I love a good bralette but being on the bustier side- it is difficult to find one that checks all my boxes. When I decided to design and draft a new bralette, there were a few must have details that I was looking for 👇

  • Easy to sew. Great bralettes don’t have to be too complicated!
  • Supportive. I love a strappy bralette as much as the next person, but I need straps that are a bit more… substantial?
  • Easy to fit sizing. I wanted selecting a size to be simple. Measure your cup, band, and boom- bra size.
  • Just a little bit sexy. The lace finishes, plunge neckline, and peek-a-boob situations all add a little extra spice!

During testing, we really focused on getting the fit just right. It was important to me to make a bralette that was wearable for lots of different body shapes and breast sizes. Much like snowflakes- no two boobs are alike. Even each of mine have their own… personalities?

What factors can affect my cup size?

All breast shapes vary person to person and as the breasts get larger, the differences vary more greatly. Let’s talk about some of the differences that can affect your measurements and the fit of your bralette.

Breast Shape

The shape of the breast can affect play a big role in where the majority of your breast tissue lies and how that will impact your measurements and cup size. Let’s take a look at some different breast shapes in the chart below 👇

  • Round breasts have volume that is pretty evenly distributed and they sit centered to the chest.
  • Bell shaped breasts are slim at the top and full at the bottom.
  • Tear drop breasts are narrower than the bottom.
  • Asymmetric breasts can be any shape, but different sizes.
  • Wide set breasts sit further apart with a wide gap in the middle.
  • East/West breasts are fuller in the center and the the apex is closer to the sides.
  • Relaxed breasts carry all their volume in the bottom and often sit low.

As you can see with the diagrams- all these breast shapes look very different and could impact how you measure and the fit of your bralette.

Body Proportion

Just like each of our breast shapes are different, our body shape and proportion are too! When we are measuring our upper and full busts, sometimes the shape of the back can play a big factor in our measurements.

  • Wide Back. Having a broad back can affect your upper and full bust measurements. If your back is wider compared to your front it may make you measure into a larger cup size than you need.
  • Extra curves. If you have a few extra curves along your under arm and back, this can affect your bust measurements as well- putting you in a larger cup size.


I think my cup size might be off, how do I know?

Start by taking your measurements again. Here are a few extra tips to make sure you are measuring properly 👇

  • Check the scale of your measuring tape- the plastic ones can stretch out over time.
  • Measure in only a bra but not a padded or push up that will give you more volume than you normally have.
  • Hold the measuring tape firmly against the skin but don’t compress.
  • Make sure the measuring tape is parallel to the floor, both in the front and in the back.

There are also a few different ways you can measure to help you get a better average of your measurements if you feel like the traditional measuring isn’t doing the job.

Take your average measurements

Take your upper bust while you’re standing- according to the tips above. Then measure your full bust while standing straight up, bent over at a 90 degree angle, and laying on your back. Once you have recorded all three full bust measurements, add them together and divide by three to get the average.

Measure your breast volume

I am not going to go into huge detail about how to do this one because Ashley H. did a video of it that you can watch right HERE. Measuring for volume is a great way to ensure that your measurements are accurate if you have a wide or curvier back, but don’t feel like you have a lot of breast volume.

How do I select the right size for Colby?

I tried to make the sizing for Colby super simple. Your cup is based off the difference between your upper and full bust and the band is based off your under bust measurement. Once you have your measurements taken, follow the measuring guide in the pattern to select your size.

It is super important to remember that your traditional bra size (which Google says 80% of us have wrong anyways) is NOT your sewing cup size. Traditional bras are usually sized off the difference between under and full bust, whereas full and upper bust are the determining factors for Colby.

The cup size also affected by the band size. A 34B/C will be smaller than a 44B/C, but both are drafted for a difference of 2″ between the high and full bust. Also, this is a knit bralette, so fabric stretch gives a little more wiggle room in sizing as well.

A quick muslin based on the chart should always be your first step. I would recommend sewing a quick shell and basting the waistband in place before adding a lining and elastic into the seams. Once you have an idea of fit, you can adjust if you need to.

My muslin isn’t quite right, how do I fix it?

If your muslin fit isn’t perfect just yet, don’t worry! Most adjustments are pretty simple but knowing where to start can feel intimidating. Below are some common fitting problems and how to fix them.


Gaping at the side of the cup

You can adjust this by taking a larger seam allowance at the princess seam. If there is a significant amount of gaping, you can also try removing a small amount from the side seam or sizing down in the outer cup. Sometimes removing a small amount from the strap length can help as well.

More side coverage

If you have added elastic and your cup is fitting ok, but you would like a little more coverage in the side of the cup, you can get that by extending your pieces as shown.

Spillage in the center cup

If your outer cup seems to be fitting ok but you have a little bit of spillage in the center, you can size up one band size in the center cup.

Length Adjustments

If the back rides up, you can add a little length to the back piece as shown on the left. If your cup is too short, you can add length to the bottom of each of the front pieces as shown on the right. If your bra fits when you adjust it but rides up after movement, try adding elastic to the waist seam before adjusting the length.

No support or too much compression

The biggest factor in the level of support is your fabric selection. Heavier weight fabrics with firm stretch like custom cotton lycra, supplex, or athletic knits have more support than fabrics like thinner cotton lycra, double brushed poly, and bamboo/rayon fabrics. For extra support, add elastic into the seam. You can zig zag it into the seam allowance or add as you are serging in the video HERE.

Wide or curvy back

If your breast volume measurement puts you in a smaller cup size than your full bust measurement, use the smaller cup for the front and size up in the back.

Take a peek at some of these tester makes!

There have been a few questions in the Fan Group about the sizing- especially for those with larger busts. Check the fit on a few different testers all within the the same size range, 34-36 G/H.

Cotton Lycra main and lining with 1/4″ elastic in the neckline, armscyes, and waist seam.
Stretch lace and athletic knit lining with 1/4″ elastic in the neckline and the armscyes.
Heavyweight Athletic Knit main and lining with 1/4″ elastic in the neckline and armscyes.
Circular athletic knit with 1/4″ elastic in the neckline and armscyes.



Ok, I know this was a long read but if you hung in till the end, yay! I hope this helped and I can’t wait to see all of your Colby makes! If you haven’t already, you can pick up Colby and the other new releases right HERE.

Until next time, friends!

Written by petitestitchery Admin

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