Minimum size for master bathroom

Depends on your personal taste! Things to consider... Bathrooms and kitchens sell houses. You probably spend more awake time in the bathroom than you do in the bedroom. A big bathroom with tall ceilings can be drafty and cold in the winter. Unheated tile floors can suck the heat out of bare feet. It's much more functional to have the master closets tied to the bath than the bedroom.

The modern overall trend is to build smaller quality built homes. The trend in master bedrooms is to build them smaller with large master closets and well appointed master baths. I like baths broken into areas that have the bath area (shower/ tub) separate from the dressing make-up area (sink, desk) Also include a toilet/ bidet room and a linen closet. Also have at least one full length window that has nothing in front of it. The natural lighting from a full length window will amaze you.

With all this said. Cut the size of the bedroom and focus on the well appointed feng shui inspired "spa" for the master bath with a huge closet.