34D sister size chart, 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

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)

Fit problem in 34D? Convert 34D Brand charts

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

32DD

tighter band

34D

your size

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 34D**These are examples from our measured-band rule; other calculators can round fractional measurements differently.
Snug underbust	Fullest bust	Result
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

Our +4 comparison gives 38AA for 34 in underbust and 38 in bust. With an odd 33 in underbust and a 37 in bust we print 34C/D; our fixture-backed model of calculator.net's unpadded row gives 34D. How the +4 and measured-band methods work.

What is particular about 34D

Four tools, four sizes

Our measured-band engine gives 34D. Wacoal (band + 2 in for this even underbust) 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: these outputs use a longer band and smaller cup volume than our measured-band result. Recorded on 25 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. Try the nearer sister first; the size label alone does not tell you the wire shape.

34D in every system

**34D and its sisters on six labels**Each row has the same sister-size volume index. These are conversion-model labels, not proof a brand makes each size; check the brand chart before ordering.
UK	US	EU	FR	AU	JP (approx.)
30E	30DDD	65F	80F	8E	G65
32DD	32DD	70E	85E	10DD	F70
34D	34D	75D	90D	12D	E75
36C	36C	80C	95C	14C	D80
38B	38B	85B	100B	16B	C85

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.

Wacoal America, "Bra Fit Calculator": measurements in eighths of an inch; 8 synthetic pairs submitted to the calculator; 5 result pairs recorded (opened 25 September 2026)
ThirdLove, "Bra Size Calculator & Chart": bands 32 to 44, cups AA to H with half cups; 6 synthetic pairs submitted to the calculator; 5 result pairs recorded (opened 25 September 2026)
SKIMS, "Bra Size Guide": underband/overbust grid and US/UK/EU/AU cup table disagree above DD; grid skips DDD (opened 25 September 2026)
Wikipedia, "Bra size": UK and US cup ladders, the +4 method, EN 13402 and JIS cup steps
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)
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)
Marks & Spencer US, "Bras size guide": UK, AU/NZ, US/CA, EU and FR conversion table (opened 25 September 2026)