Bra Atlas

34D sister sizes, conversions and measurements

34D is the body we used to test brand tools: a 34 in underbust and a 38 in bust came back 36B from Wacoal's calculator, 36A from ThirdLove's and 38A on SKIMS's chart.

Bra Atlas fitting card

34DUK · same in the US

Measures about 34 in underbust and 38 in bust. Same cups as 32DD and 36C.

UK
34D
US
34D
EU
75D
FR
90D
AU
12D
JP
E75

Same cups 32DD34D36C

Every sister of 34D

  • 28FTighter band by 6 in, 3 cup letters up (US 28G, EU 60G)
  • 30ETighter band by 4 in, 2 cup letters up (US 30DDD, EU 65F)
  • 32DDTighter band by 2 in, 1 cup letter up (US 32DD, EU 70E)
  • 34DThis size (US 34D, EU 75D)
  • 36CLooser band by 2 in, 1 cup letter down (US 36C, EU 80C)
  • 38BLooser band by 4 in, 2 cup letters down (US 38B, EU 85B)
  • 40ALooser band by 6 in, 3 cup letters down (US 40A, EU 90A)

By Rai Ansar · Sizes computed by the Bra Atlas engine, sources checked · How this page was made

32DD: band 32 in, same cup volume

32DD

tighter band

34D: band 34 in, same cup volume

34D

your size

36C: band 36 in, same cup volume

36C

looser band

Same cups, three bands: 32DD, 34D, 36C hold the same cup volume.

Tape measurements that give 34D

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

Underbust and bust for 34DA bust within about a quarter inch of the figure shown still gives 34D.
Snug underbustFullest bustResult
33 in (84 cm)37.5 in (95 cm)34D
33.5 in (85 cm)37.75 in (96 cm)34D
34 in (86 cm)38 in (97 cm)34D
34.5 in (88 cm)38.25 in (97 cm)34D

Same body, other methods: 34 in and 38 in is a 38AA with the traditional +4 method. With an odd 33 in underbust and a 37.5 in bust we print 34D; calculator.net's rule (band rounded, cup from the raw difference) would print 34DD. Why methods differ.

What is particular about 34D

"34d sister size" gets about 2,400 Google searches a month in the US and 320 in the UK (Google Ads data, September 2026).

Four tools, four sizes

Our measured-band engine gives 34D. Wacoal (band + 2 in) gave 36B, SKIMS's chart (band + 4 in) reads 38A and ThirdLove's calculator printed 36A. 36B and 38A hold one cup volume less than 34D and 36A two less: a padded band always trades cup for band. Recorded on 26 September 2026; see brand size charts.

Where the letters split

34D reads the same in the UK and US, and so does its tighter sister 32DD. One more step, 30E in the UK, is 30DDD in the US, EU 65F.

Which sister to try

If a 34D band rides up, try 32DD. If it digs in, 36C. 38B is two steps away, and its wires sit wider.

34D in every system

34D and its sisters on six labelsEach row holds the same cup volume.
UKUSEUFRAUJP (approx.)
28F28G60G75G6FH60
30E30DDD65F80F8EG65
32DD32DD70E85E10DDF70
34D34D75D90D12DE75
36C36C80C95C14CD80
38B38B85B100B16BC85
40A40A90A105A18AB90

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. Wacoal America, "Bra Fit Calculator": measurements in eighths of an inch; calculator run with 8 measurement pairs (opened 26 September 2026)
  2. ThirdLove, "Bra Size Calculator & Chart": bands 32 to 44, cups AA to H with half cups; calculator run with 6 measurement pairs (opened 26 September 2026)
  3. SKIMS, "Bra Size Guide": underband and overbust chart, sizes 30AA to 46H, US/UK/EU/AU cup table (opened 26 September 2026)
  4. Wikipedia, "Bra size": UK and US cup ladders, the +4 method, EN 13402 and JIS cup steps