Breast implants obviously add weight to one’s chest, just like real breast tissue would. But how much do breast implants weigh? The answer to these questions is based on the material’s density and atomic composition. This is why comparing cc (a volume measurement) does not necessarily compare to grams. (a weight measurement) Similar-sized silicone breast implants weigh slightly more than saline implants due to a greater density. But how significant are the weight differences? One cc of silicone gel weighs 0.0375 ounces. For example, a 400cc silicone gel implant would then weigh 15 ozs. (0.94 lbs) and a pair would weigh 30 ozs. or 1.875 pounds. Conversely, a cc of saline weighs 0.0325 ozs. A 400cc saline implant would then weigh 13 ounces (0.81 lbs.) and a pair would weigh 26 ounces or 1.62 lbs. The difference at 400cc would be around 0.2 pounds or about 3 ozs.