Breast reduction: 34DDD cup size, what will 400g reduction leave me at? (Photos)

Hi and thanks for your questions. After reviewing your description and photos, it seems that you potentially would be a good candidate to have a breast reduction and lift using the Bellesoma technique.  It appears that you would most likely need a 300 to possibly gram reduction in order to attain your wish size.  
Bellesoma is a new breast reduction and lift technique that seems like it would be a great fit for you.  This procedure utilizes 3-D volumetric scanning and a multi-point measuring system to design a precise surgical blueprint exactly tailored to your body and the reduced breast size that you desire. The Bellesoma procedure reduces the sagging and weight of your breast, lifts your breast and reduces areola diameter, preserves the nipple sensation and ability to breast feed, and looks as full and perky as if an implant had been placed without using any implant, so no need to compromise.  One of the huge positives of this technique is that there is no vertical incision traveling down the front of your breasts.
Some of the differences between Bellesoma and the traditional breast reduction/lift techniques:
-Bellesoma creates upper pole fullness and projection that traditionally needed an implant to achieve.
-There is NO vertical scar, only well-hidden scars in the fold under the breast, and around the areola.
-The breast is dynamically supported by attaching it to the muscle, so there is no recurrence of sagging which are expected with traditional lifts or reductions.
-The entire central portion of the breast is undisturbed, so nipple sensation remains intact and is very unlikely to be compromised giving the best possible chance for future breast feeding.
-For absolute best results, patients should have a stable weight and have a BMI under 30.
The procedure is accomplished by using the skin of the lower pole of the breast (the part below the nipple that sits in the bra cup) to shape the whole breast into a perky dome, then straps are made of the extra skin, anchoring it to the underlying chest muscle so that there is virtually no chance of repeat sagging.  The skin that above your nipple and below your collar bone is utilized to cover the perky, lifted dome that has been created and then a new (usually smaller) circular opening for the areola is placed at the high point of the cone, creating your new lifted, full and shapely breast.
From your description, you seem to be a very good candidate for this new technique and should really get the look that you are desiring without implants or unnecessary visible scars. I would recommend that you search for an ABPS board certified plastic surgeon who is also a member of the American Society of Plastic Surgeons and the American Society of Aesthetic Plastic Surgeons in your area or an area that you would like to travel to on holiday who offers the Bellesoma technique to discuss your breast reduction and possible results.
Best wishes!
Daniel Brown, MD, FACS Diplomate, American Board of Plastic Surgeons MemberAmerican Society of Aesthetic Plastic Surgeons MemberAmerican Society of Plastic Surgeons Real Self Top 500

It is not possible to provide you with a definitive answer regarding your cup size following a 400 gram reduction. There are too many variables to make this determination based on photos alone. There are many options surgeons use to demonstrate the volume of 400 grams of tissue. Your surgeon can use these tools to guide you in your decision during a consultation. 

It is very difficult if not impossible to predict a specific bra cup size.  Photos of a desired result are often more useful when discussing a goal size.  Based on your photos, I think 400 grams would leave you  smaller than your desired result.