A Guide to Bust Darts

While I wish I could create a blog post that was personalized to each individual body, that’s as unrealistic as designers being able to create patterns that will work without alterations for every body. My intentions with this are to get the basics of bust darts out there, where you can adjust them to fit your individual needs. Just like you might have to knit ten pairs of socks before you figure out your perfect fit, you might have to knit bust darts ten times before you get the fit just right – but don’t let that stop you! Figuring out how to knit bust darts has been a game changer for the fit of my sweaters, and the more you knit them, the easier they become.

This also looks like a ton of information, and that can be overwhelming, but the actual math involved only takes a few minutes, I promise.

This post will cover vertical bust darts. I prefer these over short row bust darts, like a lot. There’s less math, they require way less thinking in the actual knitting, and I think they look quite attractive. That being said, it’s my opinion that vertical darts are better for fitted garments. If you’re wanting to keep the front of a boxy sweater from riding up, then short rows are a better option. I’ll be covering short rows in another blog post, coming to a screen near you soonish.

Before I dive into the meat and potatoes of this crash course to knitted bust darts, let’s hit the FAQS.

What is a bust dart?

A dart is used to create a more fitted silhouette in garments by adding ease where it is needed, and taking in ease where it isn’t needed. The bust is the most common area darts are used; often (but not always!) more fabric is needed for the bust than the underbust and waist.

How do I know if I need bust darts?

If you have a large bust compared to your waist, you probably need bust darts. The easiest way to tell is to look at your garments, knitted or otherwise. Does the front sit higher than the back? Is the garment tight at the bust but loose or baggy at the waist? If the answer is yes, you might want to try bust darts.

Basic Measurements

Bust out your measuring tapes, and let’s get your basic measurements taken! You’ll need your full bust measurement, taken while wearing a well fitting bra at the widest point. You’ll also need your waist measurement.

You could use your underbust measurement, which is what I’ve always seen suggested in how-to’s. However, because I’m writing this specifically for fat people, I’d suggest using your waist measurement. Using my own body as an example: I have ginormous, low hanging boobs. My nipples hang about 6″ below where my underbust measurement is taken, and stop about 1″ above my waistline. If I decreased from my full bust measurement of 51″ to my underbust measurement of 40″, then I’d have 6″ of negative ease at my waist, and little space to increase for that.

You’ll need the measurement from the side seam of a thin t-shirt to your bust point (your nipples).

You’ll need the measurement from your bust point to your waist. To take this measurement, loosely tie some yarn/string/elastic around your natural waist, and measure from your nipple to that yarn/string/elastic, following the contours of your bust.

Don’t forget to have your gauge handy, as well!

Let’s do this!

Because the most popular method of knitting sweaters at the moment seems to be top-down and in the round, and because that’s where most of my experience lies, I will be explaining everything from that construction. However, you can definitely apply the same formula to bottom up sweaters, you’d just be increasing rather than decreasing, and you’ll have to know the measurement from where the hem of the top ends to your waist.

Take your full bust measurement and subtract your waist measurement from it. This number is the total amount you need to decrease. (Full bust – waist = decrease amount)

Using my own measurements as an example, my personal formula would be 51″ – 46″ = 5″.

To take this number and translate it into stitches, you’ll need your gauge, broken down into sts/inch. Multiply your decrease amount by your sts/inch, et voila, you have the total number of stitches you need to decrease. (Decrease amount x sts/inch = total sts decreased)

Again using my measurements with a gauge of 6 sts/inch, that formula would be 5 x 6 = 30 stitches.

I wish I could give you a magic measurement for where to start your decreases, like so many how to’s do, but let’s face it: everyone’s full bust hits at a different point, and every sweater’s sleeve separation hits at a different point. The easiest way to know when you need to begin decreasing is by trying your garment on. Some people will need to start 1″ after sleeve separation, some people will need to start 4″ after sleeve separation. This part will take trial and error, but after a few sweaters you’ll know when you need to start those decreases without trying it on every inch. You can also measure from your shoulder seam to your bust point, and use that measurement as a guideline for when to start decreasing.

So, now we know how many stitches we need to decrease, but how many rows should this take place over? You’ll need to know your rows/inch gauge, and the measurement from your bust point to your waist, which I’ll be calling “bust height”. Multiply your bust height by your rows/inch gauge. This is how many rows you’ll be working your decreases over. (Bust height x rows/inch = total rows)

Using my measurements, this formula would be 4 x 7 = 28.

We know how many stitches to decrease, we know how many rows to work these decreases over, how often do we work the decrease row? If you are decreasing 4 sts per decrease row, as I will be outlining, you’ll need to divide your total sts decreased by 4, which will give you the total decrease rows. (Total sts decreased / 4 = total decrease rows)

Using my measurements, this would be 30 / 4 = 7.5. Because I have a partial number, I’d omit the decreases at the side seam for my first decrease row, and use 7 for my total decrease rows.

Pull out your total rows, and divide by your total decrease rows to get your decrease row spacing. (Total rows / total decrease rows = decrease row spacing)

Using my measurements, this formula would be 28 / 7 = 4. I would work a decrease row every fourth row.

Now, where do these darts go? I typically decrease 4 sts on each decrease row – two at the side seams – which you should mark with a stitch marker – and 2 about .5″ or so from my full bust points (aka my nipples). You can do more math here if you’re a glutton for punishment (and I’ll include that formula in a moment) but what I do is try the sweater on once I’ve reached the point I need to start decreasing, pick a nipple, and pop a stitch marker right where my nipple hits. Using your sts/inch gauge, count half that number towards the side seam, and move your stitch marker there. (Using the sample gauge of 6 sts/inch, that would be 3 sts) I then count the stitches between that marker and my side seam, and add another marker to the corresponding spot on the other side.

For those of you who are much more precise, or who would rather do extra math than try on, you can use the measurement you took earlier from the side seam to your bust point to figure the total side stitches. Multiply this measurement by your sts/inch gauge. (Bust point x sts/inch = total side stitches) Then take your total side stitches and subtract .5″ worth of stitches from that, and there you go. You should have the number of stitches between where your dart will be and the side seam.

Now you have all of the math done! You know how many decrease rows you need to work, how to space them, and the placement of the darts! Hooray! No more math! (Have I mentioned that I greatly dislike math? Because I do.)

Onto the knitting!

Starting at your right side seam, k1, k2tog.

Work until three stitches before your dart marker, ssk, k1, slip marker.

Work until you next dart marker, slip marker, k1, k2tog.

Work until 3 stitches before your left side seam marker, ssk, k1, slip marker.

Work this decrease row at the rate you calculated earlier, and there you have it! Vertical bust darts.

I know the amount of math can be intimidating, but the actual math only takes a few minutes, and the finished fit is well worth it.

If you have questions, please feel free to reach out to me on Instagram @masteryarnsmith! Messages there are more likely to be seen than anywhere, so that’s the place to reach me.

2 thoughts on “A Guide to Bust Darts

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