How to do a full bust adjustment (FBA) on a dartless bodice.

HelenFitting & Pattern Adjustments, March Top and Dress13 Comments

How to do a Full Bust Adjustment on a Dartless Bodice

How to do a full bust adjustment on a dartless bodice.

The March Top and Dress is drafted with plenty of ease through the chest, and a full bust adjustment may not be necessary for cup sizes ranging from AA – DD. However, for those of you with a larger cup size or who desire an even better fit, this post will walk you through doing a full bust adjustment (FBA) on a dartless bodice like March!

Helen's Closet March Top and Dress Sewing Pattern, View A

We are going to cover two methods in this post. The first is a quick method for adding length to the bodice front to accommodate a larger full bust so the garment doesn’t ride up in the front. The second is a full FBA, where we add a bust dart to this dartless bodice. 

First off, do you need a full bust adjustment? March has 6” (15.2cm) of ease through the chest, so even if your bust circumference puts you in a larger size than your waist and hips, you may be okay as long as you have some ease. Consult the finished measurements chart for more info. When in doubt, the best way to assess your needs is to sew a muslin, aka toile. To do this you just need to baste the main bodice pieces together to see how they fit. Don’t worry about the center panels, sleeves, or skirt/peplum!

Let’s say your full bust measurement is 44”(112 cm), which puts you in size 18, but your high bust falls into size 14. If you make size 18 it may look too oversized, but a size 14 would only have 2” (5cm) of ease through the chest which could change the look of the dress or be too tight for your liking. To avoid either, let’s do the full bust adjustment! 

How to do a Quick FBA

This quick method is recommended for cup sizes D-E(DD), where your full bust measurement is 4-5” larger than your high bust measurement. If your full bust is 6” or more larger than your high bust (cup sizes F+), you will likely want to add a dart, in which case—see the full FBA tutorial below. 

The math:

(Your Full Bust Measurement – Full Bust Measurement of the size you want to make)/4
Note: Since we are only adding length here, not width, the calculation is a bit different than a usual FBA. We are dividing by 4, not 2.

My full bust: 44”

The pattern full bust for size 14: 40”

I will adjust my pattern by 4”/4 = 1” total. 

Add 1” to the center front of the pattern and taper up to the original side seam. 

Technical Illustration: March Top and Dress Quick FBA Method. Add length to the center front seam.

Add 1” to the center front panel so it matches the new center front bodice.

Technical Illustration: March Top and Dress Quick FBA Method. Lengthen facings to match center front.

That’s all there is to this quick adjustment! It doesn’t add any width, which works because there is already lots of ease in this garment. Adding length allows the fabric to travel more distance over the larger bust, and prevents the bodice from riding up in the front. We used this adjustment on two of our models in our March photoshoot, Nokomis and Kate. You can find more info about their samples on the March product listing.

March Top Models

How do to an FBA (Full Bust Adjustment)

You will need the top front and front panel pieces, a pen or pencil, ruler, tape, and extra paper. 

Optional: start by tracing off the top front piece onto a new sheet of paper. You can skip this if you want to work on the original and don’t mind potentially printing the pattern again. 

Technical Illustration: March Top and Dress FBA. Trace a new pattern piece.

Hold the pattern piece up to your body as close as to where it will sit when worn. It may help to draw in the seam lines (where you will stitch) on the shoulder ⅝” (1.3cm) away from the edges. Find and mark where your “apex” is—it is right where your nipple is. Don’t worry about being 100% accurate, just do your best. 

Technical Illustration: March Top and Dress FBA. Mark bust apex.

Draw three lines as follows:

  1. Starting from the apex to the side seam, roughly where you think the bust dart would look best (red line).
  2. Starting from the armscye to the apex, and then vertically down, perpendicular to the bottom (green line).
  3. Starting at the center front and  1-2” (~2.5-5 cm) up from the bottom, draw a horizontal line perpendicular to line #2 and parallel to the bottom (blue line). 

There is no hard and fast rule on where exactly these lines have to be. Just try to make sure your lines resemble the lines below.  

Technical Illustration: March Top and Dress FBA. Draw lines from armscyce, side seam, and center front.

Using paper scissors and starting at the bottom of the pattern, cut line #2 up to the apex. Pivot at the apex and keep cutting to the armscye stopping at the seam line, ⅝” (1.3cm) away from the edge. Starting from the armscye, cut into the seam allowances towards your cut line, making sure to leave a small paper hinge. 

Starting at the side seam, cut line #1 almost all the way to the apex. Be sure to leave a paper hinge here as well! If you cut your hinge, don’t sweat it – you can just pretend it is there. 

Completely cut through line #3. 

Technical Illustration: March Top and Dress Full Bust Adjustment. Cut through lines, leaving small hinges.

Put a spare piece of paper underneath your pattern piece. 

Before you start spreading the lines open, we need to know how much room to add. The equation is: 

The math:

(Your Full Bust Measurement – Full Bust Measurement of the size you want to make)/2 

Keeping with our example from above, my full bust measurement is 44”, and the size we want to make is 14, which has a full bust measurement of 40”. That means: 

(44”-40”)/2 = 2” 

We will need to add 2” to the pattern piece. This will give us a total of 4” added across the whole front bodice. This is an example only and your number will likely be different depending on your measurements. 

Let’s get back to the pattern. Start carefully moving pieces B and C out to the side. You will be adding room right where you drew line 2. At the same time, start moving piece C down so that the hemline is staying straight. This will create a gap where line 1 used to be and this is where the dart will eventually go. 

Technical Illustration: March Top and Dress Full Bust Adjustment. Spreak open cut lines.

The gap where line 2 was is most important.  The sides of this gap should always be parallel and the width should be the number from the equation above. Once you are happy, tape pieces B and C in place. 

Technical Illustration: March Top and Dress Full Bust Adjustment. Make sure to measure the gap between line #2.

Move Piece D into position so that it is the extension of the center front and is on the same straight line as piece C. Tape it down. 

Technical Illustration: March Top and Dress FBA. Tape piece underneath of open and spread lines.

You will now have a dart-like shape on the side of the pattern piece, but it is not pointing at the right spot. It needs to be redrawn to point to your apex. Using a pen and a ruler, redraw the dart to point at the apex mark (shown as line #4 in teal below). 

Technical Illustration: March Top and Dress Full Bust Adjustment. Redraw dart towards apex.

Next, “back off” the dart point ~1” (2.5 cm) and redraw the dart again to the new point. We do this so our dart does not come to a point right on the nipple and draw attention to it. Make sure the dart legs are the same length and adjust as needed by adding some length to the shorter leg. Redraw underarm seam if necessary. Add a dart hat and admire your new dart! 

Technical Illustration: March Top and Dress Full Bust Adjustment. Measure 1 inch away from apex and draw dart from that point.

The final step is to adjust the front panel piece. The full bust adjustment adds some length to the top front piece to accommodate a larger bust, so we need to add it to the front panel piece to match. Measure the distance of the gap where line 3 used to be. 

Technical Illustration: March Top and Dress Full Bust Adjustment. Measure new gap between lines #3.

This is the length that you will need to add to the center front panel. Simply add that length to the bottom of the front panel piece. 

Technical Illustration: March Top and Dress FBA. Add length to facing.

Note, if you are adding more than 2” (5 cm) in your FBA adjustment, you may find that your dart extends past the bottom of the front top pieces. 

Technical Illustration: March Top and Dress Full Bust Adjustment

This is okay. You can either cut the excess off with scissors or, if you have a serger, ignore it and cut it off when you are finishing the waist seam. 

Congrats! You just did an FBA!

About the author


Helen Wilkinson is the designer and founder of Helen's Closet Patterns. She also co-hosts the Love to Sew Podcast! Helen is obsessed with all things sewing and strives to share her passion and knowledge with the sewing community.

13 Comments on “How to do a Full Bust Adjustment on a Dartless Bodice”

  1. Hi Helen, I enjoy your blog and work!
    Sewing is more inclusive these days, I’d love to see a post about making adjustments following a double mastectomy with a flat closure. It’s tricky as broad-shouldered woman who used to have a D cup to try and understand how to accommodate my new shape in patterns. One for the suggestion box 🙂

  2. Ooh have been looking for examples of the March on people with larger busts to decide if I should try it and came across this. It’s decided!

  3. The instructions are really clear, but what I never understand with FBA instructions is what to do about the back bodice piece? The front is now longer than the back, so do I extend the back to match? Or ease it in at the side seam (there might be a lot to ease)? Any clues would be really helpful!

    1. Hi Jo!

      The front piece should not end up longer at the side seam than the back. After you sew the dart closed it will take up that extra length and cause the bottom hem to curve up towards the side seam to match the back. I hope that helps!

  4. Thanks Helen, this tutorial is brilliant for pregnant women whose bust (but not shoulders) go up a size or two.
    However, I suffer from a too-small bust and small shoulders. Like Amber, would you please consider doing a bust-down-a-size tutorial? thank you for sharing your expertise with us

  5. This is an extremely useful tutorial – most FBA tutorials cover the darted bodice or when they do cover the undarted bodice, they lead you to create a dart or extend the side seam. Thank you for creating

  6. I have learned so much from your FBA tutorials. Thank you! Another twist (for me) is how to make an FBA for a bodice with no dart, but rather with pleats or gathering at the center front neckline (or shoulder). Any advice? Thanks again.

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