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Bra Size Calculator

Bra Size Calculator

Get accurate bra size measurements with international conversions and fit guidance

Measure snugly under your bust, where the band sits

Measure around the fullest part of your bust

How to Measure

Band: Measure snugly under bust
Bust: Measure around fullest part
Wear a non-padded bra for accuracy
Keep the measuring tape parallel to floor

Finding the Right Support: The Bra Size Calculator

Finding a comfortable and supportive bra is a common challenge, as studies show that a large majority of women wear the wrong size. A proper fit is essential not only for comfort and appearance but also for breast health. A bra that is too tight can restrict circulation, while one that is too loose fails to provide adequate support. This calculator provides a starting point for finding your correct size by using two key measurements: the band size (underbust) and the bust size (fullest part). The difference between these two measurements determines the cup size.

How Bra Size is Calculated

The two components of a bra size are the band size and the cup size.

  • Band Size: This is determined by your underbust measurement. Typically, you round the measurement to the nearest even number.
  • Cup Size: This is calculated by finding the difference between your bust measurement and your band measurement. Each inch of difference corresponds to a letter size (e.g., 1 inch = A cup, 2 inches = B cup, etc.).

Disclaimer: This calculator provides an estimated size based on standard US sizing. Sizes can vary significantly between brands. It's always best to get professionally fitted or try on different sizes and styles to find your perfect fit.

Frequently Asked Questions

What are 'sister sizes'?

Sister sizes are alternative bra sizes where the cup volume remains the same. For example, a 34C has the same cup volume as a 32D and a 36B. If a bra fits in the cup but the band is too tight, you could try its sister size with a larger band (36B). If the band is too loose, try the sister size with a smaller band (32D).

How often should I get measured?

It's a good idea to get measured for a bra every year or two, or whenever you experience significant weight changes, pregnancy, or are starting a new exercise regimen, as these can all affect your bra size.

How do I know if my bra fits correctly?

The band should be snug and level around your torso, not riding up your back. You should be able to fit two fingers underneath it comfortably. The cups should fully contain your breast tissue without any spilling over the top or gaps. The center panel should lie flat against your sternum.

What is the difference between US and UK sizing?

US and UK sizing are the same up to a DD cup. After that, they diverge. UK sizing continues with E, F, FF, G, etc. US sizing often goes from DD to DDD, then G, H, etc. This can cause significant confusion, so it's important to know which system a brand uses.

How do I take my measurements accurately?

For the band measurement, wrap a soft measuring tape snugly around your ribcage, directly under your bust. For the bust measurement, wrap the tape measure around the fullest part of your bust. Ensure the tape is level and not too tight for both measurements.

Why is the band size so important?

The band provides the vast majority (around 80%) of the bra's support. The shoulder straps are only meant to provide about 20% of the support. If the band is too loose, the weight of the breasts is transferred to the shoulders, which can cause pain and discomfort.
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