Your buying power is the total amount of funds that you can use to trade for that particular day. The account balance in your trading account is the opening balance of today’s ledger. 

The utilized margin is:

1. The amount blocked for your open orders that are not yet executed.
2. The net funds utilized for your executed equity, intraday and delivery orders, F&O and CDS positional/intraday trading orders.
3. Any M2M realized or unrealized loss of the day on equity intraday, F&O and CDS positions. Whenever you square off your positions, the utilized margin will be credited back to your buying power.