Margin on a futures contract isn’t a down payment or a fee — it’s a good-faith performance bond the exchange holds to guarantee you can cover a loss. Confuse it with your actual risk and you’ll size trades that look fine on the margin screen and still breach your drawdown.
Initial margin vs maintenance margin
Two numbers govern how much of an account a position ties up:
- Initial margin — the amount you must have available to open a contract. Set by the exchange clearing house and passed through (sometimes with a cushion) by your broker.
- Maintenance margin — the lower amount you must keep on the position. Drop below it and you get a margin call or an automatic liquidation.
On exchange-traded futures these are calculated with a published, portfolio-based risk model (the CME’s SPAN / SPAN 2 methodology). That matters for a structural reason: the same methodology applies to every participant, it’s centrally cleared, and the numbers are transparent and posted. Your initial margin on ES is derived the same way as everyone else’s — it isn’t a figure a dealer sets for you privately.
Day-trading margin is a broker number, not an exchange number
Here’s the distinction that trips up new futures traders. The exchange initial margin is the overnight requirement — what you need to carry a position through the close. But most futures brokers offer a much smaller intraday / day-trading margin for positions opened and closed inside the session.
That reduced day-trade margin is set by the broker, not the exchange. It’s a commercial decision, it varies from broker to broker, and it can be raised without much notice — commonly around major economic releases or when volatility spikes. If you build a strategy around a low day-trade margin and the broker doubles it before an NFP or FOMC print, positions you assumed you could open suddenly won’t fit.
| Initial (overnight) | Maintenance | Day-trading (intraday) | |
|---|---|---|---|
| Who sets it | Exchange clearing house | Exchange clearing house | Your broker |
| When it applies | To carry past the close | Continuously, while open | Only intraday, flat by close |
| Typical size | Full requirement | Slightly below initial | A fraction of initial |
| Changes when | Exchange revises SPAN | Exchange revises SPAN | Broker’s discretion / volatility |
Exact figures move constantly and differ by broker and contract, so confirm the current initial, maintenance and day-trade margins in your platform before you rely on them.
How funded accounts express limits — usually not as margin
On a prop evaluation you often won’t think in exchange margin at all. Funded futures programs typically translate risk into their own controls: a maximum contract count (how many ES or micros you may hold at once), a daily loss limit, and a trailing drawdown that ratchets up with your equity high-water mark. Those firm rules will bind long before exchange margin does.
That’s the part to plan around, because the firm’s line — not the clearing house’s — is what ends your account. The exact drawdown percentages, contract caps and loss limits vary by firm and program, so confirm them with the firm before you trade a single contract. Then model a realistic losing cluster against that line with the prop-firm drawdown calculator, and read up on how a trailing drawdown tightens as you go — it’s the rule that catches most funded traders off guard.
Margin tells you what you can open, not what you should
The most common margin mistake is treating available margin as a green light. Day-trade margin might let you open ten ES contracts; that says nothing about whether ten contracts fits your risk. Margin is a capacity limit. Your stop is the risk.
Size from the stop down, always:
- Decide the fixed dollars you’ll risk per trade — a small slice of the buffer.
- Read the point distance to where the idea is wrong.
- Solve for contracts using point value, and round down.
The futures contract calculator turns a stop distance into a contract count in micros or minis, so the position is sized by risk and merely checked against margin — never the other way around.
Confirm current requirements before you lean on them
Because both the exchange requirement and the broker’s intraday number can change — sometimes the same day — the safe habit is to check margins as part of your pre-session routine, especially before high-impact news. And remember that on a CFD account the “leverage” doing the same job is set entirely by the provider, whereas your futures initial margin comes from a transparent, centrally-cleared model. Same concept, very different governance.
Shibiki keeps the discipline honest either way: it can enforce a hard per-account risk limit at the broker, so a position that would exceed your planned per-trade dollars won’t send — no matter what your available margin happens to allow that minute.
Related: Prop-firm drawdown calculator · Futures contract calculator · Trailing drawdown