Standover is measured on bikes, inseam is measured on people. Make sure that when you measure your inseam, you jam a book or something up into your crotch, to simulate the pressure of being seated on a bicycle saddle. Measure from the top edge of the book to the floor. Since you're posting in the SS/FG forum, it stands to reason that you've perhaps been looking at some bikes with track geometry, which tend to have relatively higher standover values in order to raise the bottom bracket. Don't obsess over this measurement...if your junk grazes the top tube, just tilt the bike off to one side when you're straddling it. If you have very short legs and a long torso, you could consider frames that have a sloping top tube.