A very useful pattern alteration to add to your skillset: a Full Bust Adjustment (FBA) for a dartless shirt. This one can be used when you’re making the Onyx Shirt, but can be used on any sort of bodice without darts, in both knits and woven fabrics. I’ll show you the FBA on View A of the Onyx shirt, you can find the tutorial for View B here. If you have any questions, let me know in the comments. Before you start, please read When Do You Need a Full Bust Adjustment to decide whether you need and FBA to begin with.
A full bust adjustment on a dartless shirt is done by slashing and spreading the pattern out until you have the extra width and length across the bust that you need. This creates a new bust dart, that you can then leave in or take out by slashing again and moving the side seam back in.
What you need
- front pattern piece of a pattern without darts (like the Onyx)
- straight ruler
- extra pattern paper
Step 1: Prepare pattern piece
Start with drafting in the seam allowances on the armhole and side seam. They are 5/8″ (1.5 cm) for the side seam and 3/8″ (1 cm) for the armhole on the Onyx Shirt. Then hold the pattern piece to your body and determine your apex (that’s Latin for peak or top, so in this case a fancy word for nipple). Mark it on the pattern.
Step 2: Draft and shift
Starting from the apex mark, draft a line towards the side seam (red line 1). Draft a second line from 1/3 of the armhole to the apex and then straight down to the hem (green line 2). Draft a third line (blue line 3) from the center front to the green line.
- Cut the green line from the hem to the apex and up to the armhole stitching line (yellow dot).
- Cut the armhole seam allowance to the yellow dot, but not completely through.
- Cut the red line from the side seam to the apex, but not completely through.
- Cut the blue line.
Anchor the main piece while you shift the side seam down and right. Keep the pattern flat. The amount you create between the green lines should be half the amount you need. Keep the green lines parallel to each other. When you have that piece in place, anchor it and shift the blue one down until it matches at the hem.
Step 3: Fill
When you have your pieces in the right position, fill the gaps with extra pattern paper and tape them down.
If you would do an FBA on a bodice with a bust dart, you would now have a larger bust dart then before. In this case we have created a dart where there wasn’t any. You have two options: you can redraft the dart and sew it, or you can eliminate the dart altogether. If you have added a lot in this FBA it might be best to leave the dart. Even in knits you can leave the dart in. It will give you a shirt that curves with your body instead of creating a boxy shape. But it’s a matter of personal preference, eliminating the dart might be preferable if you don’t want to break up a pattern in your fabric for instance.
If you want to keep the dart continue to Step 4, if not then continue to Step 5.
Step 4: Redraft dart
If you want to keep the dart, you have to redraft it. Draft two lines from the apex towards the side seam. Now make this triangle smaller, so the point is between 1 and 2″ (2.5-5 cm) away from your apex. Add a dart hat at the side seam so the side seam will line up when you sew the dart. This is the dart that you’ll sew. The grey areas in the illustration show where you’ve added room by making this adjustment.
Step 5: Redraft and cut out dart
If you want to eliminate the bust dart, you have to redraft it. Draft two lines from the apex towards the side seam (purple lines 4). Cut out the dart along these lines.
Step 6: Shift again
Cut along the green line 3 from the hem to the apex (yellow dot), but not through. Close the dart by pivoting at the apex. Tape in place.
Step 7: Redraft side seam
Since you now have an enormous waist dart, you have to redraft the side seam (pink line 5). It is easiest to take the original side seam to do this. Trace it on a piece of pattern paper and match the traced seam with the original. Stick a pin through the point where you closed the bust dart (yellow dot), and rotate the traced side seam clockwise. The amount you take off at the hem should be the same amount you added when you closed the bust dart. This is indicated by the arrows with the asterisk.
If you do not want to add any width to the hem at all, you can also take in this line further by redrafting it further inwards. Do not do this by pivoting or you will add too much at the armscye. Just redraft the side seam from the pivoting point down as you would when grading between sizes.
Fill up the little triangle at the armhole with pattern paper. Cut off the excess paper at the side seam. Trace the original hem line, redraft it and fill up the gap. The grey areas indicate where you have added room in the pattern.
Step 8: Pivot armscye
While you now have more room at the bust, the armscye has become larger. The last step is to pivot the armscye at the shoulder to meet the top of the pink line. This will prevent you from having to adjust the sleeve pattern. When you pivot at the shoulder, the point pivoting out will rise slightly. Re-draft the last part of the curve so it meets the top of the pink line. Check that the outer corner of the shoulder and the bottom corner of the armscye both have an angle of 90°.
You now again have a bodice without darts, but with more room at the bust as indicated by the red outline and grey areas in the illustration below.
Before you cut your fabric, measure the front and back side seams and add length to the back pattern piece. It’s quite an alteration, but worth it if it gives you a great fitting dartless shirt! If you have any questions, please leave a comment.
Other full bust adjustments
I’ve also written tutorials on full bust adjustments of other types of bodices:
- How to do a small full bust adjustment for princess seams
- How to do a large full bust adjustment for princess seams
- How to do a full bust adjustment on a pattern with waist darts