December 2017 is the 50th month of the Xbox One being on sale. In the latest month the gap grew in favor of the Xbox 360 by 547,534 units. In the last 12 months the Xbox 360 has grown its lead by 1.92 million units. The Xbox 360 currently leads by 1.05 million.
Both consoles launched in November. The Xbox 360 launched in November 2005, while the Xbox One launched in November 2013. The Xbox One has sold 36.37 million units, while its predecessor the Xbox 360 sold 37.43 million units.