Your buying power is the amount of funds you have available to purchase securities. Your account value will be higher than your buying power after you sell securities or transfer money into your account.
Buying Power cushion for market orders
The default order type is Market. If you choose to use Market, you must have buying power equal to at least 1.1x the price of the security for the app to accept the order. This cushion may help any increase in the price, due to a sudden market move, upon placing your order.
For example, if an option is trading at $100 per contract, you would need $110 available in Buying Power to enter a market order.