What Is 80B? What Does 34/75 Mean? A Quick Guide to Common Bra Size Questions

If you often search for what is 80B, what does 34/75 mean, is 70C the same as 32C, what is 32B, or how big is 36B, you are not alone. The most confusing part of bra sizing is usually not the cup letter itself, but how the number and letter work together. This guide answers the most common size questions in a quick, simple way.

Why are bra sizes so confusing?

Bra sizes are often confusing because the same size may appear in cm-based sizing, inch-based sizing, and cup letters at the same time. That is why you may see labels such as 70C, 75B, 80B, 32C, 34B, 36B, or 34/75B.

The logic is actually consistent:

• The number refers to the band size.
• The letter refers to the cup size.
• A label such as 34/75 usually shows the same band size in two sizing systems.

So the more useful question is not “how big is a B cup?” but what is the difference between 80B, 75B, and 70B? The same cup letter can fit differently when the band size changes.

If you want a fuller size overview, you can start here: How to Read Bra Sizes

What is 80B? The most common size question answered first

80B means an 80 band with a B cup. In common international bra size conversion, 80B is often close to 36B.

But the useful part is not only knowing that 80B = 36B. It is understanding that:

• 80 is the band size.
• B is the cup size relative to the 80 band.
• 80B does not represent every B cup.

This means 80B, 70B, and 75B are not the same. They all use the B cup letter, but because the band size changes, the overall size also changes.

What does 34/75 mean?

34/75 usually means the same band size is shown in two sizing systems. It combines inch-based and cm-based band labels in one size mark.

• 34: inch-based band size
• 75: cm-based band size
• 34/75B: a 34/75 band with a B cup

This mixed label is common in many Asian markets because shoppers may be familiar with both systems. You may also see 32/70, 34/75, 36/80, or 38/85.

The important point is that 34/75 only describes the band, not the full bra size. You still need the cup letter, such as A, B, C, or D, to understand the complete size.

Is 70C the same as 32C? What is 32B? How big is 36B?

Here is a quick answer to several common bra size conversion questions.

You can start with this basic band conversion:

• 32 ≈ 70
• 34 ≈ 75
• 36 ≈ 80
• 38 ≈ 85

Then add the cup letter. That is how you get conversions such as 32B = 70B, 34C = 75C, 36B = 80B, and 38B = 85B.

What is the difference between 70B and 75B? Is C cup big?

These two questions are often misunderstood because many people think the cup letter alone tells the full size. It does not.

What is the difference between 70B and 75B?

The simplest answer is:

• 75B has a larger band than 70B.
• 75B also has more cup volume than 70B.

So they are not different only because of the number. The full size changes. This is why remembering only that you wear a “B cup” is usually not enough.

Is C cup big?

There is no single answer. Whether a C cup looks big depends on the band size. For example:

• 70C and 80C are both C cups, but they are not the same overall size.
• C describes the cup difference relative to the band. It is not a fixed standalone volume.

Instead of asking “is C cup big?”, a more useful question is: does my current band + cup combination fit comfortably?

If the size looks right but still feels uncomfortable, what could be wrong?

Many people check the conversion and then run into another problem: the size looks correct, but the bra still does not feel right.

This can happen for several reasons:

• The band is too loose or too tight.
• The cup is too shallow, too deep, or not suitable for your breast shape.
• Different brands use fabrics with different stretch levels.
• You matched the size label but did not do a fit check.

If your size looks correct but still feels uncomfortable, you can read next: Why Your Bra Feels Too Tight or Too Loose

Conclusion: You do not need to memorize every bra size — start with the band, then read the cup

If you only want the key takeaways, remember these points:

• 80B is commonly close to 36B.
• 34/75 shows the same band size in two sizing systems.
• 70C is commonly close to 32C.
• 32B is commonly close to 70B.
• 36B is commonly close to 80B.
• B85 is commonly close to 38B.
• Do not read B, C, or D alone. Always read the cup letter with the band size.

If you want to understand the full size logic, go back to the main size guide. If you already have your bust and underbust measurements, use the official size guide to find your starting size.

Once you have a clearer starting size, you can also explore Best Selling styles later. It is usually easier to shop after you understand the size logic first.