full bust adjustment
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A Full Bust Adjustment adds extra room in the bust area without changing the fit of the shoulders, neckline, or upper chest. It helps the garment sit smoothly over your curves and prevents pulling, gaping, or strain across the bust.
This adjustment can be done before making a toile if you already know you need it, or after your toile if the fit makes it clear that more room is needed.
What this adjustment is
A Full Bust Adjustment increases the width and length over the bust so the fabric can travel smoothly over fuller curves. It does this by:
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adding width at the bust
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adding length so the front doesn’t lift
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keeping the neckline, shoulders, and armhole in place
It’s one of the most transformative adjustments for dressmakers.
Choose your pattern size based on your high bust, then add room with an FBA.
When you need this adjustment
You may need an FBA if:
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your bust measurement is larger than your high bust size
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garments pull or strain across the bust
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the front hem lifts or tilts upward
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buttons gape
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armholes feel tight at the front
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darts point too high or too low
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the waist seam sits higher in the front
Why this issue happens
Most patterns are drafted for a B‑cup (sometimes C‑cup).
If your bust is fuller than the draft:
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the fabric has to travel further over the bust
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the front becomes too short
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drag lines radiate from the bust apex
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the waistline lifts at the front
An FBA adds the space the pattern didn’t include.
Before You Begin: Choosing Your Cup Size
We covered how to choose your sewing cup size — and how to measure it accurately — in the Fitting Foundations module.
If you’re unsure which cup size your pattern is drafted for, or how to calculate your own sewing cup size, revisit that lesson here:
👉 Flat Pattern Adjustments - Bust Adjustments
This will help you decide whether you need a Full Bust Adjustment, a Small Bust Adjustment, or no adjustment at all.
If the pattern doesn’t list a drafted high bust measurement
Some pattern companies only list the full bust the pattern is drafted for (e.g., “Drafted for a 34" bust”).
If the high bust isn’t shown, you can estimate it using a simple, universal rule:
👉 Subtract 2" (5 cm) from the listed full bust measurement.
This gives you a working drafted high bust measurement, which helps you:
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choose the correct starting size
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understand how the pattern was proportioned
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decide whether you need an FBA or SBA
Example:
Pattern bust: 96 cm
Drafted high bust estimate: 96 − 5 = 91 cm
If your own high bust is close to 91 cm, you’re a good match for that size.
If your high bust is larger, you’ll likely need an FBA.
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How to know how much to add
The amount you add in your Full Bust Adjustment depends on how much bigger your full bust is compared to the bust the pattern was drafted for in your chosen size.
It is not based on the difference between your own high bust and full bust.
Here’s the clear, step‑by‑step method.
Step 1: Choose your pattern size using your high bust
Patterns are drafted for a specific cup size (often a B‑cup).
This means the full bust measurement on the size chart assumes a certain high‑bust‑to‑full‑bust difference.
So:
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Measure your high bust.
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Choose the pattern size whose full bust measurement is closest to your high bust measurement.
This gives you the size that will fit your shoulders, neckline, and upper chest correctly.
Step 2: Find the pattern’s full bust measurement for that size
Look at the size chart and note the full bust measurement for the size you just selected.
If the pattern doesn’t list a drafted high bust, you already added the correct section earlier:
Estimate the drafted high bust by subtracting 2" (5 cm) from the pattern’s full bust.
But for calculating the FBA amount, you only need the pattern’s full bust for your chosen size.
Step 3: Compare your full bust to the pattern’s full bust
Now calculate the difference:
Your full bust−Pattern full bust (your size)=extra room needed
This tells you how much extra space the pattern needs to fit your bust comfortably.
Step 4: Divide by 2
Because the pattern piece represents half your body, divide the total difference by 2.
This gives you the amount to add to the pattern piece itself.
Full example
Your high bust: 96 cm
Your full bust: 102 cm
The pattern is drafted for a B‑cup, which assumes a 5 cm difference between high bust and full bust.
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Choose your size by high bust
You look at the size chart and choose the size where the pattern full bust = 100 cm, because:
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Pattern drafted full bust (100 cm) − assumed 5 cm = drafted high bust 95 cm, which is the closest to your 96 cm high bust.
This gives you the correct size for your shoulders and upper chest.
2. Compare your full bust to the pattern’s full bust for that size
Your full bust: 102 cm
Pattern full bust (your chosen size): 100 cm
102−100=2 cm total extra needed
3. Divide by 2 (because the pattern is half the body)
2÷2=1 cm per side
👉 You will add 1 cm in your FBA on the pattern piece.
How to Do a Full Bust Adjustment on a Pattern With Darts
This is the classic FBA used on most woven bodices with a side bust dart.
1. Identify your sizes
Use the size chart to find your bust/chest, waist, and hip sizes.
Beginner tip: Circle or highlight your sizes on the pattern envelope or PDF size chart so you don’t lose track of them.
3. Mark your key points
Use a pencil to lightly mark:
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your bust size at the bust line
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your waist size at the waistline
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your hip size at the hip line
any other relevant levels (e.g., upper arm, thigh)
Beginner tip:
Highlight these key points so they stand out clearly before you start drawing.
5. Blend both front and back pieces
Side seams must match in both length and shape.
Repeat the same blending on the front and back pieces so they sew together cleanly.
Beginner tip: Place the front and back pieces together (paper against paper) to check the curves align.
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2. Find the nested size lines on the pattern
Multi‑sized patterns have several outlines printed on top of each other. Locate the lines that match your sizes at each key point.
Beginner tip: Use a highlighter to trace the size lines you’ll be working with. This makes them much easier to see and reduces overwhelm.
4. Draw your new seam line
Using a pencil, connect your marked points with a smooth, curved line that follows the general shape of the original pattern line.
You’re not drawing straight lines between dots — you’re redrawing the pattern’s natural curve, just in a slightly different place.
Tips for success:
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Follow the shape of the original line
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Use a French curve or pattern ruler
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Keep the line gradual and flowing
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Avoid sharp corners or sudden changes
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Draw lightly first, then firm up the line once you’re happy
This new line becomes your personalised size.
6. Check intersecting pieces
If your new seam changes the length or shape of any edges, adjust the matching pieces too:
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waistbands
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facings
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collars
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pockets
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yokes
Anything that attaches to your new seam must match your new line.
7. Cut the pattern along your new blended line
Once you’re happy with your pencil line, cut along it. This is now your actual pattern edge — the one you’ll use to cut your fabric.
Before you cut fabric, check:
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Did you add the correct amount?
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Is the centre front still straight?
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Does the dart point stop short of the apex?
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Are the dart legs even?
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Does the side seam match the back bodice?
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Is the armhole unchanged above the hinge?
Common mistakes to avoid
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Adding too much length but not enough width
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Letting the centre front tilt
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Placing the dart point too close to the apex
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Forgetting to true the side seam
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Changing the armhole shape
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Skipping the toile