Yes, I can use the whole cash up to 2 times per day, but when using 2 times then I cannot close them on the same day. Example: Say you have $10,000 avail. Then you can do 10 round-trip trades of each $1,000, ie. 10x opening and 10x closing on the same day. And: you can additionally even open another 10 such trades, but these you cannot close on the same day (because these use "unsettled cash" from the previous sales). There is a settlement time of T+1 for options and T+2 for stocks, ie. you must wait that many days till your proceeds from the sales get settled. T+1 means just tomorrow at market opening the funds will be settled and can be used. If you do the maths, then you can do many daytrades. But study the settlement rules very good to avoid trading rule violations: https://www.fidelity.com/learning-center/trading-investing/trading/avoiding-cash-trading-violations