“whatsizeis ab” is not a standard sizing term on its own, but the closest match in common use is the way bra sizes work with letters like A, B, C, D, etc., where A and B indicate smaller cup volumes.

Quick answer

  • In bra sizing, the letter (A, B, C, D…) is the cup size and tells you breast volume.
  • A cup is smaller than B; as the letters move up, the cup gets larger.
  • The number (like 32, 34, 36) is the band size around the ribcage; without that number, “AB” or “A/B” isn’t a complete size.

If by “whatsizeis ab” you meant “what size is A vs B in a bra?”, then:

  • Roughly a 1‑inch difference between band and bust = A cup.
  • Roughly a 2‑inch difference = B cup.

Mini breakdown

1. How bra letters work

  • Bra size = number (band) + letter (cup), e.g., 34B.
  • The letter is based on the difference between underbust (ribcage) and overbust (fullest part of bust).
  • Each step up in letter is one “cup size” more volume (A → B → C → D → DD → E …).

2. What A and B roughly mean

  • A cup: about 1 inch difference between band and bust measurements.
  • B cup: about 2 inches difference.
  • Important: a 32B and a 38B are not the same volume in everyday terms, because the band size changes the actual cup volume, and “sister sizes” share similar cup volume with different bands (e.g., 34B ≈ 32C ≈ 36A).

3. If you meant something else by “ab”

“AB” could also be:

  • Part of a clothing brand like Aab Clothing (modest fashion brand), where “size” would refer to their own size chart (XS, S, M, etc.).
  • A typo or shorthand from a forum thread asking, “What size am I?” for bras, where people share band and cup measurements.

If you tell me where you saw “whatsizeis ab” (e.g., on a bra label, clothing brand, or a specific website/app), I can interpret that exact usage more precisely.