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  • Writer's pictureALittleBitSheepish

Fantastic fit - Vertical bust darts

This month I am sharing one of my favourite techniques for making garments fit - adding vertical bust darts.

Fitting sweaters to bust measurement, for garments designed for female presenting bodies, can often lead to issues with fit at shoulders and arms. The variation in bust measurement across makers can be 30 cm / 12" or more. Although a looser style may accommodate the difference, for fitted garments this needs to be considered.

A solution? To fit the garment to the upper chest/bust measurement - approximately at the underarm point, and increase the stitch count to suit the bust.

Increasing the stitch count can be achieved by working vertical bust darts. Starting at the upper chest point, lines of increases are worked (usually two but it depends on the pattern and the sizing) to reach the desired stitch count at the full bust point.

To get the best fit from your knitting you need to take some measurements and work out how many stitches to add and take away when the bust shaping is worked.


Upper bust- measured at the underarm point where the work is divided into sleeves and body. Use this to determine which size to make.

Full bust- measured at the largest point of your bust. Use this to work out how many stitches to add.

Depth between upper bust and full bust- measure from the underarm join to just above the fullest point of your bust. Use this to work out how much depth you have for your increases.

You will also need to know your gauge.


  • Add your preferred ease (if any) to any of the measurements before working the calculations. Bust darts work best with negative and small amounts of positive ease.

  • You might have to tweak the numbers up or down to get whole numbers of stitches, knitted fabric is quite forgiving of this.

  • Have someone else measure you to get accurate results.

Stitch calculations:

Example is worked in inches, but can also be done in cm.

Once you have your numbers there is a bit of maths to be done, we’ll do it step by step.

Increase needed = full bust – upper bust

Example = 42” – 38” = 4” extra fabric needed

Your increase = = .

Stitches to increase = Increase needed in inches x stitches per inch (from your gauge)

Example = 4” extra fabric x 5.5 stitches per inch = 22 extra stitches needed

Your stitches to increase = x = .

Decide how many bust darts you will be working; at least two- one on each side, but if you need to add quite a few stitches (more than about 20), or have a high full bust, work four- two on each side. Then calculate how many stitches to add at each dart.

Stitches to add at each dart = Extra stitches needed / number of bust darts

Example = 22 stitches / 4 darts = 6 stitches at each dart (rounded up for whole number)

Your stitches at each dart = / = .

Stitches are typically added at each dart every other row. Work out the number of rows for the increases.

Number of rows for increases = Stitches at each dart x 2 (because you increase every other row)

Example = 6 stitches x 2 = 12 rows

Your number of rows for increases = x 2 = .

Check the depth of your increases and compare it with the depth you have measured between upper bust and full bust.

Depth for increases = Number of rows for increases / Rows per inch (from your gauge)

Example = 12 rows / 7 rows per inch = 1 ¾” inches from underarm to full bust.

Your increase = / = .

Compare this with your measurement. The stitch count should reach the full bust measurement just above the full bust point.

If it is too short you could reduce the number of bust darts or increase every third row.

If it is too long you can add an extra pair of bust darts.

Where to put the increases:

Place stitch markers for the darts a quarter to a third of the way in from the side seams on each side. If you are placing a second line of increases on each side place them half way between the edge and the markers already placed.

You can tweak the placement to accommodate stitch patterns, for example cables.

Working the bust darts:

Work to marker in your established stitch pattern, work your preferred increase (I like a make one or a lifted increase); repeat this to the final marker then work to end of round/row. You can use paired increases if you wish.

Work a round/row with no increases.

Repeat this until you have reached your target stitch count for the bust/chest.

Working even:

Once the increases have been worked a section of 1-3” should be worked without shaping to avoid a pointy bust shape.

Bust decreases:

Decreases can be worked to pull the fabric in under the bust.

Typically patterns work a decrease every row at the markers used for bust increases until the required stitch count is reached.

If you would like to pull the fabric in more under the bust, continue working the decreases until you reach your desired stitch count.

If you would like a looser fit to the body you can work fewer, or no, decreases at this point.

Vertical darts can also be used to shape other areas of a garment - decreases at the sides for the waist or at the back to bring the fabric in where it naturally curves. Increase to add fabric for hips and bums.

If you are planning to add bust darts to a pattern you are designing you can find resources with upper bust/chest measurements in this blog post.

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