The Science Behind Breast Size Differences

Comparing Breast Sizes: Understanding Variations, Fit, and Body Confidence

When it comes to breasts, there is no “normal” size—only unique bodies with individual proportions. Whether you’re a 30A or a 40H, breast size comparison is often misunderstood, largely due to media portrayal, inconsistent sizing standards, and lack of education. As lingerie experts, we believe that understanding how sizes compare helps women make informed choices, embrace body positivity, and find bras that truly fit.

Let’s break down how breast sizes differ, what cup letters really mean, and why comparison should empower—not confuse or discourage—you.

Understanding the Basics: Band + Cup = Size

A bra size is made up of two key components:

• Band size (e.g., 32, 36, 40): Measurement around the ribcage, directly under the bust.

• Cup size (e.g., A, C, DD): The difference between the band and bust measurements.

Each cup size represents an inch of difference:

• 1 inch = A cup

• 2 inches = B cup

• 3 inches = C cup
  …and so on.

So, a 32C and a 38C are not the same volume—even though the cup letter is the same. This is why cup sizes must always be understood in relation to band size.

Cup Volume Comparison Chart

Here’s how cup volumes compare across sizes:

This is called sister sizing—where the volume remains the same even though the size label changes. It’s key when comparing breast sizes between people or trying to find the best fit.

Common Breast Size Comparisons Explained

1. 32B vs 36B
   While both are labeled "B" cup, the 36B has a larger cup volume. The 36B is designed for a bigger torso and holds more breast tissue.

2. 34D vs 30DD
   These have nearly identical cup volumes. The difference is in band size—30DD is for a smaller ribcage and more projection.

3. 38C vs 34DD
   Again, similar volume—but the 34DD is made for a smaller frame, and will offer a snugger band.

Other Factors That Impact Size Perception

Breast size isn’t just about measurements. Here are a few other things to keep in mind:

• Breast Shape: Full-on-top, full-on-bottom, east-west, and shallow shapes all change how size appears and how bras fit.

• Projection vs Width: Some breasts project outward, while others spread more across the chest—changing how they look in clothing.

• Height and Frame: A D cup on a petite woman appears larger than the same size on a taller, broader-framed person.

• Symmetry: Most women have one breast slightly larger than the other—completely normal and manageable with proper bra fitting.

Expert Fitting Tips for All Sizes

• Get Measured Annually: Breasts change with age, weight, hormones, and pregnancy.

• Avoid Letter Fixation: Don’t focus on the letter—focus on how the bra fits.

• Try Multiple Styles: A 36D might fit you better in a balconette than in a plunge.

• Watch the Band: It should be snug and supportive, lying parallel across the back.

• Cup Fit Test: The cups should fully enclose your breast tissue without gapping or spillage.

Embracing Size Diversity

Breast size comparison shouldn’t be about ranking or insecurity. Whether you wear an AA or an H cup, your size is simply a reflection of your anatomy—not your femininity, beauty, or worth. The lingerie industry has made great strides toward inclusivity, but true empowerment begins with understanding your own body.

At Olivia Paisley Intimates, we believe every woman deserves lingerie that fits her—not the other way around. Our collection is designed to support every curve, with inclusive sizing and a focus on comfort, elegance, and confidence.

Looking to find your best-fitting bra?
Explore our inclusive sizing range at Olivia Paisley Intimates and discover bras that honor your natural shape—with zero compromise.