Understanding Bra Sizing: A Complete Guide

Feb 4

Finding the perfect bra size can feel impossible, but once you understand how bra sizing actually works, it gets a lot easier. A well-fitting bra makes a huge difference in comfort, support, and how your clothes fit, but surprisingly a lot of people don’t actually know how bras are properly sized. Here’s what you need to know:

1. The Two Key Measurements: Band & Cup Size

Bra sizes consist of a band size (number) and a cup size (letter).

Band Size: The number (e.g., 32, 36, 40) represents the measurement around your ribcage, just under your bust.
Cup Size: The letter (A, B, C, D, etc.) represents the difference between your bust measurement and your band size.

2. How to Measure Your Bra Size

You’ll need a soft measuring tape.

Step 1: Measure Your Band Size

Wrap the tape snugly around your ribcage, just under your bust.
Round to the nearest whole number.
If it’s an even number, that’s your band size. If it’s odd, round up to the next even number.

Step 2: Measure Your Bust Size

Wrap the tape around the fullest part of your bust, keeping it relaxed.
Round to the nearest whole number.

Step 3: Calculate Your Cup Size

Subtract your band measurement from your bust measurement.
Use the difference to find your cup size:

  
      Difference (in inches)
      Cup Size
    
      1 inch
      A
    
      2 inches
      B
    
      3 inches
      C
    
      4 inches
      D
    
      5 inches
      DD (E)
    
      6 inches
      DDD (F)

Example: If your band measures 34 inches and your bust is 38 inches, the difference is 4 inches, meaning your size is 34D.

3. The Fit Test: Signs of a Good vs. Bad Fit

A good fit means:

The band sits snug and parallel to the ground (not riding up).
The cups fully hold your breasts without gaping or spillage.
The straps don’t dig in or slip off.

A bad fit means:

The band is too tight or too loose.
The cups gape (too big) or cause spillage (too small).
The straps constantly fall off your shoulders or leave marks.

4. Sister Sizes: Adjusting Your Fit

If your usual size isn’t quite right, you can try sister sizes, which have the same cup volume but different band sizes.

Size too tight? Go up a band size and down a cup size (e.g., 34D → 36C).
Size too loose? Go down a band size and up a cup size (e.g., 36C → 34D).

5. Different Bras, Different Fits

Not all bras fit the same—push-up bras, sports bras, and balconettes all have different structures, so you might need to adjust sizing depending on the style.

The right bra makes a huge difference in how you look and feel. If you’ve been wearing the wrong size, take the time to measure yourself properly or get fitted at a lingerie store. A well-fitting bra offers better support, comfort, and confidence—because nothing looks better than feeling good in what you wear!

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