Are you talking inseam (as in pants)? If so, that is very different from standover height. An easy way to measure yourself for standover is to get a hard back book (not too thick), stand with your back against a wall, hold the book between your legs and squarely against the wall, slide it up till it doesn't slide up any further and measure from the top of the book to the floor. Do this without shoes on. I'd look for a frame with a standover height at least an inch shorter than your measurement.

One final thought. If you don't have a pretty good idea of what frame size you need from past experience and have to rely on charts, buying a mail-order bike you aren't able to ride first may not be the best idea.