Margin Call Calculator
Calculate at what price a margin call is triggered on a leveraged stock position.
What this calculator does
This calculator answers a question every margin borrower should know the answer to before placing the trade: how far can this position fall before my broker forces me out of it? The formula is purchase price times one minus initial margin, divided by one minus maintenance margin.
It converts two abstract percentages — the initial margin you posted and the maintenance level your broker enforces — into a concrete price. Above that price you are fine. At or below it, you receive a demand for more cash, and if you cannot meet it, the position is liquidated at whatever the market is paying.
When to use it
Run it before opening any margin position, not after. Knowing the trigger price in advance turns leverage from a vague feeling of risk into a specific number you can compare against the stock's actual volatility and against how much cash you could raise in a hurry.
It is also worth running whenever your broker changes its house maintenance requirement, which they do without much notice on volatile names, and after any large price move. A position that was comfortably clear of its call price in January may be far closer to it now.
Understanding the inputs
Purchase price is what you paid per share for the leveraged position. Initial margin is the percentage of the purchase you funded with your own money — Regulation T caps borrowing at 50 percent, so this is at least 50 percent for a standard stock purchase.
Maintenance margin is the minimum equity percentage your broker requires you to keep. FINRA sets the floor at 25 percent, but most brokers apply 30 to 40 percent, and often much higher on concentrated, low-priced, or highly volatile holdings. Use the number in your own margin agreement, not the regulatory minimum.
How is this calculated?
Margin Call Price = Purchase Price × (1 − Initial Margin) / (1 − Maintenance Margin).
A worked example
You buy 500 shares at $80, a $40,000 position, funding half with cash and borrowing $20,000 under Reg T. Your broker's maintenance requirement is 30 percent. The call price is $80 times 0.50 divided by 0.70, which is $57.14.
That is a 28.6 percent decline — well within a normal drawdown for an individual stock. At that price the position is worth $28,570, your equity is $8,570, and you are at exactly 30 percent. One tick lower and the call arrives. Had your broker used the 25 percent minimum, the trigger would sit at $53.33 instead.
Limitations and assumptions
Buying on margin is leveraged investing, and losses can exceed the money you put in. If a stock gaps down overnight through your call price, liquidation may occur far below the trigger, leaving you owing the broker a debit balance. This is a materially different risk from an unleveraged position, which can at worst fall to zero.
The calculation excludes accrued margin interest, dividends, house requirement changes, and the effect of other holdings in a cross-margined account. Past returns do not predict future ones, and the model assumes a flat return with no volatility. This is not investment advice — margin is unsuitable for most investors.
Common Questions
- What is a margin call?
- A demand from your broker to deposit more cash or securities because the equity in your account has fallen below the maintenance requirement. You typically get a short window — often two to five business days, sometimes less — to meet it. If you do not, the broker sells your positions, at prices you do not choose.
- At what price does a margin call happen?
- Margin call price equals purchase price times one minus the initial margin, divided by one minus the maintenance margin. Buying at $80 with 50 percent initial margin and a 30 percent maintenance requirement triggers a call at $57.14 — a fall of just 28.6 percent wipes out enough equity to breach the threshold.
- What is Regulation T?
- The Federal Reserve rule limiting initial margin on securities purchases to 50 percent, meaning you can borrow at most half the purchase price. Maintenance requirements are set separately by FINRA at a 25 percent minimum, though most brokers impose 30 to 40 percent, and considerably more on volatile or concentrated positions.
- Can I lose more than I invested?
- Yes. This is the defining risk of margin. Your losses are calculated on the full position value, not on your own contribution, while the loan must be repaid in full regardless. A sharp gap down through your call price can leave you owing the broker money after your entire equity is gone.
- Does the broker have to warn me before selling?
- No. Margin agreements explicitly permit brokers to liquidate positions without prior notice, choose which holdings to sell, and do so at whatever price the market offers. In fast-moving markets, forced liquidation frequently happens at or near the worst prices of the session.
- What is a house call versus an exchange call?
- An exchange call arises from breaching the FINRA 25 percent minimum. A house call arises from breaching your broker's own stricter requirement, which is usually 30 percent or higher. House calls are far more common, and brokers can raise house requirements at any time, including on positions you already hold.
- How do I calculate my current equity percentage?
- Divide your equity by the market value of the position. If you hold $100,000 of stock against a $40,000 margin loan, equity is $60,000 and your ratio is 60 percent. Watch this figure rather than the stock price — it is what actually determines whether a call arrives.
- What is the cheapest way to meet a margin call?
- Depositing cash preserves the position and immediately restores equity. Selling securities also works but crystallizes losses and may trigger a taxable event. Depositing fully paid marginable securities is a third route. Doing nothing is the worst option, because the broker's liquidation choices will not be optimized for your tax position.
- How does margin interest affect the math?
- It grinds against you continuously. Margin rates commonly run several percentage points above the benchmark and are charged daily on the borrowed balance. At 9 percent on a $40,000 loan, that is $3,600 a year the position must earn before you are even flat — a hurdle the price target above does not include.
- Is margin ever a reasonable tool?
- For short-term liquidity against a diversified portfolio, at low utilization, with a plan for a 40 percent market decline, some investors use it deliberately. As a way to increase exposure to a concentrated position, it converts an ordinary drawdown into a permanent, forced loss. The distinction is discipline, not leverage itself.