Interior design is about designing those spaces in which people live and work. These spaces could include offices, hotels, schools, airport terminals, theatres and private residences. Interior design post-graduate programs are aimed at those students who wish to achieve a higher level of specialization in this discipline. Broadly speaking, you could expect a masters in interior design course to take one year to complete if studying full time and two years to complete if studying part time. This of course is dependent on whether you need to complete any preparatory course work which will be a function of your previous studies.