Wait. I thought 4K means 4 times the resolution of 1080P? Or 4K for the second number in the resolution, ????x4K?

My understanding is that its just a switch of numbers when the say 4k res. 1080p os 1920*1080p. For 4k they are just using the first number. Its 3840*2160p.

and it IS 4 times the resolution of 1080p

1920x1080 = 2,073,600 ; 3840x2160 = 8,294,400 ;    8,294,400:2,073,600 = 4

I belive you are correct.  4K refers to the horizontal number.

And yes, it is 4 times the number of dots as 1080p, so it could make a very good looking screen well over 80"

That's exactly what the picture states.

4K has twice the resolution in both directions (1920*2=3840, 1080*2=2160), so it has 4 times the number of pixels and thus 4 times the resolution overall.

1920 x 1080 = 2073600
3840 x 2160 = 8294400

So 4K is exactly four times 1080p. It's the pixels that count, nothing else.

edit: meh, too slow.

Going by that, it should be call 8M, not 4K?

LOL!! Hey, this thread taught me something too!!

actually they are just using the term movie makers have used for a long time for this resolution (and other compareable ones)

2048x1080 (pretty much the same as 1080p) was called 2k by movie makers