Zerodha Margins for Options

I have an available balance of 26215, out of which 8865 is of cash, the rest being pledged amount.
Can someone help me by clarifying, What is the amount which I can use for intraday trading?
I was not able to buy call options worth 22K.
Thank you.

The margin received from pledging i.e collateral margin can be used for trading Equity Intraday, Futures long & short & Options writing.

You will not be able to use this margin to buy options. for more info click here.