Trading on margin? Enter your cash, the margin requirements and the position you want to buy to see your buying power, the size of the loan, your equity, and how far prices can fall before a margin call.
Answer first: margin lets you buy more than your cash allows by borrowing from your broker. This margin calculator shows your buying power, how much of the position is your own equity versus a loan, and — critically — how far the position can fall before you get a margin call.
Buying power = Cash ÷ Initial-margin%. Loan = Position − Your cash. Margin-call value = Loan ÷ (1 − Maintenance%).
Example: $10,000 cash at 50% initial margin gives $20,000 buying power. Buy a $15,000 position and you borrow $5,000; your equity is 66.7%. With 25% maintenance margin, a margin call triggers once the position falls to $6,666.67 — a 55.6% drop.
The appeal is leverage: control a bigger position with the same cash, and gains on the whole position accrue to your smaller equity. The danger is the same lever in reverse — losses are magnified against your equity, you owe interest on the loan whether the trade wins or loses, and a sharp drop can force a sale at the worst possible time.
Brokers require your equity to stay above the maintenance margin (often 25–40%). If a falling position pushes your equity percentage below that line, you get a margin call: deposit more cash or the broker sells your holdings — sometimes automatically, sometimes at a loss you can't control. The "drop to call" figure above is your safety cushion before that happens.
Margin amplifies both outcomes, but losses hurt more than gains help because you can lose more than your original cash and still owe interest. Many experienced investors avoid margin entirely. If you're learning, the smart move is to understand the mechanics here and practice the feel of leverage with play money, never your real account.
Reality check: It uses simplified Reg-T-style assumptions and ignores broker-specific requirements, margin interest, special-margin securities and intraday rules. Trading on margin can cost you more than your initial investment. This is an educational calculator, not financial advice — verify your own numbers and see the U.S. SEC at investor.gov.
Understand the concept in what is margin trading and what is leverage in trading, then size positions safely with the position size calculator.
Last updated 21 June 2026 · Written by Mustafa Bilgic. Educational only — not financial advice.
Divide your cash by the initial margin requirement. At 50% initial margin, $10,000 of cash gives $20,000 of buying power, because the broker lends you up to an equal amount against your equity.
A margin call happens when your equity falls below the maintenance margin requirement, often 25%–40%. As the position drops, your loan stays fixed while your equity shrinks; once equity dips under the threshold you must add cash or assets are sold.
The position value at a margin call equals the loan divided by (1 minus the maintenance margin). At a $5,000 loan and 25% maintenance, the call hits when the position falls to $6,666.67. The calculator also shows the percentage drop that represents.
Yes. Leverage magnifies losses as well as gains, you pay interest on the loan regardless of the outcome, and a forced sale can lock in losses at the worst time. You can lose more than your original cash, so beginners should be very cautious.