Assuming the door is 36in, I'm getting 6.67ish doors deep (20ft) and 4.33ish doors wide (13ft) for a total of ~260sqft external size.
Wall thickness and irregular shaping will reduce that slightly.
If anyone has a better measurement of a hotel door, can easily adjust the numbers!
EDIT: a better way of measuring, still using the door.
36in door is illustrated with 43px. Exterior size of the room, in pixels, is 294x186. That's 6.84 doors by 4.33 doors, or ~266sqft external size.
Interior size is 275x182, or ~244sqft, with additional, minor subtractions needed for irregularity.