Margin Trading Calculator
Calculate buying power, margin requirements, and interest costs for margin trading. Enter values for instant results with step-by-step formulas.
Reviewed by Sahil, Senior Finance & Tax Editor
Formula
Buying Power = Equity / Margin Rate | Margin Call Price = Borrowed / (Shares x (1 - Maintenance%))
Buying power is your equity divided by the initial margin requirement. The margin call price is determined by finding the stock price at which your account equity equals the maintenance margin percentage of the total position value.
Worked Examples
Example 1: Long Margin Trade with Profit
Problem:You have $25,000 equity and buy 200 shares at $100 (50% margin). The interest rate is 8%. After 1 year, you sell at $120 per share.
Solution:Total position = 200 x $100 = $20,000\nBorrowed = $20,000 - $25,000 = $0 (fully covered by equity)\nActually, with 200 shares at $100 = $20,000 total. Equity covers it.\nLet us use 400 shares: Position = $40,000, Borrowed = $15,000\nInterest = $15,000 x 8% = $1,200\nExit value = 400 x $120 = $48,000\nGross P/L = $48,000 - $40,000 = $8,000\nNet P/L = $8,000 - $1,200 = $6,800\nReturn on equity = $6,800 / $25,000 = 27.2%
Result:Net Profit: $6,800 | Return on Equity: 27.2% vs 20% without margin
Example 2: Margin Call Scenario
Problem:You have $25,000 equity, buy 500 shares at $100 ($50,000 position, 50% margin). At what price does a margin call occur (25% maintenance)?
Solution:Borrowed amount = $50,000 - $25,000 = $25,000\nMaintenance margin = 25%\nMargin call when: (Position Value - Borrowed) / Position Value = 25%\n500P - 25,000 = 0.25 x 500P\n500P - 25,000 = 125P\n375P = 25,000\nP = $66.67\nAt $66.67: Position = $33,335, Equity = $8,335 (25%)
Result:Margin call at $66.67 per share (33.3% decline from purchase)
Frequently Asked Questions
What is a margin call and when does it happen?
A margin call occurs when the equity in your margin account falls below the minimum maintenance margin required by your broker, typically 25% as mandated by FINRA, though many brokers require 30-40%. When triggered, you must deposit additional funds or securities, or sell existing holdings to restore your equity above the minimum threshold. Brokers can issue margin calls at any time and may liquidate your positions without notice if you fail to meet the call promptly. For example, if you bought $50,000 of stock with $25,000 equity and the stock drops to $33,333, your equity falls to $8,333 (25% of position value), triggering a margin call. Margin calls often happen at the worst possible time during market downturns, forcing you to sell at depressed prices.
How is margin interest calculated?
Margin interest is calculated daily based on the outstanding margin loan balance and the applicable interest rate, then typically charged monthly. The formula is: Daily Interest = Loan Balance x Annual Rate / 360 (most brokers use a 360-day year). Interest rates vary by broker and loan size, ranging from about 5% for large balances at discount brokers to 13% or more at full-service brokers. Some brokers use tiered rates where larger loan balances receive lower rates. Interest accrues from the settlement date of the margin purchase, not the trade date. Over time, margin interest can significantly erode returns, especially in sideways or slowly appreciating markets. Always factor in the total interest cost over your expected holding period when evaluating whether a margin trade is worthwhile.
What is the difference between initial margin and maintenance margin?
Initial margin is the minimum equity percentage you must have to open a new margin position, set at 50% by Federal Reserve Regulation T for most stocks. This means you can borrow up to 50% of the purchase price of a security. Maintenance margin is the minimum equity percentage you must maintain after the position is opened, with FINRA setting the floor at 25%, though most brokers require 30-40%. If your equity drops below the maintenance margin due to price declines, you receive a margin call. The gap between initial and maintenance margin provides a buffer, allowing the stock to decline somewhat before triggering a call. For volatile stocks, penny stocks, or concentrated positions, brokers may impose higher initial and maintenance requirements, sometimes up to 100% (effectively eliminating margin).
What types of securities can be purchased on margin?
Most listed stocks trading above $3 per share on major exchanges like NYSE and NASDAQ are eligible for margin trading, though individual brokers may restrict specific securities. Exchange-traded funds (ETFs) are generally marginable, including leveraged ETFs although brokers often require higher margin for these. Most bonds, including corporate and government bonds, can be purchased on margin with varying requirements. However, several security types are typically not marginable: stocks priced under $5 per share (penny stocks), initial public offerings for the first 30 days, options contracts themselves (though options can be used to satisfy margin requirements), and mutual funds within the first 30 days of purchase. Cryptocurrency margin trading is available on specific crypto exchanges but is not offered through traditional stock brokerages in the same manner.
References
Reviewed by Sahil, Senior Finance & Tax Editor · Editorial policy