Well the number of subjects in diploma program will mainly depending on various factors like the specific diploma course which you are choosing different diploma courses have different subject . for example diploma in Engineering will have a different set of subjects compared to Diploma in computer science.  longer diploma programs May have more subject or the specific board or institution which offers the diploma may have its own set of requirements typically have 4 to 6 core subjects for semester . They may also have subjects like the languages English  subjects like history geography etc if we want to find out the exact number of subjects for specific diploma course you can search it in the below link and get your information

DIPLOMA