A day trade is the purchase and sale of the same security on the same day.
Cash Account
In a cash account, day trades will not be counted. There is no limit to make day trades with your settled funds. However, trades placed in a cash account require 1 business day for the funds to fully settle before they can be used to buy and sell again (trade date plus 1 business day). Good-faith violations occur when the purchase of a security uses funds that have yet to settle in the account. If you make day trades with a cash account while you do not have enough settled funds, you may receive good-faith violations (GFVs).
Margin Account
According to regulatory rules, ordinary investors can make at most 3 day trades within 5 business days. If you want to make more day trades, please keep the account balance no less than $25,000.
As a PDT, you must maintain a minimum equity of $25,000 to be eligible for unlimited day trades.