bake chicken breasts according to their size: bake 5-6 ounce breasts for 13-16 minutes, bake 8 ounce breasts for 16-19 minutes, bake 11-12 ounce breasts for 22-26 minutes. check that chicken has reached an internal temperature of 165deg f by inserting an instant read thermometer into the thickest part of the meat.