For example, sizing a dado blade to match the thickness of a piece of plywood or even a hardwood part can be a trial and error process. You can achieve different widths with a stack dado set by fitting different combinations of chipper blades between two trimmer blades. Though most dado sets come with a chart that tells which blades to use for various width cuts, the actual cuts can vary.
To eliminate any guesswork, I made a simple width gauge like the one shown here. It takes some time to make initially, but gives you an accurate measure for each setup.