Hi Hun. I went for my pre op last night and asked this question. In terms of cup size, the Macom bra is adjustable so it’s just the back size you need to decide on. They say always go up a back size. I definitely would do as you have to wear them all day and you don’t want to risk it being uncomfortable. I’m a 34 and I’m ordering a 36 and my 2 friends were 32’s and they ordered 34’s. If you’re unsure ask your PC or order a 32 and 34 and send one back. My advice is always go up a back size and I’m sure most other girls would agree 🙂 xx