Bra Size Calculator
Find your perfect fit in US, UK, and European sizing from body measurements
Measurement Unit
Underbust (Band) Measurement
in
Measure snugly around your ribcage, just below the bust
Bust Measurement (fullest point)
in
Measure around the fullest part of your chest (loosely)
How to measure:
1. Underbust: tape measure snug around ribcage below bust
2. Bust: tape measure relaxed around fullest part
3. Measure in a well-fitting, non-padded bra
1. Underbust: tape measure snug around ribcage below bust
2. Bust: tape measure relaxed around fullest part
3. Measure in a well-fitting, non-padded bra
Your Bra Size
US Size
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UK Size
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EU Size
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Band Size
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Cup Size
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Measurement Difference
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Sister Sizes (same cup volume)
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Understanding Bra Sizes
Bra sizes consist of a band number (chest circumference) and a cup letter (difference between bust and band). Each inch of difference equals one cup size: 1"=A, 2"=B, 3"=C, 4"=D, 5"=DD. UK and US bands are the same; EU bands are in centimeters (~5 cm increments) with slightly different cup letters.
Sister sizes have the same cup volume but different band sizes. If a 34B fits the cup but the band is too tight, try 36A. If the band is right but cup too small, try 34C. Professional fitting is recommended for the most accurate result as bra sizing varies between brands.
lightbulb Example
Underbust: 32", Bust: 36":
1Band size: 32 (round to even)
2Cup: 36-32 = 4" = D cup
✓ Size 32D (US) / 70D (EU)
quizFrequently Asked Questions
How do I measure myself accurately for a bra size?
Use a soft measuring tape. For band size: measure snugly around your ribcage just under your bust — round to the nearest even number. For cup size: measure around the fullest part of your chest without compressing. Subtract band from bust measurement; each inch equals one cup size (0 = AA, 1 = A, 2 = B, 3 = C, 4 = D).
What are sister sizes in bras?
Sister sizes are bras with the same cup volume but different band and cup letter combinations. A 34D is a sister size to 32DD and 36C — the cup volume is identical, just the band is different. If a 34D band feels too tight but the cups fit, try a 36C for a more comfortable band with the same cup capacity.
Why do bra sizes vary between brands and countries?
Sizing systems differ by region. UK and US use the same band measurements but slightly different cup progressions past D. EU uses band sizes ~8–10 cm smaller (EU 80 = UK/US 36). French and Italian brands add a further offset. Always refer to each brand's size chart and measure yourself rather than assuming your size carries over between brands.