What Does 30B Bra Size Mean? A Complete Guide for Women

Unhooked India
Oct 2
6 min read

Bra shopping can feel overwhelming. Between confusing numbers, letters, and inconsistent sizing across brands, it’s no wonder so many women end up with bras that don’t fit the way they should. One size that often creates confusion is 30B.

What does it mean? How does it compare to other sizes? Is it really “small”? And, most importantly, how can you find bras in this size that actually fit and flatter your body?

In this guide, we’ll break down everything you need to know about the 30B bra size, from measurements and fit to misconceptions and styling tips. We’ll also share why Unhooked India’s 30B bra collection is one of the best places to shop for this size in India.

What Does 30b bra Size Mean?

Every bra size is made up of two parts: the band size and the cup size.

The number (30) refers to the band size. This is the measurement of your ribcage, just under your bust. A 30 band means your underbust measurement is approximately 30 inches (76–77 cm).
The letter (B) refers to the cup size. This is determined by the difference between your bust measurement (the fullest part of your chest) and your band measurement. A B cup means there’s a 2-inch difference (about 5 cm) between your bust and underbust.

So, a 30B bra size means you have a smaller ribcage (narrow band) with moderate bust projection that’s about 2 inches larger than your ribcage measurement.

30B Bra Size in Inches and Centimeters

It’s easier to understand 30B when we break it down into numbers:

Band size (30): 30 inches (76–77 cm) around the ribcage.
Cup size (B): Bust is 2 inches (~5 cm) larger than the band.
Total bust measurement for 30B: Around 32 inches (~81–82 cm).

Quick Conversion Chart

Measurement	Inches	Centimeters
Band (30)	30 in	76–77 cm
Cup (B)	+2 in	~5 cm
Bust	32 in	~81–82 cm

These numbers give you the foundation, but how a 30B looks and feels depends on your body frame, proportions, and the bra design.

You May Also like: What Does 28B Bra Size Mean?

Is 30B a Small Size?

A common question women ask is: Is 30B small?

The short answer: not really.

The size 30B often gets labeled as “small” because people focus only on the “B” cup. But cup letters don’t represent a universal size. A B cup on one band size is not the same as a B cup on another band size.

For example:

A 30B cup is smaller in volume than a 34B cup.
A 30B cup has about the same volume as a 32A cup or a 28C cup.

So while the band is narrower, the bust proportion is balanced. On a petite frame, 30B can look quite full and proportionate. It only seems “small” when compared to larger band sizes.

Sister Sizes of 30B Bra

Knowing your sister sizes is essential if you ever struggle to find 30B bras. Sister sizes have the same cup volume but different band sizes.

For 30B, the sister sizes are:

28C (tighter band, same cup volume)
32A (looser band, same cup volume)

This means that if you can’t find a 30B in a style you love, you can try one of these and still get a similar fit.

Find your Sister Size: Bra Sister Size Finder

30B vs Other Sizes: A Comparison

Here’s how 30B compares with other nearby sizes:

30B vs 30A → Same band, smaller cup (less bust volume).
30B vs 30C → Same band, larger cup (more bust volume).
30B vs 32B → Wider band, same cup letter, but different fit.
30B vs 28B → Narrower band, same cup letter.
30B vs 34A → Similar volume, but fit and proportions differ.

This shows why you can’t just focus on the cup letter. Both the band and the cup matter.

How 30B Looks on Different Body Types?

A bra can drastically change the visual fit from body shape to body shape.

On a petite frame, a 30B often looks fuller and more naturally balanced.
On a taller, broader frame, it may appear to be smaller because of the wider chest proportion.
On athletic bodies, a 30B can provide a nice, sleek look that feels comfortable without bulk.

This is why two people can wear the same bra in the same size and look completely different. Size cannot interpret look; the proportions of body play a role in this.

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How to Measure for a 30B Bra?

Finding out if 30B is your true size starts with accurate measurements.

Measure your band size: Place a measuring tape around your ribcage, just under your bust. Keep it snug but not too tight. If you get 30 inches, that’s your band size.
Measure your bust size: Wrap the tape around the fullest part of your chest.
Calculate the difference: Subtract your band size from your bust measurement.
- 1 inch difference = A cup
- 2 inch difference = B cup
- 3 inch difference = C cup

So if your bust measures 32 inches and your band measures 30 inches, you are a 30B.

Common Misconceptions About 30B Bra Size

Let’s address some myths:

“30B means flat chested” → Not true. It’s about proportions.
“30B bras don’t exist” → They do, though they’re harder to find in some stores.
“B cup is the same across all bands” → Incorrect. A 30B is not the same volume as a 34B.

Understanding these misconceptions helps women stop comparing sizes and instead focus on fit.

International Conversions of 30B

If you’re shopping internationally, 30B will look different on size charts.

US / UK → 30B
EU / France → 65B
Australia / New Zealand → 8B

Knowing these equivalents helps when you’re browsing global lingerie brands.

Try our Free tool: International Bra Size Converter

Best Bra Styles for 30B Size

Not every bra style works equally well for every size. For 30B wearers, certain styles tend to provide the best support and shape.

T-shirt bras → Smooth, seamless, perfect for daily wear.
Plunge bras → Great for low necklines and adding lift.
Balconette bras → Wider set straps that create a rounded shape.
Push-up bras → Enhance cleavage for smaller busts.
Bralettes → Comfortable, wireless options for lounging.
Sports bras → Important for narrow bands, look for compression styles that keep movement minimal.

Fit Tips for 30B Bra Size Wearers

Even if you know your size, the wrong fit can ruin the experience. Keep these tips in mind:

Always try the bra on the loosest hook when new. It should feel snug but not tight.
The band should sit level across your back, not ride up.
The cups should lie flat against your chest, with no gaping or spilling.
Straps should provide support but not dig into your shoulders.
Don’t hesitate to try sister sizes if the exact size isn’t comfortable.

A well-fitting bra can make all the difference in comfort and confidence.

Why Finding 30B Bras Is Harder?

Many mainstream brands in India don’t carry smaller band sizes like 28 or 30. This is why women who are actually 30B often end up wearing 32A or 32B, which don’t fit correctly.

This leads to problems like:

Bands riding up because they’re too loose.
Cups gaping or spilling.
Lack of proper support.

That’s why specialized collections like the Unhooked India 30B Bra range are so valuable—they cater to sizes often overlooked by larger brands.

Best 30B Bras in India

If you’re looking for the best bras for 30B size, the dedicated collection at Unhooked India is the perfect place to start.

The 30B bra size page includes:

Non Padded & Non Wired in Cotton Spandex Fabric with Paisley Print
Padded Balconette Designer Bra
Non Padded Designer Lace Bra
Padded Lightweight Soft Fabric Bra
Padded Designer Eyelash Lace Bra

Unlike generic lingerie stores, Unhooked India ensures that smaller band sizes aren’t left out. This means you can find both functional everyday bras and stylish, confidence-boosting pieces in 30B.

Signs 30B May Not Be Your True Size

Even if you measure as 30B, there are signs that you might need a different size:

Gaping cups → Cup too big (try 30A).
Overflowing cups → Cup too small (try 30C).
Band rides up → Band too loose (try 28C).
Straps digging in → Wrong strap adjustment or wrong style.

It’s worth experimenting until you find the size that feels comfortable for your unique shape.

Conclusion

The 30B bra size is often misunderstood, but it’s a very real and very common size. It represents a narrow ribcage with a B cup bust difference, and it can look proportionate and full on petite frames.

The key is understanding measurements, knowing your sister sizes, and choosing bra styles that flatter your body type. And while many stores don’t stock this size, you don’t have to compromise.

Discover all the best 30B bras at Unhooked India, from everyday essentials to stylish options designed specifically for small band sizes.

With the right fit, you'll not only feel comfortable, you'll continue to look and feel confident in your own body.