Answer : A diploma or degree in interior design usually takes about three years of full-time study to complete. However, there are many different ways to get into the industry, and shorter or longer courses may be available depending on your chosen path. For example, if you already have a degree in another field, you may be able to complete a one-year certificate program in interior design. Or, if you're interested in becoming an interior designer but don't want to go to school, you could look into apprenticeships or internships instead.