First go to this site;
And check you're Pokemon's max stats at it's current level, as long as it's level 50 or level 100, and has either no stat experience or max stat experience. Now, it's max in that stat is considered a DV of 15. At level 50, for every point lower than max a stat is, subtract one from the DV. At level 100, for every two points lower than max a stat is, subtract one from the DV.