Not everyone is a professional builder. Still, as a homeowner, you can become familiar with the standards that are used in the industry, such as the rough opening size for interior doors.
The standard sizes for interior doors will vary by manufacturer. One seller, for example, offers standard interior doors ranging from 16 inches to 42 inches wide, with heights ranging from 80 to 96 inches. Other manufacturers may have slightly different standard options.
Rough Opening Sizing
The size of the rough opening for interior doors will depend on the measurement of the door you are planning to place in the opening. Experts recommend that you build the rough opening at least 2 to 2.5 inches larger than the actual door.
If you are building a home that is handicapped-accessible, do not purchase an interior door that is narrower than 34 inches wide. For even easier access, choose interior doors with widths of at least 36 inches.