Welcome to Smogon! Take a moment to read the Introduction to Smogon for a run-down on everything Smogon, and make sure you take some time to read the global rules.
Stat Calculator formulas (assuming 0 IVs, 0 EVs, and a neutral nature) From base stat:
stat = (base stat x 2) + 5 From stat:
base stat = (stat - 5) / 2