Bra Starts from Rs.199 Shop Now
Panties - Buy 3 For 599 Shop Now
Search

What’s the Difference Between 30A, 32A, 34A, 36A, 38A, 40A, and 42A Bra Sizes?

Many women believe that all A cups are the same. They think that a 30A, 34A, or even a 42A must fit the same because of the “A.” But here’s the truth—a 30A is not the same as a 42A. In fact, they’re quite different in both band length (the number) and cup depth (the letter). Though the letter stays the same, the capacity changes with the number before it.

In this guide, we’ll clear up the confusion around A-cups, explain how bra sizes actually work, and help you find the A-cup that truly fits you.

How Bra Sizes Work?

Your bra size has two parts:

  • Number (band) — this is the measurement around your ribcage just below your bust.
  • Letter (cup) — this shows how much your bust projects compared to the band.

Here’s something most women don’t know: cup volume changes as the band size changes.

So while a 30A has a very small cup, a 42A has much more volume—even though both are labelled “A.”

What Does “A Cup” Mean?

An “A” cup means your bust measurement is roughly 1 inch (2.5cm) larger than your band measurement.

But many women mistake this to mean A is a fixed size. In truth, a petite frame (30A) is totally different from a curvier frame (42A). It’s like comparing a small teacup to a shallow bowl—they both hold liquid, but one holds much more.

Common Mistakes Women Make When Choosing A-Cup Bras

Mistake #1: Focusing only on the band or only on the cup — Both need to work together. A tight band with a tiny cup or a loose band with a shallow cup will never sit right.

Mistake #2: Wearing a band that's too big and a cup that’s too small — Surprisingly, this is one of the most common fitting errors.

Mistake #3: Trusting the same size forever — body changes happen faster than we think. Your first-ever purchased size might not work today.

Mistake #4: Forgetting to re-measure regularly — Experts recommend checking your measurements every 6–12 months.

Mistake #5: Skipping the scoop and swoop — Many women don’t adjust their breast tissue into the cup properly, which causes gaping or spillage.

30A to 42A: What Each Size Means

Here’s how each A-cup differs in fit and who it usually suits best:

Bra Size Band (inches) Cup Volume Best For
30A Bra 25–26” Very small Slender, petite frames
32A Bra 27–28” Slightly larger Petite women wanting a little more comfort
34A Bra 29–30” Moderate Slim to medium builds
36A Bra 31–32” Fuller ‘A’ Every day average builds
38A Bra 33–34” Larger ‘A’ volume Broader frames, smaller busts
40A Bra 35–36” Wider + deeper cup Curvier body with a small bust
42A Bra 39–40” Fullest ‘A’ cup Plus-size frames with smaller busts

So yes, all these bras are “A cups,” but the actual cup capacity increases as the band size increases.

Why the Right A-Cup Size Matters

Wearing the wrong bra size isn’t just uncomfortable; it affects your posture, confidence, and even your health.

  • The band does most of the work. Around 80–90% of your bra’s support comes from the band, not the straps.
  • A cup fit prevents bra problems. A well-fitting cup prevents bra problems. It avoids gaping, spillage, and digging wires.
  • Better fit = better posture and shape. Clothes sit better, and you feel more confident throughout the day.

How to Measure Yourself for an A-Cup

Grab a soft measuring tape and stand in front of a mirror:

  1. Band size: Measure snugly under your bust, keeping the tape level. Round to the nearest whole number.
  2. Bust size: Measure around the fullest part of your bust, keeping the tape relaxed but not loose.
  3. Cup size: Now subtract band size from bust size. The difference tells you your cup. (1 inch = A, 2 inches = B, etc.)

Sister Sizes for A-Cups

If your current bra feels a little off, try sister sizes. These keep the cup volume similar while adjusting the band:

  • 32A ⟶ 30B or 34AA
  • 34A ⟶ 32B or 36AA
  • 36A ⟶ 34B or 38AA

This trick is especially useful if your band feels too tight or too loose.

How to Know if Your A-Cup Fits Perfectly

  1. The band sits level and doesn’t ride up.
  2. The Cups hold all the breast tissue with no gaping or spillage.
  3. The Straps stay in place without digging into your shoulders.
  4. You can fit two fingers comfortably under the band.

Styles That Work Well for A-Cups

Conclusion

An A-cup bra size isn’t a “one-size” cup. A 30A and a 42A are worlds apart in fit and volume. The key is to think of bra sizing as a two-part equation—band + cup—and find the balance that suits your body.

When your bra fits right, you get comfort, posture support, and a boost of confidence. So don’t just settle for “A”—find the right “A” for you.

Explore More