Futures cash buffer: how much to keep before a margin call
Build a practical futures cash-buffer calculation using notional exposure, adverse moves, margin requirements, and daily settlement
Direct answer
A futures cash buffer is the money left after opening margin that can absorb an adverse move, a higher requirement, and daily settlement. It is not a guarantee against a margin call, but it makes the liquidation threshold visible before entry.
Start with the loss the contract can create
Record contract count, multiplier, tick value, entry price, and futures notional value. Then convert two or three adverse price moves into dollars. A 2% scenario is a planning input, not a forecast.
Compare equity with the requirement that applies
Opening margin only answers whether the trade can start. Compare account equity with maintenance margin and review initial versus maintenance margin. Daily settlement can debit cash before a planned stop is reached; variation margin explains that path.
Use this worksheet:
| Line | Calculation | | --- | --- | | Adverse loss | price move × multiplier × contracts | | Requirement shock | new requirement − current requirement | | Operating reserve | fees, settlement timing, and unrelated withdrawals | | Cash buffer | adverse loss + requirement shock + reserve |
Separate exchange, clearing, and broker rules
The requirement shown in an account can be higher than the exchange minimum. An exchange may publish a baseline, a clearing firm may apply a risk add-on, and a broker may impose an overnight or concentration surcharge. Save the exact requirement for your account and contract, along with when it can change. Do not use a public margin table as proof that your available cash is sufficient.
Test the buffer before the order
If equity is $8,000, the opening requirement is $2,000, and a stress loss is $2,500, the remaining $5,500 is not automatically safe. Add a possible requirement increase, fees, and a gap beyond the stop. If the result would force a funding decision, reduce contracts or do not enter.
TryMark checkpoint: save the exact maintenance requirement, settlement time, broker liquidation terms, and the price that would consume half and all of the planned buffer. Recheck after volatility or contract specifications change.
Common questions
Is there one correct buffer percentage?
No. Contract volatility, concentration, liquidity, broker rules, and the trader's funding horizon change the number.
Does a stop order replace a cash buffer?
No. Gaps and illiquid markets can produce a fill worse than the planned stop.
What should be saved after entry?
Save the requirement, equity, settlement cutoff, stress prices, and the broker's call or liquidation policy.