F&O ban period calculator: check the ratio and official status

This F&O ban period calculator compares entered open interest, or outstanding derivatives exposure, with the entered Market-Wide Position Limit (MWPL). It calculates a manual ratio. Its Status label cannot confirm a stock’s ban status: it does not know whether the stock was already banned and uses a different entry threshold from the official rule. Check the exchange’s dated list. Use futures-equivalent figures, which adjust option positions for their sensitivity to the share price.

What the current ban rule measures

NSE Clearing’s FAQ, updated 14 January 2026, describes FutEq OI: futures-equivalent open interest. This adjusts derivatives positions for delta, their sensitivity to the underlying share. Raw option-contract counts and futures-equivalent exposure are different measures. Use the published combined FutEq quantity with the applicable MWPL, rather than mixing a raw contract count with an exposure limit. The FAQ cites NCL circulars 70085, dated 8 September 2025, and 70555, dated 30 September 2025, for further details.

The FAQ says NCL checks whether end-of-day market-wide FutEq OI exceeds 95% of MWPL, with a resulting ban from the next day. It describes resumption when combined FutEq OI comes down to 80%; the position-limits page explicitly says 80% or below. These sources were checked on 16 October 2026.

A stock that entered ban can therefore remain there after utilisation falls below its entry threshold. Knowing the current ratio without knowing the official status is insufficient. The tool has no field for yesterday’s ban state, so it cannot reproduce that continuation rule.

Where to find the official ban list

NSE publishes a file called Security in Ban Period for the next trade date, F&O segment, on its position-limits page. It also appears under the F&O security-in-ban-period report on NSE's all-reports page. NSE's file documentation names the member-side file fo_secban_DDMMYYYY.csv, where the digits are the date. Check the date inside the file before you rely on it.

Your broker also shows the list. Zerodha, for example, explains the ban in its support pages. Treat a broker screen as a convenience and match it to the exchange file when a trade depends on it.

How the entry and exit levels fit together

The two levels work like a switch with a delay. A stock enters the ban when end-of-day futures-equivalent open interest goes above 95% of the market-wide position limit. It comes out only after the figure falls to 80% or below. Between the two levels, the stock keeps whatever status it had the day before.

The middle row is where most confusion starts. An 88% reading means different things depending on yesterday's status, and this calculator has no field for that.

What changes for your orders during a ban

NSE's position-limits page says that once a security is in the ban period, clients and members should trade only to reduce positions through offsetting trades until normal trading resumes. Your broker may add stricter controls, so read its notice as well.

Margins can also rise. NSE's framework says that when a security in the equity derivatives segment moves into the ban period, the margin rate applicable in the equity segment for that security is increased by 15%, subject to a cap of 100%. Confirm the current rule with your broker, because margin frameworks change.

The form: each input and its actual role

For the ratio, both amounts must refer to the same stock, compatible units and the appropriate reporting date. A per-broker quantity is not the combined market-wide quantity. A share quantity is not a rupee value. Multiplying one by a price while leaving the other as shares makes the division meaningless.

For background on the underlying metric, see open-interest analysis. This calculator does not calculate option deltas, combine a portfolio or aggregate all participants. Those steps must already be reflected in the data you supply.

Worked example: ratio arithmetic, followed by the status check

Use these invented inputs: Current Open Interest 960,000 and MWPL Limit 1,000,000, expressed in compatible futures-equivalent share units. The calculation is 960,000 ÷ 1,000,000 × 100 = 96%. The Oi Percent output shows that ratio, and the tool labels Status as BANNED.

For the official process, an end-of-day ratio above the entry threshold is relevant to the next day’s status. That does not turn an intraday estimate into an exchange declaration. Consult the dated ban file before interpreting the restrictions for a particular session.

Now suppose the same invented stock has exposure of 880,000 with the same limit. Its ratio is 88%. If it was already in ban, that ratio has not reached the resumption level. If it was trading normally before, that same ratio does not establish a new threshold breach. The calculator shows WARNING ZONE for this example, which cannot distinguish those cases.

At an invented exposure of 800,000, utilisation is 80%. That demonstrates the arithmetic at the stated resumption level. The official list and reporting cycle still establish when normal trading resumes. None of these example quantities belong to a real named stock.

What the output cards can establish

Oi Percent is the entered ratio, rounded for display. Status, Action and Risk are preset labels selected from that ratio. They are not exchange instructions, personalised risk assessments or confirmation that an order is permitted.

The tool marks exactly 95% as BANNED, while the official FAQ uses “exceeds 95%”. Near a boundary, rounded percentages can also conceal the underlying value. Use the source quantity and the official status rather than interpreting a rounded card as a regulatory decision.

Read Action and Risk as descriptive labels only. A label such as Trade freely cannot establish trading permission, available margin or whether an existing ban has ended.

Can this calculator tell how long a ban will last?

No dependable duration follows from these inputs. A percentage change assumption does not provide future participant positions, option deltas or the exchange’s subsequent reports. The configured output cards do not provide a verified calendar of ban-entry or exit dates.

There is also an input problem: entering zero or leaving Current Open Interest blank substitutes a positive preset. A zero or blank MWPL also substitutes a preset limit. Do not use the resulting percentage as if it represented zero exposure or a valid missing-data result. The safest interpretation is that the ratio is usable only with checked, positive inputs.

What a stock ban means for an existing position

The restriction concerns the stock’s derivative exposure. It is different from a suspension of its cash-market shares. The cash segment has its own trading and settlement rules. This stock-derivative ban mechanism does not apply to Nifty or Bank Nifty index contracts.

Current monitoring involves a comparison with base futures-equivalent exposure and its direction. The official FAQ treats exposure that does not increase and does not change sign as the relevant non-violation condition. This form has none of your position details, so it cannot assess that condition. Confirm permitted transactions and any stricter platform controls with your broker.

A later-expiry contract still belongs to the same underlying stock. Moving an order to another expiry does not, by itself, prove that it complies. Likewise, calling a trade a hedge does not make this ratio-only calculator capable of checking the combined exposure.

A practical record to keep with the ratio

• Save the official ban list for the intended trade date.
• Keep the combined exposure report and MWPL reference beside the calculation.
• Record whether a value is end-of-day data or a provisional observation.
• Separate the whole market’s utilisation from your own position exposure.
• Keep completed order quantities and prices if you later need to reconcile what changed.

If an order remains pending, market depth concerns available orders; MWPL utilisation concerns a position-limit measure. A ratio below a threshold cannot promise enough liquidity for an exit.

Common mistakes when using the ratio

• Dividing a raw option-contract count by a limit stated in futures-equivalent units.
• Using a single exchange's figure when the rule looks at open interest across exchanges.
• Reading a rounded 95% as proof that the stock is banned or safe.
• Treating the ban list as a forecast. It records a past end-of-day position, not tomorrow's.
• Forgetting that index contracts such as Nifty and Bank Nifty are outside this stock mechanism.

Journal the ban, not just the ratio

A ban shapes what you can do, so it belongs in your trade notes. In OneTradeJournal you log trades by hand, so you can add a line about the stock's status on the day of your trade. Write down the date of the ban file you checked, whether the stock was already banned and what you were allowed to do. If the ban forced you to close a position at a worse price than planned, record it as a cost of the setup. Later you can see how often ban risk affected your trades.

For the basics, see F&O ban list explained. For the wider picture of exposure in a contract, read how to use open interest in trading. Check your lot size in the lot size reference table.

Sources

• NSE Clearing: Futures-equivalent monitoring FAQ (checked 16 October 2026).
• NSE Clearing: Position limits and ban-file link (checked 16 October 2026).
• Zerodha: Stock-derivative ban and index exception (checked 16 October 2026).