Mainly depends on sweater style and people's posture. Simply divided into three categories:

1, knitting a small slim sweater, which requires 6-6.5 inches from top to bottom;

2, weaving a long slim sweater, weaving from top to bottom needs to be woven about 7 inches;

3. If you are knitting a loose sweater, or you are fat, you need to lengthen 1- 1.5 inches from top to bottom.

The knitting size of the back piece of the jacket is calculated as follows

1, starting from the bottom =( 1/2 bust-1 cm) × transverse density+sewing loss (needle)

2. Line length = (length-bottom rib) × linear density

3, the number of long body lines = (body length-bottom bar-hanging shoulder) × straight density

4. The number of stitches in shoulder width = shoulder width × consumption of transverse seam (number of stitches)

5. Total number of hanging shoulders = hanging shoulder length × straight density