Well, the little one says it’s for a small room, so I would assume something like a guest bedroom would be a good comparison. I bought several for our office because we have some fairly spacious areas, and I didn’t want anyone to feel too dried out, and it does seem to have helped, and we have even had to turn these down in some places because it’s too much for some of the smaller offices. I think it also depends how dry the air is and whether you are running a heater in the same room.