What Is a Worked Example of Used Margin?

Used margin, defined

Used margin is the part of your account equity that a trading platform locks to support your currently open positions. Once a position is open, you typically cannot use the used margin to open new positions; that unavailable amount is reflected as reduced free margin.

A key idea is separation:

• Stable mechanics (conceptual): Used margin is tied to open exposure and the margin rule applied by the platform.
• Variable conditions (what can change): The exact margin rule can differ by provider and can be affected by contract specifications, leverage settings, and how costs are handled in the platform.

Because providers can use different formulas, a “worked example” is only meaningful when you state the assumptions clearly.

Mechanism for calculating used margin

A simple worked example usually needs these inputs:

1. Account currency (for reporting equity and margin).
2. Position size (often expressed in units, lots, or notional value).
3. Leverage or margin rate (the platform rule that determines how much margin is required).
4. Margin formula assumption (how the platform converts position size into used margin).

To keep the example self-contained, we assume a straightforward relationship:

• Assumption A: Used Margin = Notional Value ÷ Leverage.
• Assumption B: Notional Value is computed as Units × Price, with a fixed “entry price” used only for the example.
• Assumption C: We ignore mark-to-market changes for the moment we compute used margin, so equity is treated as stable except for the locked portion.

These assumptions are for illustration; real platforms may include contract multipliers and may treat costs differently.

Worked example with explicit numbers

Scenario: You have an account with equity in USD and you open one leveraged position.

Assumptions for this scenario (state everything):

• Assumption 1 (account equity): Equity at the moment after opening is $10,000.
• Assumption 2 (position exposure): You open 100,000 units of a currency pair.
• Assumption 3 (entry price for notional): Entry price is 1.2000 (quote currency per base unit).
• Assumption 4 (notional value): Notional = 100,000 × 1.2000 = 120,000 (in the quote currency, which we assume is USD-equivalent for simplicity).
• Assumption 5 (leverage): Platform leverage for this instrument is 20:1.
• Assumption 6 (margin rule): Used Margin = Notional ÷ Leverage.
• Assumption 7 (no other positions/costs considered): No other open trades and no commissions/spreads impact the margin figure in this simplified computation.

Step 1: Compute used margin

• Used Margin = 120,000 ÷ 20 = 6,000 USD.

Step 2: Compute free margin (conceptual)

• Free Margin = Equity − Used Margin = 10,000 − 6,000 = 4,000 USD.

What the numbers mean: After opening the trade under these assumptions, $6,000 is “allocated” to support the open position, and only $4,000 remains available to support additional positions.

Limitations and failure modes to understand

This example is intentionally simplified. Several material limitations can change real outcomes:

1. Provider-specific margin calculations

   • Your platform may use a margin rate that depends on instrument rules, contract size, or tiered leverage. That can make Used Margin differ from Notional ÷ Leverage.

2. Costs can affect equity and availability

   • Even if used margin is computed from notional, your equity can change due to fees, funding, or mark-to-market profit/loss. When equity drops, free margin drops too.

3. Market moves change equity and risk of margin pressure

   • As the trade value changes, unrealized gains/losses update equity. If equity falls far enough relative to required margin, the account may reach a critical level where the platform imposes restrictions.

4. Failure mode: opening additional trades while used margin is high

   • If free margin is already limited, attempts to open new positions may be rejected or may require smaller sizes because required margin increases with exposure.

5. Execution and specification differences

   • Spread, commissions, and order execution at different prices can alter the actual notional and resulting margin requirements compared with a simplified entry-price assumption.

These limitations do not contradict the concept; they explain why two platforms can show different used margin for the same apparent “leverage.”

How to verify used margin yourself

You can independently verify the logic by comparing the platform’s displayed used margin with a calculation using the platform’s own stated margin rules.