Stock Margin Calculator

How the Margin Calculator Works

This calculator helps stock traders understand the mechanics of margin trading — how much equity you need, when a margin call triggers, and what it costs to borrow from your broker.

Initial Margin Explained

When you buy stocks on margin, you must deposit a minimum percentage of the purchase price — this is the initial margin. Under Regulation T, the Federal Reserve requires at least 50% initial margin, meaning you can borrow up to half the position value. Some brokers require more for volatile stocks.

Maintenance Margin & Margin Calls

After you open a position, you must maintain a minimum equity level — the maintenance margin. FINRA requires at least 25%, but most brokers set it at 30–40%. If your stock drops enough that your equity falls below this threshold, your broker issues a margin call, requiring you to deposit more funds or sell holdings.

Margin Call Price Formula

The margin call trigger price is calculated as: Loan Amount ÷ (Shares × (1 − Maintenance %)). For example, with a $7,500 loan on 100 shares and 25% maintenance margin, the margin call price is $7,500 ÷ (100 × 0.75) = $100.00.

Interest & Break-Even

Margin loans carry interest, which eats into your returns. The break-even price is the stock price at which your gains exactly offset the interest cost. The longer you hold, the higher the break-even price.

Tips for Margin Trading

• Never invest more than you can afford to lose — leverage amplifies losses
• Keep a cash buffer above the maintenance requirement to avoid forced liquidation
• Monitor your equity percentage daily during volatile markets
• Compare margin rates across brokers — they vary significantly
• Consider the tax implications: margin interest may be deductible against investment income
• Use our ROI calculator to evaluate whether leveraged returns justify the risk
• Check your profit margins on trades after accounting for interest costs