The width of a ring is an important consideration because it alters the look and feel of the ring.  As the drawings show, as a ring gets thinner, its curvature changes to become more curved.  The drawings were made to scale, but they may not show up exactly to scale on different computer monitors.  It is best to gauge the width that's best for you by using a ruler.  In general terms, a medium width ring for a man might be in the 7mm range.  More narrow might be in the 5mm range.  A wide ring might be in the 9 to 12mm range.  Above that is pretty extreme for most people.  For ladies, a width of 3 to 6mm is common depending on ring sizes and styles.