Futures Margin Explained: Initial, Maintenance and Why It Is Not Your Risk

Margin is the most misunderstood number in futures. It is not the cost of the trade, not the most you can lose, and not a percentage of anything. It is a performance bond that says "post this much so we know you can settle".

The three numbers

	Initial margin	Maintenance margin	Your actual risk
What it is	The amount required to open a position	The minimum to keep it open	Stop distance × tick value × contracts
Who sets it	Exchange minimum, broker may add	Same	You do
Changes	Whenever the exchange revises it	Same	Only when you change your stop
Breach consequence	Cannot add exposure	Margin call — deposit or liquidate	You lose the money

The key misunderstanding: a $2,000 margin requirement does not mean your maximum loss is $2,000. It means the broker wants $2,000 posted. If the market gaps through your stop, you can lose more than the margin — that is the entire reason margin calls exist.

Why the same contract has different margin at different brokers

The exchange publishes a minimum. Brokers almost always require more, and the amount varies:

Exchange minimum — CME, ICE or Eurex publishes initial and maintenance per contract, revised periodically
Broker buffer — typically 110–150% of the exchange minimum, sized to the broker's own risk appetite
Day-trade margin — many brokers offer a reduced intraday requirement, sometimes a third of the overnight figure
Account type — a hedging account or a portfolio-margin account can be assessed very differently

This is why this site does not publish a margin table. A number without a date and a broker name is not information.

The intraday / overnight trap

A position that fits comfortably at 14:00 can trigger a call at settlement.

	Intraday	Overnight
Typical requirement	Reduced (sometimes 25–50%)	Full exchange margin
When it applies	During the session	Held past the broker's cut-off
Risk	None if you close	Gap risk is yours

If you hold ten contracts on intraday margin and the session closes with them still on, you may need to post the difference immediately or have positions liquidated at whatever price the market gives.

How to size a position (the only method that works)

Set the dollar risk. Usually 1–2% of account equity.
Measure the stop on the chart — in ticks, from a structural level, not from what you can afford.
Divide: contracts = risk ÷ (stop in ticks × tick value)
Check the margin only afterwards, to confirm the broker will let you hold it.

Worked example

Account $30,000. Risk 1.5% = $450. Stop on ES is 12 ticks.

12 × $12.50 = $150 per contract → $450 ÷ $150 = 3 contracts

Now check margin: if ES requires $2,500 per contract, three contracts post $7,500 — 25% of equity. That is fine. If it required $10,000 per contract, the margin would force you to two contracts even though your risk budget allowed three. The smaller of the two numbers wins.

Three mistakes worth knowing

1. Treating margin as buying power

Available margin is not a target. A $50,000 account with $5,000 ES margin can technically hold ten contracts. Risking ten contracts on a 12-tick stop is $1,500 — 3% of equity on one trade, and a losing streak of four would take 12%.

2. Ignoring that margin rises with volatility

Exchanges raise margin when volatility rises, which is exactly when you are holding a losing position. A position that was comfortable can require more money the day it goes against you.

3. Forgetting the maintenance floor

A call is triggered by equity falling below maintenance margin, not initial. The gap between the two is your buffer, and on a fast market it can disappear in minutes.

Use the margin calculator with your broker's live figure, and the specification table for tick values.

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