if you're in 8 bits per value, then "444" is 24 bpp, "422" is 16 bpp, and
the others are 12 bpp, but those "bits per pixel" are assuming a "pixel"
is defined only in terms of the Y channel. If you do it only in terms of
UV channels, then everything is reversed, as "444" is 24 bpp, "422" is 32
bpp, and the others are 48 bpp.

It is important to state that all of the pixels are 24 bit in every YCbCr system. Each pixel can have a unique value even with the shared CbCr.