Less the arms length, well basically arms length if I were to place my hands flat against the screen with my arms out infront of me. But my monitor is smaller than many, it's 21.5" with 1920x1080 resolution, so fairly fine dot pitch.
I actually changed to this from a 24" one though, I prefer monitors around the 22" size, I'm not sure why exactly ...they just seem to gel with me since I can sit at my usual distance from them while keeping the entire unit easily within my view, I prefer not to have my vision totally filled with the monitor, I just feel more comfortable this way when using it for longer periods.