Full Bust Adjustment for Armhole Princess Seam Bodice

A dress sewing cup size diagram. Learn to sew inclusive size vintage, everything from full bust adjustment on vintage patterns

When your full bust measures more than 3 inches (7.5cm) than your high bust you often need to make a full bust adjustment to sewing patterns.

This simple tutorial is for patterns with a princess seam that starts from the armhole.

Don’t be intimidated but the diagrams. Trace your centre front and side front pattern pieces  onto paper and adjust cutting as shown below.  Most of the fullness is added to the side front panel.   

Measure to see how much you need to add to your pattern. If your full bust is 42″ (107cm) and your pattern is 40″ you need to add 2″  (5cm) total so halve this and you add 1 inch (2.5cm) to each side. 

sewing for larger busts

Trace your Centre front and side Front pattern pieces.

If your pattern piece does not have seam allowances included add just along armhole on side front piece.

fba princess seam

Draw a line from the point where the full bust point is to the lower edge as shown.


Draw a line from the full bust point to underarm seam as shown. draw a third line from full bust point to about a quarter way down the side seam.

Cut along the lince from lower edge to bust apex, then to underarm seam, stopping just short of the seam allowance so the pattern is still just attached.

then cut along the line from the side seam to almost the bust apex, again leaving a small hinge of paper pattern attached. 

Lay pattern piece onto another layer paper and as we are adding 1″ (2.5cm). draw 2 parallel lines 1 inch apart on the bottom sheet of paper. 

Start to arrange pattern pieces on paper as shown, arranging so the cut edges lay along the 2 parallel lines that are 1 inch (2.5cm) apart. the arm hole will raise at the bottom as the hinge opens. the lower edge of pattern will be lowered until its laid as shown.

Once the Pattern is spread as shown in diagram 6, tape to the paper. 

large bust adjustment

Cut the side front piece at the waistline and lower it down to match the side.

Cut the centre front pattern piece and lengthen to match the new longer side piece. Tape to the paper and draw around the centre front pattern  to create the new longer centre front pattern piece. 

You now need to tip back the top portion of the side front piece -sometimes I cut the hinge to the bust apex at this point as it makes it easier. 

fba large bust alterations

Snip along to the bust apex as shown so top part of the pattern piece will tip back, pivot it back to close the side and tape down. 

Draw around the new side front pieces. remove to top layer of taped pieces and cut out the new pattern pieces.

full bust adjustment

The new pattern pieces will have the extra fullness mostly at the full bust. the front will be slightly longer as the larger bust needs this for the waistline to sit correctly. Most of the extra fullness is in the side front panel. 

For very large busts you may need to add some of the fullness to the centre front seam too to keep the symmetry. This is the basic principal but adjust as the pattern and fabric drape requires.

Showing the original pattern piece and the new fuller longer pattern overlaid so you can see the underarm and side seam should be near identical to the original. The length increases to adjust over the fuller bust. Try on and check that the waist line is straight on the body. 

Busts can sit high or low, fullness at the sides or up high. The bra and shape will all make further adjustments necessary with some patterns but this is the basic principal to add fullness where you want it and avoid gaping, wrinkling and pulling elsewhere.