I'm trying to calculate implied volatility for the following put option:
Stock price = 185.55 Strike = 180 Option price = 3.00 Days to expire = 63
I've run the numbers through here http://www.option-price.com/implied-volatility.php using a risk-free rate of zero and get 17.57.
My calculations are based on the formula from here How can the implied volatility be calculated? using yoonkwon's answer. The formula doesn't use risk free rate (or strike price) so I'm using a risk-free rate of zero in the above webpage.
Formula from above link:
My calculations look like this:
sqrt((2 x 3.1415)/.17260) x 3/185.55 = 9.75
Any ideas what I'm doing wrong?