Wondering how to calculate your bra size for the Willowdale Bra or Loftus Bralette? Here’s our guide and bra size chart to help you choose your ideal size.

Jump to another post in this series:

1. Bra fitting guide overview
2. How to choose your bra size
3. How to make a test bra
4. How to adjust the back band
5. How to adjust the gore/bridge (Willowdale only)
6. How to adjust the cups
7. How  to adjust the center insert (Loftus only)
8. How to adjust the side seam angle
9. How to adjust the straps
10. How to adjust the underwires (Willowdale only)
11. Adjusting the level of support and comfort
12. How to make an asymmetrical bra
13. Additional bra making resources

Cashmerette has two bra patterns designed to support and lift big boobs in band sizes 28-54 and cups C-J, all while looking absolutely fabulous (It’s a lot to ask of a bra, but they are up to the task!) 

The Willowdale is a full frame, underwire bra sewing pattern while the Loftus is a non-underwire bralette sewing pattern. 

If you have big boobs and you want to start with a bra sewing pattern that’s most likely to fit you right out of the gate, the Cashmerette bras are for you.

The first step to making a bra that fits is to calculate your ideal starting size. Bra sizing varies SO MUCH from country to country and from brand to brand, and your ‘regular’ bra size may not be your Cashmerette size. So we’ve put together this guide to help you find your starting size. Let’s get on with it!

Step 1: Take your measurements

Since bra sizing varies considerably, we recommend choosing your Cashmerette size based on your measurements. So let’s start by taking our measurements.

There are two key measurements you’ll need to take to select your size: full bust and underbust. It’s important to take these measurements at the start of every project, and try to wear your most supportive bra while doing so, if you have one (if not, just go with your best option!).

1. Your full bust is measured at the bust apex, which is the fullest part of your bust. This is the part that would hit the wall first if you walked directly into a wall, and may or may not be your nipples.

2. Your underbust is measured directly below your breasts, at the narrowest part of your rib cage, where your bra band will sit. Hold the measuring tape taut but be sure to breathe out.

Step 2: Determine your size

Use your two measurements and the bra size chart below to identify your bra size.

If your measurements put you between sizes (ex: 47.5″ underbust), round up to the nearest whole number.

Important note: this chart cannot be used to determine sister sizes (more on that below).

If you don’t see a size at the intersection of your measurements, you may still be able to create your ideal size! Skip ahead to the section titled “What if your measurements put you outside of the size range?”.

Step 3: Determine your wire size

This is required for the Willowdale Bra only, if making the Loftus Bralette, skip to step 4.

Use your Willowdale size that you identified in Step 2 to figure out what wire size you’ll need. The Willowdale has been designed for use with a rounded, regular underwire such as the regular heavy duty underwire from Porcelynne.

Step 4: Make a muslin

We’ve worked hard to design a bra that will fit you well out of the gate, but boobs can vary so much in shape and size, and it’s impossible to capture the true shape of your bust with two measurements. So once you’ve determined your ideal starting size, the best thing to do is to make a muslin (test version) to check the fit.

Here is where bra fitting is a little more tricky than regular garment fitting. The fabric that you use for a bra can have a radical impact on fit—as in, you could achieve a perfect fit with one fabric, and then you make a different one and it barely fits at all; this is much more so than when you’re fitting a top or a dress. For that reason, the IDEAL approach is to use the exact same fabrics for your muslin as you intend to use for your final bra. By doing that, you’re ensuring that your fitting process will result in a bra that fits at the end.

You need to make an entire bra to get the best sense of the fit, because the various tensions through the fabric and elastic make a big difference, especially for large cup bras like the Willowdale and Loftus.  If you want to be able to reuse your elastics and notions, you can baste them onto your muslin and remove them once you’ve assessed the fit.

Once you’re able to try on your bra, refer to our bra fitting guide to determine what (if any) adjustments you would like to make.

What if your measurements put you outside of the size range?

If you fall outside the range of sizes included, it may still be possible to use this pattern to create a bra that fits.

For example, let’s say you have an underbust measurement of 36” and a full bust measurement 48”.

According to the size chart you do not fit into one of the pre-determined sizes. You can use what’s called “sister sizing” and the wire chart (not the size chart!) to modify an existing pattern to fit. Sister sizes are different bra sizes that share the same cup volume or wire size.

Step 1: Determine your band size

Use your underbust measurement to find your band size in this chart:

Band size	28	30	32	34	36	38	40	42	44	46	48	50	52	54
Underbust measurement (in)	28-29	30-31	32-33	34-35	36-37	38-39	40-41	42-43	44-45	46-47	48-49	50-51	52-53	54-55
Underbust measurement (cm)	72-76	77-81	82-86	87-91	92-96	97-101	102-106	107-111	112-116	117-121	122-126	127-131	132-136	137-142

In our example, the underbust measurement of 36″ would be a 36 band.

What do you do if your underbust measurement falls outside of the chart above?

• If your underbust is an even number, that is your band size.
• If your underbust is an odd number, subtract 1 from your underbust. That is your band size.

Step 2: Determine your cup size

To find your cup size, subtract your full bust measurement from your band size and use this chart:

Difference between full bust and band size		Cup size
inches	cm
3″	8	C
4″	10	D
5″	13	DD
6″	15	E
7″	18	F
8″	20	G
9″	23	H
10″	25	I
11″	28	J

What do you do if the difference is less than 2″ or greater than 11″?

• A difference of 1″ would be an A cup size and a difference of 2″ would be a B cup.
• For differences greater than 11″, continue going up the alphabet.

In our example, a 12″ difference between the band and full bust would be a K cup.

Step 3: Find where your size would be on the wire chart

Note: While the Loftus bralette does not use underwires, you can still use the wire chart to determine sister sizing.

Use the wire chart to find where your size would be.

The 36K in our example would be the highlighted space in the wire chart:

Step 4: Find the closest sister size

Reading across this chart, you can see that the 36K has sister sizes of 38J, 40I, 42H, etc. because they all share the same wire size. Choose the closest one—in this case, the 38J.

Step 5: Adjust the band size

Once you’ve selected the closest sister size, you can use that size pattern and wire size, but you’ll need to adjust the band size up or down depending on what you need.

For the Willowdale Bra:

To modify the band by one size, add or remove 1/2″ from the side seam of the front bands and 3/8” from the side seam of the back band. To modify the band by two sizes, add or remove 1” from the sides seam of the front band and ¾” from the side seam of the back band.

You will need to check that the length of the two seams is still the same.  The front band seam may now be longer than the back seam. If necessary, extend the top of the back band up to match the length of the front seam.

For the Loftus Bralette:

To modify the band by one size, add or remove 3/4″ from the back band. To modify the band by two sizes, add or remove 1.5” from the back band.

Once you’ve made your pattern adjustments, you can make up your muslin to check the fit!

Sizing FAQs

Can I use the Cashmerette size calculator to find my Willowdale or Loftus size?

The Cashmerette size calculator can help you find your size in Cashmerette garments, but unfortunately it won’t work for your bra size.

My Cashmerette bra size is different from my usual bra size. Which should I go with?

Bra sizing varies dramatically around the world and by brands, so go with your Cashmerette size (as determined by your measurements) which may not be the size that you’re used to wearing or making.

Can I use my Willowdale size for my Loftus?

The Loftus and Willowdale Bra’s use the same size charts and are designed for the same sizes so yes, if you have determined your sizing in the Willowdale you can use that to find a good starting point for the Loftus.

Do I need to figure out my size before purchasing the Willowdale or Loftus?

Nope! All of the sizes are included in the pattern, which accommodates full bust from 31″ to 65″ (79 to 165 cm) and underbust from 28″ to 55″ (72 to 142 cm).

Are these US sizes, European sizes, or what?

There’s so much variation between bra sizing from country to country and company to company, so we recommend identifying your size using your measurements, and the instructions we’ve included in the pattern for choosing your size! You will likely find your recommended size is similar to your RTW size, but even if it’s not, don’t worry! Your measurements are the best guide to start with.

I still need help choosing my bra size! What should I do?

We’re happy to help! You can email us directly with your full bust and underbust measurements at hello@cashmerette.com.

Jump to another post in this series:

1. Bra fitting guide overview
2. How to choose your bra size
3. How to make a test bra
4. How to adjust the back band
5. How to adjust the gore/bridge (Willowdale only)
6. How to adjust the cups
7. How  to adjust the center insert (Loftus only)
8. How to adjust the side seam angle
9. How to adjust the straps
10. How to adjust the underwires (Willowdale only)
11. Adjusting the level of support and comfort
12. How to make an asymmetrical bra
13. Additional bra making resource