What is the difference between X-inches diagonal, X-inches viewable, and the modern X-inch “class” in monitors and tv's?

Question

I'm really dumbstruck by this one. I see it everywhere now, though. The last time I bought a monitor, a Samsung 1941BW, it was just 19-inches widescreen. Before that, LCD's, TV's, and CRT's where advertising "viewable" or "diagonal" area, and would often come with a sticker or logo which described the diagonal line, and where I should measure if I wanted to check for myself.

But, how the heck do I know what a 22-inch class monitor is? I just bought a TV which is 19-inch "class". What is this? It's even on laptop ads now.

Answer 1

• Diagonal: the actual diagonal corner-to-corner size of the display, measured (more or less) exactly. e.g. 13.3"

• Class: The diagonal measurement rounded to a whole number for easier discussion and marketing. e.g. 13"

• Viewable: Not generally used anymore. If you do see it these days you're either looking at a CRT monitor or it's being used synonymously with the diagonal measurement.

Answer 2

"Class" is them rounding the decimal off of the actual number. 21.7 vs 22.3, both "22 inch class". You kind of get it in laptops these days where a 15" laptop can be anything from 14.9" to 15.6".

'Viewable' went by the way-side when CRTs went away.