Bust cup adjustment on knit tops

Knit garments have the advantage of moulding easily on the body. This makes its fit is much easier than a garment made of non-stretch fabric. Nevertheless, a knit top made too small at the bust will not fit right and can deform the armholes or necklines. Our patterns are adjusted according to a B cup and we highly recommend that you adjust your patterns if you are a C or D cup. If you are unsure about your bust cup, click here to measure it.
 

To increase the bust cup on a bodice, the bust dart must be increased. Obviously, there are no darts in a knit top, therefore we must proceed in a slightly different manner. In the following technique, we will slash the pattern at key places and shift its pieces in order to raise the neckline and enlarge the front bust width. This technique can also be used on loose woven garments such as shirts.

Tools needed:

• The front panel of a knit top/dress
• A measuring tape
• A pencil
• A ruler
• Paper scissors
• An extra sheet of paper
• Pins
• Clear adhesive tape
• A seam gauge

Ensure that the seam lines are well indicated on the pattern. Let's get started...

1- With a measuring tape, run along the shoulder and front armhole seam lines and note their measurements. Note the position of any notches located on these seams as well.

2- With a pencil, trace a straight line, perpendicular to the centre, about 10cm (2") below and above the bust level. Trace another line, parallel to the centre, from the centre of the shoulder, all the way down to the first line, drawn below the bust level.

3- Take your scissors and slash the pattern along these lines, as shown below: across the line above the bust and the line going down the shoulder, all the way to the line below the bust. Then, make a 90° toward the side seam and cut across the remaining part of this line.

You'll end up with 4 pieces: one for the bottom part, one for the underarm, one for the neckline and one for the top part of the armhole.

The bottom and top armhole parts are going to be static while the underarm and neckline parts are going to be shifted.

4- Place the bottom part of the pattern on a sheet of paper, pin it to the sheet and trace two straight lines parallel to the previously cut edges (namely the line above the bust and the one parallel to the centre). The distance will depend on how much you wish to increase the cup and is calculated according to a 6mm (1/4") increment. As our patterns are based on a B cup, you should increase the pattern by 6mm (1/4") for a C cup, 12mm (1/2") for a D cup, and so on...

5- Take the remaining parts and pin them to the sheet, as shown below. Align the bottom edge of the neckline part with the parallel line, drawn horizontally. Ensure to straighten the centre front edges. Align the right edge of the underarm part with the parallel line, drawn vertically. Ensure to not leave any gaps below the bust. The last part is static - it must remain at its initial position - ensure to align it tightly with the other parts.

6- Apply some clear adhesive tape along the cut edges to stick the pattern to the sheet. Remove the pins.

7- Reshape the shoulder seam line by connecting the highest and lowest point together.

8- On the front armhole, mark the middle of the jump, where the parts are shifted, and ensure to pass by that point when reshaping.

8- Reshape the front armhole seam line.

9- Reshape the side seam line in the same manner.

10- Now it's time to use the measurements noted in the first step. Grab the measuring tape and run along the new seam lines to measure them. If you have increased by only one cup, chances are that these measurements remained the same. But in the opposite case, the "shoulder - armhole" point must be shifted, in order to match the initial measurements. Mark the initial measurements on the shoulder and armhole, starting from the neck and underarm. Then roughly square in from these markings. The new shoulder - armhole point will be at the meeting point of these lines.

If there was any notches on these seams, reposition them accordingly.

11- Using a seam gauge, reshape the seam allowances by tracing a parallel line along the shoulder, armhole and side seam lines.

12- Cut the excess of paper around the pattern and stick a scrap of paper below the side seam, if needed, to fill the new seam allowance.

Depending on how much you increased the cup, the front side seam might become slightly longer. It's like if a "mini dart" was created in the side seam, which is normal. Do not correct this and when sewing, ensure to stretch the back side seam in order to match the front, from the waist to the underarm.

As always, when you "butcher" a pattern, ensure to keep the amended piece if you ever decide to copy it! When cutting in the fabric, if you experience some difficulties to pin through the pattern, use small and heavy objects (Mugs, small jars...) to stabilize the pattern and chalk the fabric around its outlines. Then you can remove the pattern and cut along the chalk lines. 

This technique can also be used on loose woven fabrics but ensure to widen the panel all the way down. Such kind of garment has a straight side seam (parallel to the centre) so it must remain that way.

I hope you enjoyed this tutorial and if you have any question, do not hesitate to leave them in the comment section!