the same way you can work one decrease every row when you bind off. In the picture to the left, the top swatch is worked with short rows and the bottom is worked with bind-offs, but the shaping is the exact same. They look a little different at the top because of the final bind-off, but that difference disappears when you work in the round. Neither will cause bunching or will change the shape of the sweater in any way.
If you notice a garment has a ‘funnel’ shape, that’s coming from the shaping rate in the raglan (or if working a round yoke, in the yoke chart). You can get that same weird built-up neckline look from a sweater with or without short rows or neck shaping.
Modifying a raglan sweater to fit you perfectly
So what can you do with all this info? You can definitely think critically about the instructions you encounter in patterns you follow or you could use it to write your own knitting pattern.
But you can also use this information to modify a pattern you're working from. By understanding what the designer had in mind and what YOU need, you can intervene in an informed way.
Add a few stitches to your bicep to give yourself some extra room. To counter them, add a few extra decreases in the yoke. If the pattern has you decrease evenly between the bicep and the neck, add your new decreases at the top and bottom. If the pattern already has them distributed in compound shaping, add your new decreases evenly
Have a full bust and tum? Add a few extra raglan increases after you've split for the arms and body. You can add an inch or two here easily, and the whole sweater will be wider in the front only.
Working a smaller size and realize the yoke is too shallow? Add a few rows to the yoke to make it deeper, or decrease fewer times in the sleeve to make the shoulders wider.
I hope that these examples get you started thinking about how much control you have over your raglan knitting projects :)