Hi
I had a look at your link. Here is the direct link to the calculation, as the download sheet is to complicated for non option traders.
http://www.option-price.com/index.php
You see four sheets : Option calculator / Custom Portfolio / Implied Volatility and Option combination.
To know, what is the right value of an option, you have to use the option calculator.
How to use ?
I will make a small introduction for those, which do not know it.
Underlying price : Here you put in actual price of the nifty like
Exercise price : Here you put in the strike price of the option you want to trade
Days until expiration : How many days are left, until your options expires ( or how many days you plan to keep this option. You then got an idea about, what the value tomorrow should be or how much you loose over the weekend with your option )
Interest rate : What are the official rates of the government bonds.
Dividend yield : Only useful, when you trade options on shares, as is the company's annual dividend payments divided by its market cap.
Volatility : Very, very important !! If the volatility in the market is high, the pricing of the option is very different compare to if the volatility is low.
Rounding : No use, at least for me.
Now let us make an example : Nifty is at 6260 / You want to buy a 6300 call /
this calls expires at the 20 of Nov ( as example ) / Government bond pays 5.25 % / Volatility in the market is around 35 %
Underlying : 6260 ( Nifty price at the moment )
Exercise price : 6300 ( 6300 call )
Days until expiration : 16 ( 20 - 4 = 16 )
Interest rate : 5 ( Government bond yields )
Dividend yield : 0
Volatility : 35 ( You must know, what volatility is in the market !! )
Rounding : 0
Now press Calculate.
You will see now on the right side : Theoretical price Call / Put
The call has a value of 171 and the put has a value of 197
Also watch the theta. That is what you lose per day.
Take care
DanPickUp