This calcultaor works well, except for the dividend. It requires an annual yield and does not allow you to enter individual dividends. That is a minor problem, unless the stock's dividend is large. I suggest making your calculations both with and without the dividend to determine the difference.A better calculator can be found at the CBOE .
Option Calculator
Given 6 of the 7 fields, this calculator computes the remaining field.
Written by Dr. Robert Lum at robertl@intrepid.com