This margin calculator computes the required values based on standard Regulation T (Reg T) and broker maintenance margin formulas for long positions. It assumes you are buying stock.
The initial margin requirement is the percentage of the purchase price that you must pay with your own cash. Under Regulation T, the Federal Reserve Board sets this minimum at 50%, though some brokers may require more for volatile stocks.
Maintenance margin is the minimum equity you must keep in your margin account after the purchase has been made. FINRA requires a minimum of 25%, but many brokers require 30% to 40% depending on the asset's risk.
A margin call occurs when the value of your account equity falls below the broker's required maintenance margin. When this happens, you must either deposit more funds or sell off some of your assets to meet the minimum requirement.
Westmount Fundamentals. "Margin & Leverage Calculator." westmountfundamentals.com/margin-calculator, 2026.