Margin Requirements Are Inputs, Not Universal Constants
The calculator models leverage and an estimated margin-call threshold using the maintenance requirement you provide rather than assuming that every account uses one fixed percentage.
Broker house requirements can exceed regulatory minimums and can change by security or market conditions. Interest, forced liquidation rules and intraday requirements also vary by broker.
Leverage changes the relationship between the security's price move and the return on your own capital. If part of the position is borrowed, a 10% market move can produce a much larger percentage gain or loss on the cash you contributed. Interest on the borrowed balance also reduces returns over time. A margin-call estimate is therefore not a target price; it is a warning threshold based on the assumptions entered, and brokers can apply stricter house requirements than the regulatory minimum.
Frequently Asked Questions
Is 25% always the maintenance margin?
No. Regulatory minimums and broker house requirements are not the same thing, and a broker can require more than a minimum. Enter the requirement that applies to the position you are modeling.
Why can a modest stock decline create a much larger loss on my cash?
Because borrowed money increases the size of the position relative to your own equity. The market loss applies to the full position while your invested cash is only part of that total.
Methodology & Related Tools
Review how RatioCalc builds, tests and updates calculator models before using an estimate for a material decision.
Accuracy review
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Site-wide consistency review: September 4, 2026.