Seaweed is a strategic commodity in the area of difficulty. Seaweed in Indonesia is known for its good quality and is in great demand because it contains sources of yeast, agar and alginate, one of which is Gelidium sp. a type of red seaweed (Rhodophyceae) that produces agarophytes (gelatin). The purpose of this study was to optimize Gelidium sp. to get the best results of agar on yield value, …