Day trading buying power calculator
Pattern day traders in US margin accounts can trade up to four times their maintenance margin excess during the day, but only half of that overnight. Enter your equity at yesterday's close, the maintenance margin on positions you are holding and the stock you want to trade, and this calculator works out your day trading buying power and how many shares it buys. It also shows the overnight limit, so you know how much has to be closed before the bell.
Intraday vs overnight
Your equity, the excess that buying power is built on, and what you can hold during the day compared with overnight.
Shares you can trade by maintenance requirement
Brokers set higher requirements on riskier stocks. The higher the requirement, the fewer shares your buying power covers.
| Requirement on the stock | Intraday shares | Intraday value | Overnight shares |
|---|
How day trading buying power is worked out
This follows the standard FINRA margin rules for pattern day traders. Your broker can set stricter limits, so check its figures before trading at the edge.
Maintenance margin excess
Equity minus the maintenance required on positions held overnight.
excess = equity − held positions × their requirement
Day trading buying power
Up to four times the excess, for accounts at or above $25,000.
DTBP = 4 × excess
Adjust for the stock
Four times assumes a 25% requirement. A higher requirement buys proportionally less.
tradeable value = DTBP × 25% ÷ stock requirement
Shares
Tradeable value divided by the price, rounded down.
shares = tradeable value ÷ price
Overnight
Positions held past the close need 50% initial margin, so about twice the excess.
overnight buying power ≈ 2 × excess
Buying power questions
What is day trading buying power?
It is the amount a pattern day trader can buy and sell within a single day in a US margin account. Under FINRA rules it is up to four times the account's maintenance margin excess, measured at the previous day's close. It only applies to positions opened and closed the same day.
How is day trading buying power calculated?
Take your equity at yesterday's close and subtract the maintenance margin required on positions you held overnight. That is your maintenance margin excess. Multiply it by four. With $40,000 of equity and $6,000 of maintenance on overnight positions, the excess is $34,000 and buying power is $136,000.
Why can I buy fewer shares of some stocks?
Brokers set higher maintenance requirements on volatile, low-priced or concentrated positions, sometimes 50 percent or even 100 percent. A higher requirement means each dollar of buying power buys less of that stock. The calculator adjusts for the requirement you enter.
What is overnight buying power?
Positions held past the close fall under the standard initial margin of 50 percent, so overnight buying power is usually about twice your excess equity, not four times. Holding a full day trading position overnight can trigger a margin call.
What happens if I exceed my day trading buying power?
The broker issues a day trading margin call. Until it is met, usually within five business days, your buying power may be cut to two times excess, and failing to meet it can restrict the account to cash trades for 90 days.
Do accounts under $25,000 get day trading buying power?
No. Below $25,000, a margin account cannot be used for pattern day trading, so the four times figure does not apply. Our PDT rule calculator shows how many day trades you have left instead.