Recently I wrote about dart placement, once you know you are going to use darts the next question is, how much extra space do you need?
It's time to start thinking three dimensionally here. The paradigm used for knitting patterns is one dimensional, however a three dimensional garment is being created, it needs to be wrapped around the curves and various planes of the body.
There are a number of methods to determine how much extra room is needed for a full bust. The first is to mark the waist by tying a string around the waistline. Place a pin at the center of the shoulder seam line. On the back, measure from center of shoulder seam line at marker down to waistline. Measure the front in the same way following the curve of the bust. Compare the two measurements. The difference is the number of inches of extra fabric required.
The second method is to measure the body at the widest point of the bust. Measure the high chest next. Take that measurement with the tape up at the armpits and above the bust. Compare the two measurements, the difference in the number of inches determines how much more room is required.
The third method is to use an existing garment to help determine how many rows are required by examining how much the garment pulls up at the waist line. Calculate by multiplying the measurement by the row gauge. Use another sweater or stretchy garment as the baseline not a woven item.
The final method, is to use the bra cup size to determine the number of inches required. The chart below gives the differences by inch and cup size.
All of these methods give you a starting point, analyze each completed project, make good notes detailing area's of improvement and your next project will be even better.