How to choose a strike price

Once you decide to trade an option, the next question is which strike. The same view on NIFTY can be expressed with a dozen different strikes, and each gives a very different result. Many beginners choose by price alone, picking the cheapest option they can afford. This guide shows a more careful way: decide what you expect, then pick the strike that pays best if you are right while losing an amount you can accept if you are wrong.

Quick terms: a call is in the money (ITM) when its strike is below the current price, at the money (ATM) when it is at the price, and out of the money (OTM) when it is above. For puts it is the reverse. The ITM, ATM and OTM guide explains these in full.

Start with three questions

1. Which way? Up, down, or no direction (a view on movement only).
2. How far? A target level, for example NIFTY to 25,300.
3. By when? Today, this week, this month. Time decides the expiry and how much decay you face.

Without answers to all three, no strike choice makes sense. A vague "NIFTY should go up" usually leads to buying a cheap OTM call that needs a far bigger move than the trader actually expects.

A worked example: three calls for one view

NIFTY is at 25,000. You expect it to reach about 25,300 by expiry in a week. Three calls (illustrative prices):

Profit or loss per unit at expiry for different NIFTY closes:

The lesson is clear. If your target of 25,300 is hit exactly, the OTM 25,300 call loses everything even though you were right. The ITM and ATM calls both pay. The OTM call only wins big if NIFTY goes well beyond your target. Choosing a strike at your target is one of the most common mistakes buyers make.

Also notice the rupee risk. The ITM call risks ₹300 per unit, the OTM only ₹55. A trader with a fixed budget can buy more OTM lots, but more lots of something that ends at zero is still a total loss. Position size, not strike, should control how much you can lose; see the long call guide.

Delta as a rough probability

An option's delta is also a rough guide to the chance it ends in the money at expiry. A 0.70 delta call is in the money in roughly 70% of outcomes the model considers; a 0.25 delta call in roughly 25%. This is not exact and it is not a forecast, but it is a useful reality check: a cheap OTM option is cheap because the market thinks it will probably expire worthless. The delta guide explains why this approximation works.

Use the expected move to see what is priced in

The at-the-money straddle tells you how far the market expects NIFTY to move by expiry. Here is that range, worked out live:

Compare your target with the edges of the range. If your target is inside it, the options market already expects a move that large, and OTM calls at your target are unlikely to pay well; ITM or ATM strikes fit better. If your target is well outside it, you are betting on a bigger move than the market prices, which is where OTM options can pay many times over, if you are right.

Use open interest to see where others are positioned

Strikes with very large open interest often act as levels traders watch. Large call open interest above the price is often read as resistance and large put open interest below as support. Here are NIFTY's open interest levels:

Look for the strikes with the tallest call and put bars. A target beyond a large call wall may be harder to reach; option sellers often place short strikes just beyond these walls. These are tendencies, not rules, and the levels can shift during the day; see support and resistance from open interest.

Choosing strikes as a seller

Sellers think the other way round. They want strikes that are unlikely to be reached, while still collecting enough premium to be worth the risk.

• Closer strikes (ATM, high delta) collect more premium but are tested more often and need more active management.
• Further strikes (low delta, outside the expected move) are tested less often but pay little, and one large move can wipe out many small gains.
• Many sellers pick strikes by delta, for example selling 0.15 to 0.30 delta options, or by placing them at or outside the expected move. Always define the maximum loss, for example by buying further options to form a spread.

Example: with NIFTY at 25,000 and an expected move of about 300 points, a seller might sell the 25,350 call and the 24,650 put, just outside the range, and buy the 25,550 call and 24,450 put as protection. The credit is smaller than selling closer strikes, but the price has to travel further before the trade is in trouble, and the bought options cap the worst case.

Other practical checks

• Liquidity. Prefer strikes with tight bid-ask spreads and solid open interest. A theoretically perfect strike is useless if you cannot exit at a fair price; see the bid-ask spread guide.
• Time to expiry. With little time left, OTM options decay fast and need the move immediately. With more time, the gap between strikes matters less.
• Implied volatility. When IV is high, all options are expensive; buyers may prefer ITM options (less time value) or spreads, and sellers get more premium for the same distance.
• Events. Before results or policy days, premiums are inflated and drop after the event.

Puts follow the same logic in the other direction. With NIFTY at 25,000 and a view that it falls to 24,700, an ITM 25,200 put needs a smaller fall to pay, while a 24,700 put at the target would expire worthless if the target is hit exactly. Write down your target and timeframe, list three strikes, and work out each one's result at the target before choosing.

The strategy builder lets you compare strikes side by side and see the payoff at different prices before you decide.

Common mistakes

• Choosing by price alone. The cheapest option is cheap because it probably expires worthless.
• Setting the strike at the target. If the target is hit exactly, that option is worth nothing.
• Ignoring time. A right view that takes too long still loses on an OTM option.
• Buying more lots of a cheaper strike to "make it count". It raises the total amount at risk.