How do I measure my bra size?

Measure your band size snugly around your ribcage, directly under the bust, and your bust size around the fullest part. The difference between the two determines the cup: roughly one cup size per inch (1" = A, 2" = B, 3" = C, and so on).

What is sister sizing?

Sister sizes share the same cup volume with a different band — a 34C has the same cup capacity as a 36B or a 32D. If a bra fits in the cup but the band is too tight or loose, move to the sister size rather than just changing the cup.

Why does my size differ between brands?

There is no universal sizing standard: brands cut differently, and US, UK, and EU systems label cups differently above D. Treat a calculated size as a starting point and rely on fit checks for each brand.

How do I know a bra fits correctly?

The band should sit level and snug on the loosest hook, the center gore should lie flat against your sternum, and the cups should contain everything without spillage or gaping. The band — not the straps — should provide most of the support.

How often should I re-measure?

Whenever weight changes noticeably, after pregnancy, or about once a year — band and cup needs drift more than most people expect. Bras themselves also stretch with wear, which changes how the same size fits over time.

Bra Size Calculator

Calculate bra size based on measurements and sizing charts. Free, fast, accurate — no signup, mobile-friendly, works in

Body Measurements

Measurement Unit

Band Measurement

Bust Measurement

Current Fit Information

Current Bra Size (if known)

Body Type

Current Fitting Issues (Check all that apply)

Measuring Tips

• Measure without a bra or with a non-padded bra
• Keep the measuring tape parallel to the floor
• Don't pull the tape too tight - it should be snug but not constricting
• Take measurements at the end of the day when your body is at its largest
• Have someone help you measure for better accuracy

Recommended Bra Size

32D

4.0" difference cup volume

Band Size

Around ribcage

Cup Size

Bust projection

Sister Sizes to Try

These sizes have the same cup volume:

30DD34C

Alternative Sizes

Try these if the main size doesn't fit perfectly:

32C32DD30DD34C

Style Recommendations

• Try different styles to find what works best for you
• Ensure the band is snug but comfortable
• Cups should fully contain breast tissue without gaping

How it works

Bra size combines a band measurement and a cup measurement. The band comes from your snug underbust measurement; the cup comes from the difference between your bust (fullest point) and band — each inch of difference is roughly one cup size.

Band & cup

Band = underbust measurement        Cup = bust − band  (≈ 1 inch per cup)

underbust: snug measure under the bust
bust: measure across the fullest point

Worked example

Underbust = 32 in (band 32)
Bust = 35 in

Difference = 35 − 32 = 3 inches
3 inches ≈ C cup

Approximately 32C.

Good to know

Sizing differs between brands and countries, so treat the result as a starting point and try styles on.
Cup size is relative to the band — a 34B and 36A hold a similar volume (sister sizes).
A well-fitting band does most of the support work and should sit level and snug.