How & Why to Knit Short-Row Bust Darts

If you have a larger bust, you might find that sometimes the front of your knitted top rides up compared to the back, or the back has extra baggy fabric if the front is the correct length. This is due to the extra vertical space that the fabric has to travel over your bust, as compared to the relatively straighter line traveling the same distance down your back. Short rows are a great technique to add length to just one area of a knitted garment, so they can be used to add that missing vertical length to the front of your bust. These are also called “horizontal bust darts”.

The short-row bust dart is highlighted in gray to show its shape and placement. The two black dots on either side show where a short row turn has been done.

(Illustrated example is based off of my Thine Own pattern, which includes both horizontal and vertical bust darts to create a custom fit).

a closer look at the shape of the horizontal bust dart

Staggering where you turn each short row will create a less visible dart line along the side of your garment; this staggered line is what creates the diagonal lines in the trapezoidal shape of the dart. If you were to turn at the same spot every row, creating a rectangular dart shape, the fabric would pucker noticeably as the sides of the dart wouldn’t lay smoothly against the shorter fabric around it.

Where to place the dart?

The ideal vertical placement for short row bust darts is at the fullest point of your bust. Generally, this is often about an inch below where the armholes of your top begin, but it may be higher or lower for your particular body. All of the short-row turns should take place in the distance between the center of your armpit, and ~1/2” outside of the “apex” of your breast (the fullest point of your breast - for many people this is where your nipple is, but it may be different). Placing the shortest turn slightly outside the apex of your breast helps avoid a visual dart lining up directly with your nipple, which might draw the eye.

Overview of the steps to calculate your own short row bust darts:

1. Decide how much length you need to add.

2. Calculate how many rows need to be added, to achieve that length.

3. Calculate how much space you have to work those short rows.

Step 1: How much length to add

There are a few ways to calculate this. The most accurate way to measure is by placing a measuring tape at the top of your shoulder, and measuring the vertical distance from your shoulder to the bottom of your bra band. Do this on both the front and back of your body, and subtract the difference of [front - back]. This will tell you how much extra vertical length your bust takes up.

Another way to more roughly estimate the difference is by looking at the difference between your full bust circumference and your underbust circumference (where your bra band lies). Bust - underbust - 4” = the amount of length to add (roughly). If you’ve ever measured yourself for a bra, you know that you determine cup sizes by comparing the bust to the underbust; you can also use your cup size as a proxy measurement for this as well, if you know your bra size is accurate. AA cup = 0” of short rows, A cup = 1”, B cup is 2”, etc.

For this example, I’ll use my measurements. Full bust = 34”, underbust = 29”. The difference is 5”. When I subtract 4” from this, I’m left with 1” of short rows recommended.

TIP: want to skip some of the math below? You can input your row gauge and the length you just decided above into this calculator to have it calculate for you.

Step 2: How many rows to add

Now you’ll convert the inches of length to rows of length, so you know how many short rows to add. You’ll need to use your rows-per-inch gauge to calculate this. If you’re working off a 4”x4” gauge swatch, make sure you divide your total row gauge by 4 to get your rows per inch.

Multiply your short row length times your rows-per-inch gauge to find the total number of rows needed. Example: 1” * 4.5 rows per inch = 4.5 rows.

Round this result to the nearest even number; you’ll work your short rows in pairs of 2, so they’ll always bring you back to the RS of the work. So I will round 4.5 down to 4.

Step 3: How often to turn

To figure out how often to evenly turn your rows (in order to get a smooth, staggered turn that is less visible in the fabric), you first need to know how many stitches are between the center of your armpit, and ~1/2” outside of your breast apex. All turns should happen between the center of the armpit and the bust apex, because you don’t want excess fabric bagging out between the breasts.

Put on your top, and place a stitch marker at the apex of each breast. For many people, this will be around your nipple, but all bodies are different. Adjust the two markers so they are placed evenly, and each have an equal number of stitches between the marker and the center of its closest armpit. Move each marker so they are ~1/2” outside of the apex (aka 1/2” closer to the armpit). Count how many stitches are between the marker and the center of the armpit closest to it. This is how many stitches you have to work with when making your turns on each side; we’ll call this “side stitches”.

(If you’re trying to generalize this without counting stitches, you can also divide the total bust stitches by 8; the apex of each breast is often about 1/4 of the way across the front of the chest on each side, so the distance between each bust apex and its closest armpit is about 1/8 of the total bust stitches. But this is just a rough approximation and won’t be true for all bodies.)

Now you can calculate how often to turn to evenly spread the short rows out. First, divide the total number of short rows by 2, since you’re doing half of the turns on each side of the bust:

Turns per side = [total short rows] ÷ 2

Now you can calculate how often you’ll turn on each side of the bust:

How often to turn = [side stitches] ÷ [turns per side]

Round this number down to the nearest whole number (since you can’t knit partial stitches!). This value will be called “Stitches Before Turn” below.

TIP: not confident with this math? You can use this calculator to do the calculations for you.

Putting it all together

Now that you know how many rows are needed and how often to turn, you’re ready to start working the short rows! Remember that you want to start them around the fullest point of your bust. This is often ~1” below the armpit depth. It doesn’t matter if you’re working them bottom-up or top-down.

To begin working the short rows:

For sweaters/tops (that aren’t cardigans):

Knit across the front of the top, passing the first bust marker, until you hit the second bust marker. Turn your work (using whatever short row technique you prefer), and purl back until you reach the first bust marker. Turn your work again. You’ve now completed your first 2 short rows! For the rest of the short rows, you’ll knit to the last place you turned, then knit an additional [Stitches Before Turn] stitches before you turn your work again. This spaces out the turns evenly, as we calculated above.

You can see the last place you turned by looking for the double stitch or the wrapped stitch that will be visible (depending on which short row technique you use).

For cardigans:

Since cardigans open in the front, you can’t knit continuously across the segment between the busts. Instead, you’ll need to work a short row dart on each side of the cardigan’s front separately. You’ll knit or purl from the neckline edge to the bust dart on the side you’re working on, then turn the work, knitting or purling back to the neckline edge (these are your first 2 short rows). On the next row, you’ll knit or purl to [Stitches before turn] stitches past the bust dart marker, turn your work, and knit or purl back to the neckline again (2 more short rows completed). You’ll continue this until you finish all your short rows, which is around when you’ll reach the center of the armpit on that side of the top. Continue knitting past the center of the armpit until you reach the neckline on the other side of the top, then repeat this process over again for the bust dart on the other front half.

What if you need more short rows, but you’re already turning every stitch?

If you need to add more short rows but you’re already turning every stitch, you can stack multiple bust darts on top of each other. You should never continue turning past the bust apex markers or the center armpit markers, since that will distort the shaping. Instead, you can begin over again with a second bust dart directly underneath the first one. Go through the same steps above to figure out how often you need to turn for your second dart, and begin the setup rows all over again.

What if you’re knitting bottom-up vs top-down?

You can use this same technique whether you’re knitting bottom-up or top-down! You can also choose to have your first turn be at the center of the armpit, rather than at the bust apexes, so the first full short row you knit will be the entire width from armpit to armpit. It doesn’t really make a difference if your “trapezoid” shape is oriented upright or bottom-up, as it will give you space for the bust regardless. I like to knit my first turns to just the width of the center bust apex because it allows you to add in vertical bust-darts below the bust as well, where you decrease below each bust apex, while still knitting short rows. My “Thine Own” pattern uses this technique.

What if you want to combine short row bust darts with vertical bust darts?

Vertical bust darts use decreases below the bust (or increases up to the full bust, if you’re working bottom-up) so there’s extra fabric at the bust that is removed at the underbust. If you want to combine short row bust darts and vertical bust darts, begin working the vertical bust darts after you’ve knit ~1” (2.5 cm) of the short rows. Work decreases at the bust markers when you pass them while working your short rows. You may finish working the short rows before you finish the bust decreases, which is fine.