Is your bra size out of stock? Discover your equivalent sizes

Are you crazy about a bra but it's not in your size? Good news! There might be a solution, and you could have up to two perfect alternatives to get it.

Surely it has happened to you sometime: you find a bra you love, with that lace you were looking for, your favorite print or color, the cup shape you know looks wonderful on you, and just when you're about to buy it... your bra size is out of stock!

Or even worse: you discover that this specific model is not manufactured in your usual size or cup size.

Before giving up on it, we want to show you one of the tricks we use most often at Singular: equivalent bra sizes, also known as sister bra sizes.

Knowing your equivalent sizes can give you two alternatives very close to your usual size, which is especially useful when a bra is out of stock or when a particular band and cup combination is not manufactured.

And yes, Singular girls: no matter what bra size and cup size you have, knowing your equivalent sizes can save you from more than one tight spot.

Equivalent sizes work for different bra types

You can use this trick for almost any type of bra: for minimizer bras, for plus size or full cup bras, for push-up or super push-up bras, and even for sports bras and nursing bras.

The important thing is to know your usual bra size well, the one where the band and cup fit your body correctly.

From there, we can look for its equivalents.

What are equivalent bra sizes?

Equivalent bra sizes are sizes that combine a different band with another cup letter to maintain approximately the same breast volume.

It's much simpler than it seems:

If you go down one band size, you go up one cup letter.

If you go up one band size, you go down one cup letter.

That's why a 100C, a 95D, and a 105B can work as sister or equivalent sizes.

It doesn't mean that all three sizes are exactly the same. The band changes, and the cup letter also changes, but we aim to maintain approximately the same cup volume.

Equivalent bra size chart

Take a good look at this chart we've designed for you because it will help you quickly find your equivalent bra sizes:

Find your usual size and check the sizes on both sides. We'll explain it with examples so you'll understand it right away.

What is the equivalent size of a 100C?

Imagine your bra size is 100C and the bra you love is only manufactured up to a B cup.

Don't rule it out yet!

Find 100C in our chart. You'll find these three sizes:

95D ← 100C → 105B

Therefore, your two closest equivalents would be 95D and 105B.

If that bra is only manufactured up to a B cup but is available in a 105B, you already have a possible alternative to try.

The 105B will have a slightly larger band than your usual 100C and a smaller cup letter, but it will maintain approximately the same cup volume.

And you also have the opposite alternative: 95D, with a smaller band and a larger cup letter.

100C → usual size

95D → equivalent with smaller band

105B → equivalent with larger band

See how that bra that seemed impossible might still have a solution?

Equivalent sizes for plus-size bras and large cups

This trick is especially useful when we talk about plus-size bras, full cup bras, or large cups, because some specific band and cup combinations can sell out faster.

Let's go with another example we had in our original article.

Imagine you wear a size 95H.

You've found the perfect bra, but the 95H is out of stock. However, that model is manufactured in many other sizes and cups.

Look for 95H in our chart. You can check if its two closest equivalents are available:

90I ← 95H → 100G

Therefore, if you usually wear a 95H, you can consider a 90I or a 100G, provided that bra is manufactured in those sizes.

90I → smaller band
95H → usual size
100G → larger band

This greatly expands the possibilities of finding a bra when we use large cups. However, for large sizes and cups, we recommend paying special attention to the sizing system used by each manufacturer, because cup nomenclature can vary between brands.

What is the difference between my usual size and its two equivalents?

This is probably the most important question in the entire article.

Let's go back to our 100C.

Its equivalents are:

95D – 100C – 105B

What changes between them?

Mainly, the band.

The 95D has a smaller band than the 100C.

The 105B has a larger band than the 100C.

By modifying the band, we also modify the cup letter to maintain approximately an equivalent volume. And now comes the trick we use at Singular and that we want you to remember.

The Singular three-hook trick

When choosing a new bra in our usual size, at Singular we use the reference that the band should be correctly fastened on the middle hook.

And why do we like this trick so much?

Because it leaves room on both sides.

If you wear that bra a lot and the fabric stretches over time, you'll still have a tighter hook to move to.

And if your body changes, you lose or gain a little weight, or you simply need to adjust the band slightly at some point, you still have room to adapt it.

But in addition, these three hooks are precisely what allow us to play with the two equivalent bra sizes.

If your usual size is a 100C

The 100C should fit you correctly, following our Singular trick, using the middle hook.

If you choose a 95D

The 95D has a smaller band, so it will be narrower.

To compensate for this difference, we can use the outermost hook, that is, the loosest of the three.

If you choose a 105B

The 105B has a larger band, so it will be wider.

In this case, we can compensate by using the innermost hook, that is, the tightest of the three.

95D → loosest hook

100C → middle hook

105B → tightest hook

And this is precisely why at Singular we talk about two possible equivalents very close to your usual bra size.

Do equivalent sizes have the same cup?

Here we want to explain something important so that you truly understand how a bra size works.

When we go from a 100C to a 95D or a 105B, we cannot literally say that the cup is identical, because we are changing the letter and also the band.

What we try to maintain approximately is the cup volume.

95D ≈ 100C ≈ 105B in cup volume

But they are not three identical bras.

The pattern of each model, the width of the underwire, the depth of the cup, the fabric, and the brand itself can also influence how it fits us. That's why equivalents are a fantastic tool for finding alternatives, but we should always check how the bra ultimately adapts to our breasts.

How do I know if an equivalent bra size fits me well?

Although the chart tells us that two sizes are equivalent, our body always has the last word.

When you try an equivalent bra size, pay special attention to these points:

The breast should be completely enclosed within the cup, without spilling out at the top or sides.
The cup should also not gape or leave empty spaces.
The band should stay in place, without riding up excessively at the back.
If the bra has underwires, they should correctly encircle the breast and not dig into it.
The straps should assist in support without digging in or bearing all the weight by themselves.
And, above all, you should feel comfortable and well-supported.

A size chart guides us a lot, but two women with the same size can have different breast shapes. And two bras of the same size can fit us differently depending on their pattern.

Which equivalent size should I choose?

It will depend on which of the two is available and how that particular model adapts to your body.

If you wear a 100C, your first alternatives will be:

95D, which will have a smaller band and will initially be worn on the loosest position.

105B, which will have a larger band and will initially be worn on the tightest position.

That's precisely why we always recommend starting with the two immediately adjacent equivalents to your usual size.

Although mathematically we can continue looking for more sister sizes, the further we move away from our original size, the more the band changes and the greater the fit differences can be. For us, the two sizes immediately on either side of our size are the most interesting alternatives.

When to use a sister size bra?

Knowing your bra sister sizes can be especially helpful when:

Your usual size is out of stock.
The bra you want isn't manufactured in your exact size.
A specific cup size is out of stock, but other combinations are available.
You wear a large bust size and want to expand your options.
A particular style has a slightly different band fit.
You've fallen in love with a bra and want to explore all possibilities before giving up on it.

But remember: a sister size is an alternative to try, it doesn't mean you should automatically change your usual size.

Your bra size is still your reference size

This is also very important.

If your usual size is a 100C and you can perfectly wear a specific bra in a 95D, that doesn't mean all your bras from that moment on have to be a 95D.

Your usual size remains your reference.

Bra sister sizes help us expand possibilities, especially when a style is out of stock or not available in our size.

Furthermore, each brand uses different patterns.

A minimizing bra may fit one way, a push-up another, and a sports bra may have a completely different construction. That's why we always insist that size is our guide, but the final fit on our body determines if we got it right.

Bra Sister Sizes: Quick Chart

If you still find it a bit complicated, remember this simple rule:

Smaller band → larger cup letter.

Larger band → smaller cup letter.

95D ← 100C → 105B

90I ← 95H → 100G

Always look for your usual size in our equivalency chart first and check the two immediately adjacent options.

Frequently asked questions about bra sister sizes

What size is equivalent to a 100C?

The two closest sister sizes to a 100C are a 95D and a 105B. The 95D has a smaller band and the 105B has a larger band, maintaining an approximately equivalent cup volume.

Is a 95D equivalent to a 100C?

Yes, 95D and 100C are bra sister sizes. The 95D has a smaller band and a larger cup letter to compensate for the band change and roughly maintain the volume.

Is a 105B equivalent to a 100C?

Yes. A 105B is another sister size to a 100C. In this case, we increase the band size and decrease the cup letter.

If I go down a band size, what do I do with the cup?

To find a sister size, if you go down one band size, you should go up one cup letter. For example: 100C → 95D.

If I go up a band size, what do I do with the cup?

You should do the opposite: if you go up one band size, you go down one cup letter. For example: 100C → 105B.

Do sister sizes work for large-size bras?

Yes. Equivalencies can also be used for plus-size bras and full-cup bras. In fact, knowing them can be especially useful when using large cups and your specific band and cup combination is out of stock.

Can I use sister sizes for a minimizer bra?

Yes. You can also consult equivalencies for minimizer bras, although you should always check how the specific pattern adapts to your bust.

What about sports bras or push-up bras?

Also. The principle of sister sizes can be applied to sports bras, push-up bras, super push-up bras, and other types of bras, always keeping in mind that each construction can slightly modify the fit.

Will a sister size always fit me well?

Not necessarily. Bra sister sizes are very useful alternatives, but each bra, brand, and breast type is different. That's why we always recommend trying the closest equivalencies and checking the cup, band, and comfort.