December 2018 is the 22nd month that the Nintendo Switch has been available for. During the latest month the gap grew in favor of the Switch by 981,093 units when compared to the combined sales of the 3DS and Wii U during the same timeframe. In the last 12 months the gap has grown in favor of the 3DS and Wii U by 315,480 units. The 3DS and Wii U is currently ahead of the Switch by 2.93 million units.
The 3DS launched in February 2011 (however, 3DS sales have been aligned to March 2011, since it only launched at the end of February in Japan), the Wii U launched in November 2012, and the Nintendo Switch launched worldwide in March 2017. The Switch has sold 29.64 million units, while the 3DS and Wii U have sold 32.57 million units during the same timeframe.