Where do I get a correct volatility measurement of a stock for an option calculator?

Question

Or should I be calculating this myself too? Is there a way to calculate volatility? Is daily volatility considerred in a total volatility measurement?

Answer 1

An option calculator will get the correct volatility. For example, using the calculator at

http://www.mdwoptions.com/OptionCalculator.html

if you fill in

How much is the option price? (in $.c)
How much is the stock price? (in $.c)
What is the strike price? (in $.c)
What is the dividend yield? (in percentages per annum)
What is the interest rate? (in percentages per annum)
Time left to expiration?

and leave

What is the volatility? (in percentages per annum)

blank, then hit the "compute" button beside the space for the volatility, it will calculate the volatility for you.