Bra AtlasBra sizing, measured and sourced

30D sister size chart, conversions and measurements

30D is a small band with a D cup. Its nearest sisters are 28DD and 32C, with the same cup volume on different bands.

Bra Atlas fitting card

30DUK · same in the US

Measures about 30 in underbust and 34 in bust. Same cups as 28DD and 32C.

UK
30D
US
30D
EU
65D
FR
80D
AU
8D
JP
E65

Same cups 28DD30D32C

Every sister of 30D

  • 26ETighter band by 4 in, 2 cup letters up (US 26DDD, EU 55F)
  • 28DDTighter band by 2 in, 1 cup letter up (US 28DD, EU 60E)
  • 30DThis size (US 30D, EU 65D)
  • 32CLooser band by 2 in, 1 cup letter down (US 32C, EU 70C)
  • 34BLooser band by 4 in, 2 cup letters down (US 34B, EU 75B)

By Rai Ansar · Sizes computed by the Bra Atlas engine · Sources and checked dates · How the sizes are calculated

28DD: band 28 in, same cup volume. Shown: a woman with fair skin, freckles and wavy copper hair in a powder blue bra.

28DD

tighter band

30D: band 30 in, same cup volume. Shown: a woman with deep brown skin and a rounded afro in a rose bra.

30D

your size

32C: band 32 in, same cup volume. Shown: a woman with tan skin and long dark curls in a black bra.

32C

looser band

Same cups, three bands: 28DD, 30D, 32C hold the same cup volume.

Tape measurements that give 30D

Computed by the Bra Atlas engine with the measured-band method, and checked by running each pair back through it.

Underbust and bust for 30DThese are examples from our measured-band rule; other calculators can round fractional measurements differently.
Snug underbustFullest bustResult
29 in (74 cm)33.5 in (85 cm)30D
29.5 in (75 cm)33.75 in (86 cm)30D
30 in (76 cm)34 in (86 cm)30D
30.5 in (77 cm)34.25 in (87 cm)30D

Our +4 comparison gives 34AA for 30 in underbust and 34 in bust. With an odd 29 in underbust and a 33 in bust we print 30C/D; our fixture-backed model of calculator.net's unpadded row gives 30D. How the +4 and measured-band methods work.

What is particular about 30D

Our recorded 30 in / 34 in test

One of our 10 test measurements was 30 in underbust, 34 in bust. A Bra That Fits and calculator.net both printed 30D, and so does our engine. Our +4 comparison pads the band to 34 and takes the cup from 34 − 34 = 0: a 34AA.

In other label systems

Our conversion follows the Victoria's Secret and Wacoal international charts: UK 30D is US 30D, EU 65D, France 80D and Australia 8D. Japan is roughly E65. M&S's US chart differs, printing UK 30D as US 30C.

Which sister to try

If a 30 band feels too tight, 32C holds the same cup volume on a band 2 in longer. If a 30 band rides up, 28DD is the tighter sister.

30D in every system

30D and its sisters on six labelsEach row has the same sister-size volume index. These are conversion-model labels, not proof a brand makes each size; band 26 is extrapolated beyond our cited guides.
UKUSEUFRAUJP (approx.)
26E26DDD55F70F4EG55
28DD28DD60E75E6DDF60
30D30D65D80D8DE65
32C32C70C85C10CD70
34B34B75B90B12BC75

Other sizes and tools

Sources

Each source was opened and checked on the date shown, or on 25 September 2026. Where sources disagree, the page says so instead of picking one silently.

  1. A Bra That Fits calculator (community calculator of r/ABraThatFits): we submitted 18 measurement pairs in 6 systems on 25 September 2026; raw synthetic fixture outputs are linked from the methodology
  2. calculator.net, Bra Size Calculator: 10 measurement pairs run in a browser on 25 September 2026
  3. Wikipedia, "Bra size": UK and US cup ladders, the +4 method, EN 13402 and JIS cup steps
  4. OneMall, "Japanese Bra Size Conversion" (11 September 2026): JIS cups in 2.5 cm steps; JP letter about one above the US letter
  5. Victoria's Secret Customer Care, "Size & Fit: International Size Chart (Outside the U.S.)": US sizes sold; bands 30 to 44, cups AA to DDD; US DDD = UK E (opened 25 September 2026)
  6. Freya, "International Bra Size Chart & Bra Sizing": band and cup tables in UK, EU, FR, AU/NZ, US and JP (opened 25 September 2026)
  7. Marks & Spencer US, "Bras size guide": UK, AU/NZ, US/CA, EU and FR conversion table (opened 25 September 2026)
  8. Wacoal, "International Size Guide": UK AA to GG paired with US AA to J; AUS/NZ keeps FF and GG; band and cup rows are separate, not a stock list (opened 13 October 2026)