Margin Requirement Calculator (Reg T + Maintenance)
Margin requirement calculator. Reg T initial margin (50%), FINRA maintenance margin (25% long; 30% or $5 a share short), the $2,000 minimum, buying power and the margin-call price. For long and short stock positions.
Margin Requirement Calculator
How to use the margin requirement calculator
Choose long or short
Long: buying stock with margin. Initial margin 50% per Reg T means you pay 50% cash and the broker lends 50%. Short: borrowing stock to sell. Initial margin still 50% — you must deposit 50% of the short position value to cover the borrowed stock's rise risk.
Enter stock price + shares
Current market price and the number of shares you're trading. Position value = price × shares. For Reg T initial margin: position value × 50% is the cash you need. Note that FINRA's old pattern-day-trader rule (the $25,000 minimum) is being replaced by intraday-margin standards under Regulatory Notice 26-10, effective 4 June 2026 with a phase-in to October 2027.
Adjust margin % if needed
Default: Reg T 50% initial / 25% maintenance for long. Brokers can impose higher requirements (called "house margin") for volatile, low-priced or thinly traded stocks. FINRA itself sets a higher floor for short positions: 30% of market value or $5 a share, whichever is greater, for stocks at $5 or more, and $2.50 a share or 100% for stocks under $5. With Apply US minimums ticked, a rate below Regulation T's 50% or FINRA's 25% / 30% is raised to it and the page says so; untick it for a market with its own rules. Check your broker's margin requirement screen for the actual %.
Enter cash available
Used to compute buying power (2× cash at 50% initial) and the most shares you could open. FINRA Rule 4210(b) also requires equity of at least $2,000 before you borrow — or the full cost, if the purchase is smaller — so under US rules cash below $2,000 buys outright and cannot open a short. Using all of your buying power leaves no room for an adverse move before a call.
Read margin call price
Critical number. For long positions: the price the stock can fall to before your equity drops below maintenance %. For shorts: the price the stock can rise to. Beyond it, the broker will demand additional equity within whatever period its margin agreement allows — or liquidate the position, which the agreement usually permits without notice. The "cushion %" shows how much of a move you can absorb.
Margin — how brokers lend you money to amplify trades
Margin in stock trading is essentially a loan from your broker, secured by the securities in your account. Regulation T — the Federal Reserve Board rule on credit by brokers and dealers — requires initial margin of 50% of the current market value of a margin equity security (12 CFR 220.12). Translation: with $10K of your own cash, you can control $20K of stocks. FINRA Rule 4210(c) sets maintenance margin (the floor you must maintain) at 25% of market value for long positions and, for short positions, 30% or $5 a share, whichever is greater, on stocks at $5 or more, and the greater of 100% or $2.50 a share below $5. FINRA Rule 4210(b) adds a minimum: equity of at least $2,000, or the full cost of a smaller purchase. The SEC notes that many firms set their maintenance requirement higher than 25%. The calculator applies all of these floors when Apply US minimums is ticked. The calculator above shows you the exact margin needed, the loan amount you'll carry, and — most importantly — the margin-call trigger price.
Why margin matters even if you don't use it
Many brokers open a margin account unless you ask for a cash account. Even if you never intend to borrow, understanding margin matters because: (1) Settlement timing — US equities settle T+1 (since May 2024), and buying with unsettled proceeds in a cash account can trigger a free-riding violation. (2) Intraday margin — FINRA's pattern-day-trader rule ($25,000 minimum equity, four day-trades in five days) is being replaced by intraday-margin standards under Regulatory Notice 26-10, effective 4 June 2026 with a phase-in to 20 October 2027; check which regime your broker applies. (3) Margin call risk — the SEC warns that a broker may not be required to make a margin call at all, and may be able to sell your securities at any time without consulting you first. Every retail trader should understand the calculator above before clicking "buy".
The loan does not shrink when the shares fall — only your equity does. That is why the call price, not the deposit, is the number to know before you buy.
Margin costs — the silent return killer
Margin loans are NOT free. Brokers charge interest on the borrowed portion at a rate they publish, usually a spread over a benchmark rate that falls as the loan grows; the range between brokers is wide, so check the schedule before you borrow. The note beneath the result assumes 10% a year purely for illustration. Margin interest is a real drag on returns. Borrowing $50K at an illustrative 10% costs $5K a year, so the borrowed half of the position has to earn more than 10% before leverage adds anything. For long-term investors, margin is rarely worth the cost.
Outside the US
The 50% / 25% / 30% figures and the $2,000 minimum above are US rules. Every other market sets its own initial and maintenance margins through its exchange, clearing house and broker agreements, and contracts-for-difference platforms apply different (usually much higher) leverage under their own regulators. Untick Apply US minimums, enter the initial and maintenance percentages your broker actually applies, and the margin-call arithmetic is the same.
Reg T lends you half; FINRA calls the loan when equity falls to a quarter
Regulation T (12 CFR 220.12): initial margin is 50% of a margin equity security's market value, and 150% for a short sale (100% proceeds plus 50%).
FINRA Rule 4210(c): maintenance margin is 25% of market value for long stock; for short stock it is the greater of 30% or $5 a share ($2.50 a share or 100% below $5).
House margin: brokers can require MORE than Reg T (volatile stocks, low-priced stocks, recent IPOs).
Margin call: the broker demands more equity within the period its margin agreement allows, or liquidates. Forced liquidation often happens at the worst time.
Buying power = cash / initial margin %. $10K cash → $20K buying power at Reg T 50%.
FINRA's pattern-day-trader rule ($25,000 minimum, four day trades in five days) is being replaced by intraday-margin standards — Regulatory Notice 26-10, effective 4 June 2026, phase-in to October 2027.
Margin interest is set by each broker as a spread over a benchmark rate and published on its site — the 10% used in the note above is an illustration, not a quote.
Short selling requires margin. Even cash accounts can't short — you need a margin account.
Portfolio margin (FINRA Rule 4210(g)) sets requirements from portfolio-level stress tests instead of fixed percentages — usually far lower for hedged positions, subject to minimum-equity and approval requirements.
$2,000 minimum equity (FINRA Rule 4210(b)): before borrowing you need $2,000 in the account — or the full purchase price, if that is less.
Frequently asked questions
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Three options. (1) Deposit cash or securities within the period your margin agreement allows to restore minimum equity. (2) Sell positions to reduce your loan, restoring the maintenance ratio. (3) Do nothing — your broker will liquidate positions at THEIR discretion, often at adverse prices, often without warning. Most margin agreements let the broker do this without prior notice. Don't get into a margin call situation — keep the cushion comfortable.
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Three reasons. (1) Risk-based pricing — retail margin loans have higher default risk than mortgages because the collateral (stocks) can drop 30%+ overnight. (2) Operational cost — brokers manage daily mark-to-market, margin calls, and forced liquidations. (3) Profit centre — margin lending is a significant revenue line for brokers, and the spread over their own funding cost varies widely from one broker to the next. Compare published margin-rate schedules before choosing where to borrow.
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For options strategies + hedged portfolios: very much yes. Portfolio margin (PM) calculates margin based on the entire portfolio's risk under stress scenarios (typically ±15% stock moves with parallel IV moves). A hedged position that requires the full spread width under strategy-based margin can require far less under PM. It is subject to FINRA Rule 4210(g) minimum-equity requirements and to broker approval, and brokers commonly set their own higher minimums. For simple long-stock accounts PM offers little benefit; for hedged, options-heavy accounts it can free up a large share of buying power.
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Yes. Brokers can raise house margin requirements at any time — typically for newly volatile names, pre-earnings, or in response to corporate events — and a requirement raised to 100% removes leverage on that stock entirely. FINRA Rule 4210(d) requires firms to have procedures for setting their own, higher requirements. Brokers generally need not give advance notice — check your account regularly during stress periods. For more stable accounts (large diversified equities, blue-chip ETFs), margin requirements rarely change.
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Yes — three reasons. (1) Higher maintenance margin (30% vs 25% long). (2) Borrow fees for hard-to-borrow stocks (HTB list). Heavily-shorted stocks can carry very high annualised borrow fees. (3) Dividends — the short seller must pay any dividends the underlying pays out, reducing returns. Add it up: shorting can cost materially more per year than going long the same dollar amount. This is why successful short sellers tend to focus on either short-term gambles (binary catalysts) or fundamentally broken structural shorts (frauds, dying businesses).
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Regulation T is a Federal Reserve Board rule (12 CFR Part 220) created by the Securities Exchange Act of 1934. It governs the extension of credit by brokers and dealers for securities transactions. The headline rule: initial margin on US equities is 50% of purchase value. Reg T also covers cash account settlement rules, free-riding, and various securities-lending mechanics. For a short sale it requires 150% — the sale proceeds plus 50% — under 12 CFR 220.12(c).
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No — this is for STOCK margin only. Options margin is more complex: Long options require 100% cash (no margin). Cash-secured puts require 100% of the strike × 100 in cash. Naked short options are margined under FINRA Rule 4210(f)(2) — broadly, the premium plus 20% of the underlying value, less any out-of-the-money amount, subject to a minimum. Defined-risk spreads are margined at the difference between the strikes. For options margin, use your broker's position-specific margin calculator. Our iron condor calculator shows the approximate Reg T margin for a 4-leg iron condor.
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Because this is the single most important number for any leveraged position. The math: for a long position, margin call triggers when equity / market value drops below maintenance %. As the stock falls, your loan stays constant (you owe what you borrowed) but the collateral shrinks, so the equity ratio collapses. Knowing this trigger price BEFORE you open the position is the difference between informed risk-taking and getting blown out. Set a stop-loss above the margin call price to avoid forced liquidation — manage your position before the broker has to.
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No. Position type, price, shares, cash — every input stays in your browser. Margin computations run entirely client-side. Open DevTools → Network when you click Calculate and you'll see zero outbound requests.
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Federal Reserve Regulation T — 12 CFR Part 220, the source document. FINRA Rule 4210 — maintenance margin requirements. SEC, "Margin: Borrowing Money to Pay for Stocks" (sec.gov/investor/pubs/margin.htm) — plain-English guide with a worked maintenance example. FINRA Regulatory Notice 26-10 — the 2026 replacement of the pattern-day-trader rule with intraday-margin standards. Your own broker's margin disclosure statement is the binding document for house requirements and interest rates.
Method & sources
How it computes
In integer cents. Long: deposit = max(initial %, maintenance %, FINRA $2,000 capped at cost) of value; loan = value − deposit; call price = loan ÷ (shares × (1 − maintenance)). Short: deposit = max(initial %, FINRA requirement, $2,000); call price = highest P with credit − shares × P ≥ requirement(P), requirement 30% or $5/share at $5+, 100% or $2.50/share below. US floors (50%, 25%, 30%) optional. RecaInvest.marginPosition.
What this tool implements
- Regulation T, 12 CFR 220.12: initial margin 50% of a margin equity security's current market value; a short sale 150% (the proceeds plus 50%).
- FINRA Rule 4210(b)(4): equity of at least $2,000, except that cash need not be deposited in excess of the cost of the security purchased. Under US rules a long below $2,000 of cash is bought outright, and a short cannot be opened.
- FINRA Rule 4210(c): maintenance 25% of market value for long stock; for short stock the greater of $5.00 a share or 30% at $5.00 and above, and the greater of $2.50 a share or 100% below $5.00. The short margin-call price solves the requirement across that boundary, so a short under $5 is at its call from the moment it is opened.
- Rates the reader enters below the US floors are raised to them and the page says so; rates above are used as entered (house margin). With "Apply US minimums" off the percentages are used as entered and nothing else applies, for markets with their own rules.
- Checked against the SEC's worked example ("Margin: Borrowing Money to Pay for Stocks"): $16,000 bought with an $8,000 loan, falling to $12,000, meets a 25% requirement and is $800 short of a 40% one.
- Money in integer cents: deposit + loan equals the position value exactly. The interest note uses an illustrative 10% and only for a long; a short pays borrow fees and dividends instead.
Sources
- Board of Governors of the Federal Reserve System. Regulation T, 12 CFR §220.12 Supplement: margin requirements: https://www.law.cornell.edu/cfr/text/12/220.12
- FINRA Rule 4210, Margin Requirements — (b) initial margin, (c) maintenance margin, (g) portfolio margin: https://www.finra.org/rules-guidance/rulebooks/finra-rules/4210
- FINRA Regulatory Notice 26-10, intraday margin standards replacing the day-trading margin requirements (effective 4 June 2026; phase-in ends 20 October 2027): https://www.finra.org/rules-guidance/notices/26-10
- U.S. Securities and Exchange Commission. Margin: Borrowing Money to Pay for Stocks: https://www.sec.gov/investor/pubs/margin.htm
- U.S. Securities and Exchange Commission. Press release 2023-29 — T+1 settlement, compliance date 28 May 2024: https://www.sec.gov/newsroom/press-releases/2023-29
What can make this go out of date
- FINRA Rule 4210 amendments (Notice 26-10 phase-in through 20 Oct 2027); broker house margin and margin interest rates are per broker and not modelled.
Abridged — the full review record for this tool runs longer than the list above.
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