The specs say it's 78"x75" (98"x75" for large version) when open. How much space you want beyond that is up to you I presume as it depends on your door position

The specs say it's 78"x75" (98"x75" for large version) when open. How much space you want beyond that is up to you I presume as it depends on your door position and layout of rest of room. If you just have a couch then that's probably a couple feet around for entrance and 4 feet for the couch. So roughly you'd want a 10' x 11' room.