http://www.oxm.co.uk/64671/xbox-one-and-kinect-2s-exact-size-cable-length-revealed/
Shocking news, everybody - the Xbox One is, indeed, slightly larger than the Xbox 360. A whole 6.3 cm longer, in fact. Forget making space beneath your television - you're going to need a living room extension to accommodate that behemoth. Add in the new Kinect sensor, and you might as well just knock a wall down and mount your flatscreen on the wall across the street. Honest.
The details arrive care of a "confirmed Xbox one dev" on Reddit, as noticed by Gamepur. Those who, like me, have trouble with numbers may prefer the below video, in which we show new and old iterations of Xbox side by side. Or one atop the other, rather. Ooh, matron.
Console (LxWxH):
13.1" x 10.8" x 3.1"
33.3cm x 27.4cm x 7.9cm
Kinect 2 (LxWxH):
9.8" x 2.6" x 2.63"
24.9cm x 6.6cm x 6.7cm
Kinect cable approx. 9.5 feet (2.9m) long
Edit: Measured with a tape where the precision is 1/8" so all values are an approximation.
For reference, the Xbox 360 Slim measures roughly 27cm by 26cm by 7.8cm. Size matters?