Here's an Excel sheet that may be interesting. I will find out when my pin gauge set arrives, but it looks like with the dowel pins I have now, .375. .500. .625 and .750 I can measure accurately up to over an inch. The math makes sense, anyway.
You can use this in two ways, where you know the three pin sizes, and where you know the size of the hole you want to measure.
Measurements are in inches, but the spreadsheet doesn't care if you use metric, answer will be metric also.