Convert pickbox size from pixels to dwg units

[deheylen690271]

I'm writing a routine where I need to know the size of the pickbox in dwg units in order to account for the tolerance of points returned by entsel. I drew a 10"x10" box in the drawing, zoomed out until my size 10 pickbox matched the box as close as I could get it and used the following code to get the size of the pickbox in dwg units:

(* (getvar "PICKBOX") (/ (getvar "VIEWSIZE") (cadr (getvar "SCREENSIZE")))))

This code consistently returns a number close to 5 rather than 10 so it appears to me that the pickbox size is the number of pixels from the crosshairs to the edge of the box rather than the outside edges of the box. Can someone please confirm that my code is correct and that this is actually how the pickbox is sized?

Thanks for your help

[Ed Jobe]

I'm not sure about where it is measured, but a pixel is 1/72".