How to Figure Out Your Cup Size for Sewing Patterns: The Not-So-Complicated Way

Alright, we’re about to dive into some measuring tape action to get your sewing pattern to fit your fabulous self perfectly! This tutorial is especially useful for our pretty Kaiko dress & top , which comes in different cup sizes! This tutorial involves just a couple of key measurements—your full bust and your upper bust. But don’t worry, no math degree is required, I promise. Let’s go step by step!

What You’ll Need:

• a measuring tape (not the metal one from the toolbox but a flexible one).
• a pen and paper (or just your phone’s notes app if you’re modern like that).
• and maybe a mirror or a helpful friend to make sure the tape doesn’t slide into oblivion while you measure.

Step by step plan:

Step 1: Get your Full Bust measurement (aka, where the magic happens)

1. Wrap It Around: Take that measuring tape and wrap it around the fullest part of your bust. Think of it as giving yourself a hug—with numbers!
2. Keep It Level: Make sure the tape is straight and not sagging or riding up. You want it to be nice and even.
3. Take a Breath and Write It Down: Don’t hold your breath (seriously, don’t do that). Breathe naturally and write down that number. This is your full bust measurement.

Step 2: Measure your upper bust (No, It’s not the same thing)

1. Under the arms, over the bust: Now, measure the area right under your armpits and above your bust, where things are more compact. Wrap the tape snugly but not too tight.
2. Keep a straight line: This is your upper bust, not a roller coaster—keep that tape straight across.
3. Record that number: Write it down or log it into your phone. This is your upper bust measurement.

Step 3: Bust out some simple math
Okay, now comes the part where we do a *little* math. But don't worry, it's the easy kind.

Subtract your upper bust measurement from full bust measurement:

Full Bust - Upper Bust = Bust Difference

For example, if your full bust is 100 cm (40 inches) and your upper bust is 90 cm (36  inches), that’s:

100 cm - 90 cm = 10 cm
40" - 36" = 4"

Step 4: Consult the "magic cup size chart"

Here’s the part where we figure out the cup size you’re working with based on that bust difference. Spoiler alert: it’s not the same as your bra cup size (but wouldn’t that be nice?).

Example:

If your bust difference is 10 cm or 4 inches, congratulations, you’ve got yourself a pattern D cup.

Step 5: Choose your pattern size like a pro
1. Use your Upper Bust to select the pattern size. Patterns are made for people with B-cup busts, so this is your starting point.
2. If your cup size is more than B, you might need a Full Bust Adjustment (FBA). And if you're smaller than a B, you'll likely want a Small Bust Adjustment (SBA). Basically, if you’ve ever thought, “Why does this fit *everywhere* except my bust?”, an adjustment is your friend.

Bonus Tips (aka Things to Remember So You Don’t End Up Frustrated):

• Double-Check That Bust Point: Patterns don’t always have the bust point where *your* bust point is, so mark it on the pattern before you start cutting.
• Sew a Muslin First: Try it out on cheap fabric before cutting into your precious stash. It’s like a test drive but for your clothes.
• Cup Size ≠ Bra Size: I know, I know—it’s confusing. For bra's you need to take your full bust measurement and your under bust measurement to know your band width. Just remember, pattern cup sizes are a whole other thing.

What size to pick for our Notches patterns?

To make things a bit easier, we have made the calculations for you and put them in a nice chart! Just measure your full bust and high bust measurements, compare them to the chart and determine your cup size!

Notches' High bust measurements chart in cm

Notches' Full bust measurements chart in cm

Notches' High bust measurements chart in inches

Notches' Full bust measurements chart in inches

Example:

I have a high bust of 104 cm (41") so I look at the high bust table and see I have to cut a size 46 (US 14) as a base size for my top pattern front piece and back piece and sleeves, facing, ....

My full bust size measures 114 cm (45"). If there are no cup sizes included in the pattern I have to do a Full Bust Adjustment. If there are cup sizes included in the pattern I look at the column of size 46 of the full bust chart and see that a high bust of 114 cm (45") corresponds to an F-cup so I trace or cut the F-cup pattern piece for the upper front bodice.

And there you go! You’ve now figured out your sewing pattern cup size without tears or head-scratching. Time to grab that fabric and sew yourself something fabulous—because the fit is about to be on point! 🎉