In order to calculate capital, the first step will be determining a cost of acquisition and period of holding.

As per the income tax act, if the person receiving the capital asset by way of gift, will, etc. subsequently transfers such asset, capital gain will arise.
In such a case, the cost of acquisition of the capital asset will be the cost of acquisition to the previous owner and the period of holding of the capital asset will be computed from the date of acquisition of the capital asset by the previous owner.

Since you received the house property as a gift, cost of acquisition shall be the purchase/construction cost incurred to that house property by your father and period of holding shall be accounted from the date of acquisition from your father.

Further, if the sale of capital assets results in short-term capital gain then you have to pay 15% tax on gain.

If your sale constitutes a long-term capital gain in the following manner.

Sale price XX
Indexed cost of acquisition (XX)
Indexed cost of improvement (XX)
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Gain or (loss) XXX