Source: https://en.wikipedia.org/wiki/2K_resolution
> Another resolution that is often referred to as 2K is 2560 × 1440 (1440p) however that is a common mistake in marketing[12] and is called QHD by the DCI.
It is a mistake to refer to 2560x1440 as 2K.
People calling 1080p "2K" is a pet peeve of mine. 2.5K is a more appropriate name for 2560x1440, if you want to use that naming convention, but I think just saying 1440p is simpler.
