Sundial - what are the outside measurements of your sit-bones?

The rule of thumb I've heard is to have 1 or 2 cm margin to the outside of each sit-bone for a comfy saddle that lets you weightbear on the bones rather than on soft tissue.

My 180mm sits never land on the nice cushy part of any chamois, but they are nicely supported by my Brooks B67. Once you figure out the width range of the various saddles it makes shopping a whole lot easier.