If your bust is smaller than a b-cup you'll want to adjust your patterns by taking out the extra fabric around the bust and making the bust dart narrower. Today we'll go through adjusting a bust dart located at the side. Our garment is fitted and has a waist seam.
Many tutorials on small bust adjustment leave you with a smaller front piece than back piece. This is not ideal since we still want the side seams to be at the sides (or a bit towards the back, definitely not the front). With this tutorial the front waist seam measurement stays constant.
1. Locate the bust apex. If it's not marked on the pattern it's usually 2 to 3 cm (about 1") from the end point of the dart.
2. Parallel to center front draw a line from bust apex to waist.
3. Draw the new center line of the dart. Also draw a line from bust apex to mid-armhole.
4. Cut along all lines.
5. Tape or put fabric weights at X and Y. Armhole and waist seam lengths are not meant to change. Move the dart legs towards each other.
6. Measure how much you are reducing from the bust width horizontally. Generally, one cup size is 2,5 cm ( 1" ) change in total bust circumference. If you're going from a b-cup to an a-cup, reduce the pattern measurement by 1,25 cm.
7. Secure pieces by tape. Since a smaller bust also requires less fabric vertically, we can now adjust the waist seam by returning it to its original shape.
8. Cut off the extra, remembering to add seam allowance.
9. Mark the original bust apex. Measure 2,5 cm towards the side seam. This is the new dart point. Re-draw the dart legs.
No other pattern pieces need to be adjusted since we haven't changed any other measurements.