Drill- Size- for-Cutting-Tap-Calculator-(inches)
MThD  inch TPI Coarse DSize inch
MThD  inch TPI  Fine DSize inch
Drill-Size-for-Forming-Tap-Calculator-(inches)
MThD  inch TPI Coarse DSize inch
MThD  inch TPI  Fine DSize inch

MThD - Major Thread Diameter;   TPI - Thread per inch;  DSize - drill size