A Big Bedroom
In a typical house, the Building Code (Malaysia) specified that first room (usually the master bedroom) need to have a minimum of 11.7m2 in area, 1.8m2 for the area of the master bathroom.
Of course, you must not be limited by the constraint set based on the guideline and whatsoever.
Suitable room size is one which is comfortable to enclose its user and not others who will not be using the room.
The ideas that support one-size-fits-all, standardization, equal means sameness have failed and will continue to fail if repeated without even being noticed.
Especially with the building type like a house, expect a different physical (movement, anthropometry, body size), psychological (feeling), thinking, and cultural (history, experience) factors that define the suitable size of the master bedroom required.
There are also a few simple tricks in defining your master bedroom size, such as constraint fixing.
For example, determine the size of the bed that you wanted (usually a queen or a king), and then the spaces needed for you to access the bed, walk, and subsequently you can decide on the spaces needed for the activities such as reading, meditation, working, etc.
Permutating the constraints mean you can even set the size of the walkway you wanted inside the room first, before other things like the bed, the table and the chair can take place.
We must not assume and the idea of homogeneity in design thinking such as the assumption that everyone loves a big bedroom should be eliminated (some people likes small, intimate spaces).