Dear Ziyan,

It totally depends on which type of course you want to do.

You can check the details below

Bachelor's degree- 

BA Interior Design- Duration is 3 years

Bachelor of Architecture Interior Design- Duration is 5 years

Bachelor of Interior Design- Duration is 5 years (CEPT course)

BA Interior Architecture and Design- Duration is 3 years

Bachelor of Design (B.Des.) Interior Design- Duration is 4 years

B.Sc. Interior Design- Duration is 3 years

Diploma course

Course duration is between 1-2 years. 

Certificate course

Course duration can be between 6 months to 1 year.

Good Luck!!