To be precise, you'll want to clear an area extending at least 4 meters (a little more than 13 feet) away from the television. That's the back edge of the space to be taken into account by the Natal sensors. In terms of width and height, the field of vision naturally expands as it moves from the Natal device to that back edge, ending up a little more than 4 meters wide and 2.7 meters high (about 8 feet, 10 inches).