It’s not - unfortunately, even professionals often use it wrong. the “K” refers to columns of pixels, in thousands.
2K was never used as a term for a consumer resolution, it only existed as DCI 2K really.
4K in the original form of DCI 4K is 4096x2160. But consumer screens are usually 16:9, so in consumer 4K we keep the 2160, but divide it by 9 and multiply by 16 to get 3840.
It’s not - unfortunately, even professionals often use it wrong. the “K” refers to columns of pixels, in thousands.
2K was never used as a term for a consumer resolution, it only existed as DCI 2K really.
4K in the original form of DCI 4K is 4096x2160. But consumer screens are usually 16:9, so in consumer 4K we keep the 2160, but divide it by 9 and multiply by 16 to get 3840.