Ever tried on a me-made dress or top, only to find it pulling across your bust, riding up at the waist, gaping awkwardly at the armholes, or sagging at the upper chest and shoulders? Don’t worry, you haven’t done anything wrong. Your pattern might just need a full bust adjustment (AKA an "FBA").
A full bust adjustment is a pattern alteration that adds room where you need it most, around the fullest part of your bust, while keeping the rest of the garment fitting nicely. If you’ve done an FBA before on a darted or dartless bodice, you might be wondering, "What about princess seams?".
That’s exactly what we’re covering here - how to do an FBA on a bodice with princess seams - those long, curved seams running over the bust instead of darts.
We’re demonstrating on our Noa pinafore dress sewing pattern. You can use the same method on other sewing patterns with princess seams, such as the Rosa shirt + dress.
Do you need a full bust adjustment?
You might need an FBA if:
- Your bust feels squished even though the garment fits elsewhere
- You can see horizontal drag lines across the chest
- The waistline rides up at the centre front
- The fabric gapes or bunches at the armholes
A quick way to check is to compare your high bust measurement (taken around your upper chest, just under your armpits) with your full bust measurement (measured around the fullest part, usually across the nipples).
If you’re making TATB sizes 1–6 (UK 6–16 - or any size in UK 6–24 patterns in our older patterns, such as Rosa), and your full bust is more than 5cm (2in) bigger than your high bust, you’ll likely need an FBA. If you’re making TATB sizes 7–15 (UK 18–34), and your full bust is more than 10cm (4in) bigger, we'd also recommend making an FBA.
What you’ll need:
- Traced-off copy of the side front + centre front bodice pattern pieces*
- Extra paper
- Pen or pencil
- Ruler or pattern master
- Paper scissors and tape or glue
- Measuring tape
- Calico or other cheap fabric to make a toile
*Tip: Always trace off your pattern pieces before making adjustments so you can keep the originals intact.
How to do an FBA on princess seams
Make a toile (test garment) of at least the bodice of the pattern you're making in the size that matches your high bust measurement - NOT your full bust measurement. Mark your bust apex (nipple line) on both the centre front and side front pieces.
Open the princess seams on your toile at the bust to see how much extra room you need. Measure the gap between the bust apex markings – that’s how much to add to the pattern. In this example, the gap between the bust apex markings is 25mm (1in), so we'll be adding this amount to the pattern when doing the FBA.
On the side front bodice, mark the stitching lines 15mm (5/8in) in from the edge of the pattern piece along the front princess seam, armhole and side seam.
Using a ruler, draw four lines onto the side front bodice:
- Line 1: from the princess seam stitching line at the waist to the bust point (the apex point you marked earlier)
- Line 2: from the bust point to roughly 1/3 of the way along the armhole (if the armhole on the pattern you’re making is split across two pattern pieces, remember to take the full length of the armhole into account)
- Line 3: from the bust point to the side seam
- Line 4: from line 1 horizontally out to the princess seam cutting line, around 25mm (1in) up from the bottom of the pattern piece
Starting at the waist seam, cut along line 1, then pivot at the bust point to cut along line 2, stopping just before the stitching line at the armhole.
From the other side of the armhole stitching line, cut through the remainder of line 2, stopping just before the stitching line to leave a little “hinge”.
Cut through line 3 from the side seam to just before the bust point (where line 3 meets line 1) – this creates your second “hinge”.
Next, get a piece of paper slightly bigger than your side front bodice piece and draw two vertical parallel lines on it, with the distance between them the amount you want to add to the bust (measured when you tried on your toile).
Carefully place the pattern piece on top of the paper and tape the side front piece down along the front princess seam, aligning cut line 1 with one of the vertical lines drawn on the paper underneath.
Using the hinges you created earlier, gently pull at the side seam of the side front pattern piece to increase the opening at line 1 by the required amount. Make sure to increase the width evenly all the way down by aligning the moveable side of cut line 1 with the second vertical line drawn on the paper underneath. Tape or glue in place.
To make room for the width you’ve added, you’ll see that line 3 has opened, creating a "dart" – we’ll come back shortly to close this dart up, but for now, tape or glue it in place.
In pivoting the piece to add more width, we’ve created a step along the waist seam, so let’s even that out.
Cut along line 4 from the front princess seam to where it meets line 1 – we don’t need to create a hinge here, so you can cut all the way through. Slide this small square you’ve just cut down until its bottom edge is level with the bottom edge of your pattern piece, and make sure to keep the spacing the same as you did all the way along line 1. Tape or glue in place, and reconnect the waist seam and front princess seam.
Now to close the dart we opened up along line 3. Trim off the excess paper around your pattern piece so there’s about 1cm (3/8in) left around the edges. With a ruler, draw a straight line to extend line 3 all the way across the paper.
Now we need to create another hinge. Cut along line 3 from the side seam and stop just before the bust point. From the front princess seam, cut through the remainder of line 3, stopping again just before the bust point.
Using the hinge you’ve just made, pivot the pattern piece so that the top and bottom of line 3 meet and the original side seam is joined up again. Tape in place. You’ll notice that in closing line 3, you’ve opened a smaller dart along the front princess seam – place a small piece of paper underneath this dart, tape it in place, and draw a smooth curve to rejoin the front princess seam across the dart.
Now to remove the extra width that’s been added to the waist at the side seam. Mark a point along the waist seam that is the same width in from the side seam as the amount you added in at the bust. Draw in a new side seam from the point you just marked at the waist seam to where line 3 meets the side seam.
Smooth out the armhole seam if needed, and remember to transfer any notches to your newly drawn side seam.
Cut away any excess paper to leave you with a freshly altered side front bodice piece, which should look something like this:
All that’s left to do now is to lengthen the centre front bodice so that the princess seams match up when sewn together.
Using a ruler, draw two horizontal lines across your centre front bodice piece, at right angles to the grainline:
- 25mm (1in) up from the waist seam (shown in orange above)
- From the bust notch to the centre front (shown in blue above)
Cut all the way along the two lines you’ve just drawn to split the centre front bodice into 3 pieces. Label the parts 1, 2 and 3 as shown above.
Tape part 1 of your centre front bodice onto a piece of paper. Using a ruler, draw a horizontal line underneath part 1, parallel to the cut edge, with the distance away equal to the extra length added to the seam line across the small dart on your side front bodice. Tape down part 2 of your centre front bodice, aligning the top cut edge with the horizontal line you’ve just drawn, and the centre front with the centre front of part 1.
Repeat for part 3 of your centre front bodice, adding in the same amount of length added at the bottom of your side front bodice.
And that’s it - your princess seam bodice now has extra room where you need it, without throwing off the rest of the fit.
Final tips
- Always make another toile to check the fit after your adjustment. It may need a little more tweaking.
- Give your princess seams a good steamy press after sewing to help them sit nicely.
Remember: needing to make pattern adjustments is totally normal. We are all different shapes, and they’re simply part of customising your garment to suit your body.
Once you’ve nailed this, you’ll be able to sew beautifully fitted princess seam bodices again and again.
Author: Frances Wakefield
Photos: Jane Looker
Model: Rita Fitchett
