Is 34D bra medium or large?

Is 34D bra medium or large? 

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Size Bra Size
Small 36A,34B
Medium 36B,34C, 34D
Large 34DD, 36C, 36D, 38B
X-Large 36DD, 38C, 38D, 38DD, 40B

1 more row

What celebrity has a 34C bra size? Beyoncé The Queen of Pop is said to be a 34C, but she is definitely much more a 30G-GG in my opinion. Shop 30G bras here.

Is there a 34D bra size? 

For example, if you wear a 34C, your Sister Size DOWN would be 32D. SISTER SIZE UP: One actual size larger than your current Band size AND one letter name smaller than your current Cup.

SISTER SIZE CHARTS:

34 BAND SIZE
Current Bra Size Sister Size DOWN Sister Size UP
34C 32D 36B
34D 32DD(E) 36C
34DD(E) 32DDD(F) 36D

Is D cup size considered big? For some reason, we have been brainwashed into thinking that boob sizes go from A-DD, DD being the biggest boob/bra size. DD is actually at the lower end of the scale, there is still E, F, FF, G, GG, H, HH, J, JJ, and K cup above that.