I've used a lot of different measuring tools, but for characters I now load the cone from the primitives menu and rotate it along the Z axis 90 degrees. That puts the tip of the cone directly at floor level, right between the character's feet. Move it along the Y axis until the tip of the cone is on the tip of the head, read the number in the Y trans field. Just like a tape measure. Michael 4 is about 6'7".