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Your stop-loss shouldn't change because the position is "index options" instead of "equity." What changes is how you convert the price move into rupees โ and that's exactly what most traders skip.
Your stop-loss in rupees is: (Entry Price โ Stop-Loss Price) ร Quantity. The formula stays the same across stocks, index options, and commodities โ what changes is the quantity. For stocks, quantity is the number of shares. For index options, it's lot size ร number of lots (currently 65 for a NIFTY lot, 30 for a Bank Nifty lot, and 20 for a Sensex lot). For commodities, it's lot size ร number of lots as defined by the exchange for that contract. Calculate this number before entry, not after the trade is already open.
A stop-loss calculator converts a price-based stop-loss into a rupee amount by multiplying the per-unit risk by your quantity โ so you know exactly what a trade costs you if it fails, before you take it.
A trader tells you their stop-loss is "โน10 below entry" and it sounds precise. But โน10 on a stock held as 50 shares is a very different number than โน10 on a NIFTY option held as 65 quantity per lot, multiplied across three lots. The price distance is the same. The rupee risk is not. This is where a lot of position sizing quietly goes wrong โ not in the chart reading, but in the arithmetic that connects a price level to an actual account impact.
A price-based stop-loss tells you where the setup is invalidated. A rupee-based stop-loss tells you what that invalidation costs. Both numbers matter, and they're connected by one calculation traders tend to skip: multiplying the price risk by the actual quantity they're trading.
Here's where it gets interesting: two traders can place what looks like an identical stop-loss โ same distance in points โ and end up with completely different rupee exposure, purely because one is trading equity in single shares and the other is trading index options in lots. The setup doesn't know the difference. Your account does.
The core formula doesn't change. What changes is how quantity is defined for each instrument.
Rupee Risk = (Entry Price โ Stop-Loss Price) ร Quantity
For a short position, reverse the direction: Rupee Risk = (Stop-Loss Price โ Entry Price) ร Quantity.
Stock and equity trading: quantity is simply the number of shares you hold. There's no lot multiplier โ the price move and the share count are all you need.
Index options (NIFTY, Bank Nifty, Sensex): quantity is lot size ร number of lots. Lot sizes are fixed by the exchange and revised periodically, so always confirm the current figure before trading. As of the exchange's current specification: a NIFTY lot is 65 quantity, a Bank Nifty lot is 30 quantity, and a Sensex lot is 20 quantity.
Commodity trading (MCX): quantity is also lot size ร number of lots, but lot sizes vary significantly by commodity โ gold, silver, crude oil, and natural gas all carry different contract specifications. Check the specific contract's lot size on the exchange before calculating.
Yahan problem calculation ki nahi, quantity define karne ki hai โ the math itself is simple; where traders slip is in getting the quantity for their specific instrument wrong.
Select your instrument type, enter your entry and stop-loss prices, and the calculator handles the quantity math for you.
Say you're buying NIFTY call options at a premium of โน220, with a stop-loss at โน200 based on where the setup would be invalidated. You take 2 lots. At the current NIFTY lot size of 65, that's a total quantity of 130.
Rupee risk = (โน220 โ โน200) ร 130 = โน2,600. That's the number that should be checked against your per-trade risk limit before the order goes in โ not the โน20 point difference alone, which on its own tells you very little about what the trade actually costs.
| Instrument | Quantity Unit | What Determines Rupee Risk |
|---|---|---|
| Stock / Equity | Number of shares | Price move ร exact share count you hold. |
| NIFTY Options | Lots (65 qty per lot) | Premium move ร 65 ร number of lots. |
| Bank Nifty Options | Lots (30 qty per lot) | Premium move ร 30 ร number of lots. |
| Sensex Options | Lots (20 qty per lot) | Premium move ร 20 ร number of lots. |
| Commodity (MCX) | Lots (varies by contract) | Price move ร contract-specific lot size ร number of lots. |
Lot sizes shown are current at the time of writing and are set by the exchange, which revises them periodically based on contract value. Always verify the live lot size on the NSE, BSE, or MCX circular before placing a trade.
A โน15 stop-loss sounds small regardless of instrument. It isn't. The same point distance produces very different account impact depending on whether you're holding 50 shares or 3 lots of options.
Exchange lot sizes get revised from time to time. A trader calculating position size off a lot size that changed months ago ends up with a rupee risk figure that's simply wrong, even though the formula itself was applied correctly.
Calculating the rupee risk for one lot and then trading three lots without re-multiplying is one of the more common arithmetic slips โ the risk triples, but the number in the trader's head doesn't.
Gold, silver, crude oil, and natural gas all carry different lot sizes and contract values on MCX. A stop-loss rule built around one commodity's lot size doesn't transfer cleanly to another without recalculating.
At the time of writing, a NIFTY lot is 65 quantity, a Bank Nifty lot is 30 quantity, and a Sensex lot is 20 quantity. These are set by the exchange and revised periodically, so confirm the live figure on the NSE or BSE website before trading.
Multiply the difference between your entry premium and stop-loss premium by your total quantity, where total quantity is the lot size multiplied by the number of lots you're trading. This gives you the rupee amount at risk if the stop-loss is hit.
The formula is the same โ price risk multiplied by quantity โ but the lot size itself varies by commodity and contract, so it needs to be checked separately for gold, silver, crude oil, or any other MCX instrument rather than assumed.
Because the two indices have different lot sizes. A 20-point stop-loss multiplied by a 65 quantity NIFTY lot produces a different rupee figure than the same 20 points multiplied by a 30 quantity Bank Nifty lot.
Before. Calculating it after the trade is open tends to produce a rupee figure that gets rationalized to fit the position already taken, rather than a genuine risk limit that was decided in advance.
Yes. Stop-loss placement tells you where the setup fails. Position sizing, driven by quantity and lot size, tells you how much that failure costs. Both decisions are needed together โ a well-placed stop-loss with an oversized position can still produce a damaging loss.
Before you think about the target, know exactly how much you are willing to lose if the setup fails โ in rupees, converted through your actual quantity, not just in points on a chart. Run every trade through the calculator above before the order goes in, whether it's a stock position, an index options lot, or a commodity contract, and confirm your lot size against the exchange rather than memory.
If you want a structured, chart-based framework for setting entries, confirmation, and stop-loss levels across NIFTY and Bank Nifty options specifically, the CPR Brahmastra webinar walks through the rules step by step.
Explore the CPR Brahmastra WebinarThis article is for educational purposes only and does not constitute investment advice. Lot sizes for index options and commodities are set by the exchange and revised periodically โ confirm current figures on the NSE, BSE, or MCX website before trading. Trading in the securities and commodities market involves risk of loss. Past performance and hypothetical examples are not indicative of future results. Please consult your financial advisor before investing.
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