January 2018 is the 11th month that the Nintendo Switch has been available for. During the latest month the gap grew in favor of the Switch by 239,521 units when compared to the 3DS during the same timeframe. The Switch is currently ahead of the 3DS by 939,112 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), while the Nintendo Switch launched worldwide in March 2017. The Switch has sold 14.46 million units, while the 3DS sold 13.52 million units during the same timeframe.