How many cc's should I reduce to downsize from an E to C cup?

Dear MGoldie,
breast implant type and sizing selection is a complicated process and requires a detailed consultation that includes a discussion of your goals, a detailed examination, and a lengthy discussion. But the decision will always start and end with the patient. When it comes to sizing, we have all of our patients find 3 photos of their desired breast size. We ask for naked breast photos because clothing can obscure the true size (push up bras). Next, we consult with patients and go over the photos and take detailed breast measurements during a physical exam. Next, we using a sizing algorithm to determine a range of implants that will work based on the exam and the measurements.Lastly, during the operation, we use silicone sizers in the operating room to see how the size actually looks in the breast. We sit the patient up in the operating room, while asleep of course, and compare the sizer result with their desired look photos. If it is too small, we start the process over with a slightly larger implant. We don't stop until we get the perfect match.Of all of my breast augmentation patients, every one of them has been happy with their size due to this detailed and meticulous process. You don't want to invest time and money into a result that is either too big or too small.You should discuss your concerns with a board-certified plastic surgeon and make sure that your surgeon understands your goals.
Daniel Barrett, MDCertified, American Board of Plastic SurgeryMember, American Society of Plastic SurgeryMember, American Society of Aesthetic Plastic Surgery

Implant size is often determined by patient's breast base width. When downsizing implants, there is not a set formula for determining the best implant size. Breast imaging software may help. Rough estimate often used is 150cc/cup size. Similarly there is not a universal bra cup size, each brand of bras tends to be unique.

Each cup is roughly 150 cc's. To reduce from an E to a C ( E-DD-D-CC-C) probably means to remove the implant. The smallest implant made is 150 cc's. If you truly don't have much breast tissue, then I suspect your bra size might be incorrect.

Most plastic surgeons don’t rely on cup size because it tends to be somewhat subjective.
Personally, I prefer to work with pictures understanding what a patient looks like and what they’re trying to achieve it.
Follow up with the surgeon who did your augmentation or schedule a few in person consultations with other plastic surgeons in your community.
We can’t really give you an answer based on the information provided
Best,
Mats Hagström MD