How many cc's of fat do I need to add 2 inches to my butt and 2 inches to my hips?

Dear Thrifty572481,
it is hard to tell for sure without an examination. If you are considering surgery, I would suggest you consult a board-certified plastic surgeon. Only after a thorough examination, you will get more information and recommendations.
Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery

Unfortunately it’s not quite that easy.
Total amount of projection in the end it’s a combination of many variables. The amount of fat that can be successfully grafted is highly dependent on what’s available as host tissue to support the graft.
In other words if someone does not have a sufficient fat layer to graft fat into then high-volume fat grafting procedures will lead to a high percentage of fat graft loss or failure.
There’s also connective tissue in the buttocks that can limit projection and this varies in different parts of the buttocks and from person to person.
There is no milliliter to inch formula.
I suggest having multiple in person consultations with local board-certified plastic surgeons at which time you can review providers before and after pictures. Ask providers to show you pictures of patients with similar body characteristics to your own.
When reviewing before and after pictures always confirm that after pictures were taken at least three months from the date of surgery.
In the end there are only two variables needed for quality results. These are quality candidacy combined with surgeons skill and experience.
Best,
Mats Hagstrom MD