determing how big monitor is?

is there away to tell how big the monitor is whether its a 19' or 21' ect.?

Check the definition of Twips maybe helps ?

The physical dimensions of the screen generally don't matter for software purposes, though you may be able to convert the model number for certain monitors to a size. A lot of monitors, howver, show up as generic hardware. The Gateway VX700, for example, is a 17" monitor, and current Dell monitors have model numbers reported. Generic monitors, however, are named by their maximum resolution.