A margin requirement is the equity a broker or clearing house demands before you can hold a position. Enter the price, quantity, contract multiplier and margin rates below and the calculator returns the notional value the position controls, the cash it ties up, the effective leverage that implies, and the price at which a maintenance call is triggered.
Margin requirement calculator
Selecting a market loads typical inputs so you can see the shape of each one. They are illustrative defaults, not live requirements — your broker and, for futures, the exchange set the real numbers, and they change. Educational tool, not advice.
The formulas behind the four boxes
All four outputs come from three multiplications and one division. Notional value is what the position controls. Initial margin is what it costs you to control it. Leverage is the ratio between them.
Initial margin: Notional × initial rate
Leverage: Notional ÷ Initial margin
Long call price: Entry × (1 − initial rate) ÷ (1 − maintenance rate)
The last line is the one worth memorising. It says that the distance between your entry and a maintenance call depends only on the two margin rates, not on the size of the position. At a 50% initial rate and a 25% maintenance rate, the trigger sits exactly one third below the entry, whether you bought 20 shares or 20,000.
Margin means three different things in three markets
Traders move between markets and carry the wrong mental model with them. These are genuinely different mechanisms that happen to share a word.
| US stocks | Futures | Retail forex | |
|---|---|---|---|
| What margin is | A loan from the broker | A performance bond | Collateral against a leveraged position |
| Who sets it | Regulation T, FINRA, plus house rules | The exchange and clearing house | The broker, within regulatory leverage caps |
| Interest charged | Yes, on the borrowed portion | No, nothing is borrowed | Via overnight swap rather than margin interest |
| Quoted as | A percentage of position value | A dollar amount per contract | A percentage, or as a leverage ratio |
| Changes when | The firm revises house requirements | Volatility rises — often at short notice | Around events, or by regulation |
Stocks: Regulation T and the 25% floor
A standard US margin account lets you buy roughly twice your equity, and FINRA requires that equity stay at or above 25% of the current market value of long margin-eligible securities, maintained throughout the trading day, with a minimum of $2,000 to trade on margin at all (FINRA, intraday margin requirements). The intraday standard took effect on June 4, 2026, with firms allowed a transition through October 20, 2027, and it replaced the old pattern day trader framework and its $25,000 minimum. Failing repeatedly to meet an intraday deficit can restrict an account for up to 90 days. What changed and what did not is set out in the pattern day trader rule in 2026.
Futures: a performance bond, not a down payment
Futures margin is a good-faith deposit the clearing house requires from both sides so each can cover a day of adverse movement, calculated portfolio-wide by a risk model rather than as a flat percentage — the CFTC's technical description of the SPAN methodology sets out how those scenarios are built (CFTC, standard portfolio analysis of risk). Because it is quoted per contract in dollars, you convert it to a percentage by dividing by notional. E-mini S&P 500 futures carry a multiplier of $50 per index point (CME Group contract specifications), so at an index level of 5,500 one contract represents $275,000 of notional exposure. If your broker quotes $18,000 of initial margin on that contract, the requirement is 6.5% of notional and the leverage is about 15 to 1. Check the current figure before you rely on it — exchange margins are reset regularly, and the mechanics are covered in futures margin explained.
Forex: the same number wearing a leverage ratio
Retail forex brokers usually quote leverage instead of margin, and the two are reciprocals: 50:1 leverage is a 2% margin requirement, 30:1 is 3.33%, 20:1 is 5%. A standard lot is 100,000 units of the base currency, so a single lot of a pair trading at 1.0850 is $108,500 of notional and needs $2,170 at 2%. The caps differ sharply by jurisdiction, so confirm the rules that apply where your account is held.
Why the margin number is not a risk number
This is the most expensive misunderstanding in the tool above. Margin tells you what a position costs to open. It says nothing about what it can lose, and the two are unrelated for anything leveraged. A futures position requiring $18,000 can lose far more than $18,000 in a fast market, because the loss is a function of the notional value, not of the deposit.
- Size from the stop, not from the requirement. The correct question is how many units make your stop distance equal your risk budget — the arithmetic is in position sizing from risk and the position size calculator.
- Maximum affordable size is a trap. "The account allows six contracts" is a statement about margin. It is never a statement about how many you should hold.
- Requirements move against you at the worst time. Exchanges raise margin when volatility spikes, which is exactly when open positions are already under pressure.
- A call is not the same as a loss limit. By the time the call arrives you are usually already deep into the territory mapped by the drawdown recovery calculator.
The relationship between margin, leverage and the size of a loss is unpacked in what leverage in trading really is, and what happens when the requirement is breached is in what a margin call is and how to avoid one.
Frequently Asked Questions
How do you calculate a margin requirement?
Multiply the price by the quantity and by the contract multiplier to get the notional value, then multiply that notional value by the initial margin percentage. Two hundred shares at 50 dollars is 10,000 dollars of notional, and at a 50 percent initial requirement the position ties up 5,000 dollars of your own equity. Futures margin is usually quoted as a fixed dollar amount per contract instead, which you can convert to a percentage by dividing it by the notional value.
What is the maintenance margin requirement in the US?
FINRA requires equity of at least 25 percent of the current market value of long margin-eligible equity securities, maintained throughout the trading day, and a minimum of 2,000 dollars in equity to trade on margin at all. Brokerage firms are free to set stricter house requirements, and many do on volatile or low-priced stocks.
At what price do you get a margin call?
For a long position, the maintenance call price is the entry price multiplied by one minus the initial margin rate, divided by one minus the maintenance margin rate. A stock bought at 100 dollars with 50 percent initial margin and a 25 percent maintenance requirement triggers at about 66.67 dollars, which is a fall of one third. Raising the initial margin you post moves that trigger further away.
Is futures margin the same as stock margin?
No. Stock margin is a loan from the broker, and you pay interest on the borrowed portion. Futures margin is a performance bond: a good-faith deposit set by the exchange and clearing house so both sides of the contract can cover a day of adverse movement. No money is borrowed, nothing is lent, and the requirement can be raised by the exchange at short notice when volatility rises.
Bottom line
Use the calculator to answer two questions before a trade, and only two: what does this position actually control, and how far can price travel before somebody else starts making decisions for me. Then put the number away and size the trade from your stop instead. Margin sets the ceiling on what is possible; risk management in trading sets the floor under what survives.