Next you are going to see how to redraw a dart so that the pattern has a more curved shape at the underbust line. This can help you to redraw this area also in commercial patterns. Still remember that it is always good to make a prototype of problematic parts of a garment such as this area.
Before we begin, remember that this can be applied to any fitted body pattern. It is true that this type of dart is usually seen on strapless necklines (green line) but it can also be done on a standard fitted body (blue line).
Optionally, you can join the chest and waist darts to create a front side panel or princess seam (red line).
First measure the height from the nipple to the underbust line and mark it on the dart. Imagine you are wearing a bra, you should measure at the point where you have the underwire of the bra.
This is the point where the fitting should be done. There is no rule of how much you should fit, it will depend on your bust size so it is important to make a prototype.
You can see the difference between your chest circumference and your underbust circumference to more or less get an idea.
Imagine you want to fit 2 cm.
You can distribute 1 cm on each side of the dart or you can fit more on the side panel. It partly depends on the design. I like to fit more at the side panel than at the center front piece because it makes the seam appear visually straighter.
You can put 0.5 cm on one side and 1.50 cm on the other.
This is really just an example for your understanding.
To redraw the line you should use a curved ruler.
Something to keep in mind if you distribute the centimeters differently on both sides of the dart is that the side curved will probably be longer. You should measure both lines and adjust the length of the side piece with respect to the front center piece.
See you soon!