Bra fitting question

[CharlotteStreetW1]

If a bra feels comfortable but keeps riding up, is it too big or too small?

Back is probably too big. Needs a smaller back and probably a larger cup to compensate

Yes, this ^

Thank you. Will try that.

Thirding this. On me a 36B ‘fits’ and is really comfortable when I put it on but soon rides up. A 34C is less comfortable (I can feel it around my ribs all day), but it stays put.