Find your bra size — band and cup, such as 34B — from your underbust and bust measurements in cm or inches, with UK/India, US, EU, French and Australian sizes, sister sizes and a snug-fit option.
📏 How to measure for bra sizeTap to see the illustrated guide
Wear a thin, non-padded bra (or none) and stand straight, arms relaxed.
Underbust: keep the tape snug and level all the way round your ribcage, right under the bust.
Bust: measure loosely round the fullest part of the bust, keeping the tape level at the back.
Breathe out normally and read the tape at the front. Use the same unit (cm or inches) for both.
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Fill in the details and click Calculate to see your results.
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Formula at a glance
How the bra size works: EU band = underbust in cm, rounded to the nearest 5 (70, 75, 80…)
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📘 About the Bra Size Calculator
Your bra size has two parts: the band (a number such as 32, 34 or 36) from the measurement around your ribcage under the bust, and the cup (a letter such as A, B, C or D) from how much bigger your bust is than your underbust.
Enter your underbust and bust measurements in centimetres or inches. The calculator uses the European sizing standard (EN 13402) that most size charts are built on, then converts it to UK/Indian, US, EU, French and Australian sizes. It also gives your sister sizes and the snug 'no-add' fit some fitters recommend.
Measure without a padded bra, or over a thin unpadded one, and keep the tape level all the way round.
🧮 Formula
EU band
EU band = underbust in cm, rounded to the nearest 5 (70, 75, 80…)
Underbust (band): wrap the tape snugly around your ribcage just under your breasts, keeping it level. Breathe out.
Bust (cup): measure around the fullest part of your bust, keeping the tape loose and level.
Enter both numbers — the calculator does the rest.
💡 Bra size chart (cm)
Underbust 63–67 cm: band 30 (EU 65)
68–72 cm: band 32 (EU 70)
73–77 cm: band 34 (EU 75)
78–82 cm: band 36 (EU 80)
83–87 cm: band 38 (EU 85)
88–92 cm: band 40 (EU 90)
💡 Cup size chart
Bust 12–14 cm (about 5 in) more than underbust: A cup
14–16 cm: B cup
16–18 cm: C cup
18–20 cm: D cup
20–22 cm: DD (UK) / E (EU)
22–24 cm: E (UK) / F (EU)
💡 Bra size conversion
UK and Indian brands use the same sizes (32B, 34C, 36D…).
US cups follow UK up to DD, then go DDD, G, H.
French/Spanish band = EU band + 15. Australian band = UK band − 22.
❓ Frequently asked questions
How do I calculate my bra size?
Measure under your bust and round to the nearest 5 cm for the EU band (75 = UK 34). Then subtract underbust from bust: 12–14 cm is an A cup, and every extra 2 cm is one cup bigger.
How do I calculate my bra size in inches?
Add 4 to your underbust in inches and round to an even number for the band. Each inch your bust is over the band is a cup: 1 = A, 2 = B, 3 = C, 4 = D.
How do I calculate my cup size?
Bust minus underbust: about 13 cm (5 in) is A, 15 cm (6 in) is B, 17 cm (7 in) is C, 19 cm (7.5 in) is D.
What bust size is 34B in cm?
Underbust 73–77 cm and bust about 89–91 cm.
What bust size is a D cup in cm?
About 18–20 cm more than your underbust. For a 34D (EU 75D) the bust is about 93–95 cm.
What are sister sizes?
Sizes with the same cup volume: going down a band means going up a cup (34C → 32D) and up a band means down a cup (34C → 36B).
What is the snug-fit (no-add) size?
Some fitters use your underbust in inches as the band with no 4 inches added, giving a smaller band and bigger cup (for example 30E instead of 34B). Try it if bands ride up your back.
Why do different brands give me different bra sizes?
There is no single global standard. Use your result as a starting point and try sister sizes.
Should I measure over a padded bra?
No. Measure without a bra or over a thin, unpadded one.
