On Wednesday 10 Jun 2026 Nifty closed at 23,214.95. Two calls expiring the next Tuesday sat on the board: the 23,250 strike at Rs 163.60 a unit and the 24,000 strike at Rs 9.55. If Nifty added 100 points, the first would gain about Rs 48.4 and the second about Rs 5.0. Same index, same move, almost ten times apart. That ratio is delta, and I look at it before I look at the price. By Tuesday 16 Jun Nifty had added 774.2 points. The first call settled at Rs 739.15. The second expired worthless, with the index 10.85 points short of its strike. This lesson explains both outcomes.
3By the end you can
- Read delta as rupees of premium per index point, and turn it into rupees per lot.
- Count how many units of the future an option position behaves like.
- Say when delta works as a rough chance of finishing in the money, and why it is not a chance of profit.
The idea, plainly
Delta is a speedometer. It reads how many rupees an option's price moves for each point the index moves, at this moment. A delta of 0.484 means the option gains about 0.484 rupees for each point the index gains. A call's delta runs from near zero far out of the money to near one deep in the money. A put's runs from near zero to near minus one, because a put gains when the index falls. At the money, the strike nearest the forward, a call sits near one half and a put near minus one half.
Delta runs from 0 to 1 along an S, and the S steepens as expiry nears
Delta is the first of five Greeks. Each is the slope of the option's price against one input, with the others held still.
| Greek | The question it answers | Module |
|---|---|---|
| Delta | How much does the price move for one point of the index? | This one |
| Gamma | How fast does delta itself change? | I09 |
| Theta | How much does one day passing take away? | F22 |
| Vega | How much does one point of volatility add? | I10 |
| Rho | How much does one point of interest rate add? | I11 |
Delta does three jobs. I treat them as three readings of one number.
Speed: rupees per point
Prices are rupees per unit and a lot is 65 units. So one lot of the 23,250 call moves 0.484 x 65, which is Rs 31.5 for every index point. A put works the same way with the sign flipped. The calculation behind it is the one formula on this page.
d1 = [ln(F/K) + s*s*T/2]
/ (s * sqrt(T))
Call delta = N(d1)
Put delta = N(d1) − 1
Read one more paragraph, 41 words
F is the future, K the strike, s the implied volatility and T the years to expiry. N turns d1 into a number between 0 and 1. Black 76 adds a small discount factor for interest, which the Greeks calculator includes.
Hedge ratio: how much of a future the option behaves like
Rupees per point for one lot is also the number of units of the Nifty future that earn the same rupees per point. The 23,250 call lot behaves like 31.5 units of the future, about 48% of a 65 unit lot. That is the hedge ratio, and it is arithmetic. It also drifts as the index moves, which is why holding a hedge is a job. For several legs, add the lot deltas with their signs. One lot bought of the 23,250 call and one lot sold of the 23,500 call give a position delta of (0.484 less 0.268) x 65, which is 14.1 units of the future. That is well under one leg alone, because the sold call gives some back. Module I12 does this for whole strategies.
2 terms this section turns on
Probability shortcut: odds of finishing in the money
A call finishes in the money if the index ends above the strike, so delta works as a rough chance of that. The chain itself shows why, and module F17 explains each of its columns. The call price falls as the strike rises, and the fall per point of strike is the market's own chance of finishing above it, apart from a small interest factor.
Each 100 points on the strike takes about Rs 48 off a call near the money
| Calls | Strike | Puts |
|---|---|---|
| Settle | Settle | |
| 246.10 | 23,100 | 116.95 |
| 215.75 | 23,150 | 136.70 |
| 188.00 | 23,200 | 158.80 |
| Spot 23,214.95 | ||
| 163.60 | 23,250ATM | 182.45 |
| 139.75 | 23,300 | 209.15 |
| 118.95 | 23,350 | 238.35 |
| 100.20 | 23,400 | 269.15 |
Shaded cells are in the money. Prices are settlement prices in rupees per unit.
Read one more paragraph, 58 words
The fall between the 23,200 and 23,300 strikes is Rs 48.25 over 100 points, which is 0.482 a point. The Black 76 delta of the 23,250 call in between is 0.484. Two routes, nearly the same answer. These are odds implied by prices. They are not a forecast, and they are not a count of past outcomes.
Worked example: two calls, one week, 10 to 16 Jun 2026
Take the weekly chain of 10 Jun 2026. The forward was 23,229.26, read off a call and a put at one strike because a weekly has no future, with 6 days to the Tuesday 16 Jun expiry, which settled at the index close of 23,989.15. We read delta off each call's own implied volatility.
| Step | What we read | 23,250 call | 24,000 call |
|---|---|---|---|
| 1 | Premium on 10 Jun, rupees per unit | 163.60 | 9.55 |
| 2 | Implied volatility of the strike | 14.6% | 15.4% |
| 3 | Delta | 0.484 | 0.050 |
| 4 | Rupees per index point, one lot of 65 | 31.5 | 3.3 |
| 5 | Delta times the 774.2 point rise | 375.0 | 38.8 |
| 6 | Settlement on 16 Jun, per unit | 739.15 | 0.00 |
| 7 | Actual change in value, per unit | 575.55 | −9.55 |
On the same day the index move does most of the work, and volatility moves the rest
| Index move | Same day, rupees per lot | ||
|---|---|---|---|
| IV −2 | IV same | IV +2 | |
| −2% | −9,539 | −8,803 | −7,926 |
| −1% | −7,015 | −5,753 | −4,431 |
| 0% | −1,543 | −1 | +1,542 |
| +1% | +7,529 | +8,884 | +10,285 |
| +2% | +19,670 | +20,537 | +21,534 |
Green is profit and red is loss; deeper colour means a larger amount. The outlined cell is the starting point.
Read 3 more paragraphs, 193 words
Row 5 undershoots row 7 for the first call. Delta is a speed at one moment, and as the call moved toward the money its delta climbed toward one. The bend is gamma. For the second call row 5 overshoots badly. It needed the index above 24,000 at the close and the index never got there. Six days of time ran out first. Delta is one force of five.
Time is the next one. The first call lost about Rs 14.44 a unit to a single day of decay. So on that day the index had to climb about 30 points just to leave the premium where it was. That is theta divided by delta, and it is why a rising index does not always lift a premium.
That is why the first thing to look at in a call that is not rising is its delta. A far strike with a delta of 0.050 needs 20 points of index for each rupee it gains. This is one of three reasons a premium fails to follow the index. The other two are time, in module F22, and volatility, in module I10.
The common mistake
The claim: A call with a delta of 0.30 has a 30% chance of making money.
Delta is closer to the chance of finishing in the money, and an option in the money can still lose. The 23,250 call cost Rs 163.60, so it needs the index above 23,413.60 at expiry to make a rupee. The nearest strike below that, 23,400, has a delta of 0.35, against 0.484 for the strike itself. The chance of profit is the smaller number. Delta is also not fixed: it moves with the index, with time and with volatility, so it describes the prices of one day, not the week that follows.
Key takeaways
- Delta is the rupees an option gains for each one point rise in the index.
- A call's delta runs from 0 to 1, a put's from 0 to minus 1.
- Multiply delta by the lot size of 65 to get rupees per point.
- Delta is a speed at one moment, so big moves bend away from it.
- Delta roughly gives the chance of finishing in the money, not of making a profit.
- Delta times units shows how much of the future an option position mimics.
Two terms to hold on to from 14.7
Before you trade. Derivatives trading carries a high risk of loss. SEBI's study "Profitability of Individual Traders in the Equity Derivatives Segment (FY25 to FY26)" (August 2026) found that 87.7% of individual traders in equity F&O made net losses in FY26, with aggregate net losses of Rs 91,685 crore. Read the SEBI study