Day traders generally use margin leverage; in the United States, Regulation T permits an initial maximum leverage of 2:1, but many brokers will permit 4:1 leverage as long as the leverage is reduced to 2:1 or less by the end of the trading day. In the United States, people who make more than 4 day trades per week are termed pattern day traders and are required to maintain $25,000 in equity in their accounts. Since margin interest is typically only charged on overnight balances, the trader may pay no interest fees for the margin benefit, though still running the risk of a margin call. Margin interest rates are usually based on the broker's call.
When you start day trading you’ll have a host of difficult decisions to make. Should you be using Robinhood? What about day trading on Coinbase? Do you have the right desk setup? Where can you find an excel template? How do you set up a watch list? The meaning of all these questions and much more is explained in detail across the comprehensive pages on this website.
Commissions for direct-access brokers are calculated based on volume. The more shares traded, the cheaper the commission. The average commission per trade is roughly $5 per round trip (getting in and out of a position). While a retail broker might charge $7 or more per trade regardless of the trade size, a typical direct-access broker may charge anywhere from $0.01 to $0.0002 per share traded (from $10 down to $.20 per 1000 shares), or $0.25 per futures contract. A scalper can cover such costs with even a minimal gain.
Assess how much capital you're willing to risk on each trade. Many successful day traders risk less than 1% to 2% of their account per trade. If you have a $40,000 trading account and are willing to risk 0.5% of your capital on each trade, your maximum loss per trade is $200 (0.005 x $40,000). Set aside a surplus amount of funds you can trade with and you're prepared to lose. Remember, it may or may not happen.