See exactly how option premium erodes day by day as expiry approaches. The silent killer of option buyers — visualize theta decay before you hold overnight.
See exactly how option premium erodes day by day as expiry approaches. The silent killer of option buyers — visualize theta decay before you hold overnight.
Current Premium
₹477.72
Value at Expiry
₹0.00
Total Decay (pts)
₹477.72
Total Decay (₹)
₹35,829
per lot (75 shares)
Premium Decay Over Time
Day-wise Decay Snapshot
| Day | DTE | Premium | Theta/day | Decay (₹) |
|---|---|---|---|---|
| 0 | 30 | ₹477.72 | ₹9.09 | ₹682 |
| 7 | 23 | ₹410.94 | ₹10.05 | ₹754 |
| 15 | 15 | ₹323.88 | ₹11.91 | ₹893 |
| 22 | 8 | ₹229.99 | ₹15.48 | ₹1161 |
| 23 | 7 | ₹214.07 | ₹16.39 | ₹1229 |
| 27 | 3 | ₹136.68 | ₹23.87 | ₹1790 |
| 29 | 1 | ₹77.32 | ₹39.74 | ₹2981 |
| 30 | 0 | ₹0.00 | ₹0.00 | ₹0 |
DETAILS
This section explains what the calculator does, what goes into the result, and how to interpret the output so you can apply it confidently.
This calculator turns a few key inputs into a clear output you can act on — a number that traders and investors commonly use for planning and decision-making.
Use it to compare scenarios quickly and to understand the trade-offs behind the final result.
Treat the output as a planning number. Small changes in inputs (time, rate, price, quantity, risk, or cashflows) can change the outcome meaningfully — so keep assumptions realistic.
If the tool returns multiple outputs, focus on the ones that drive decisions (e.g., net result, breakeven, or risk-adjusted value), not just the biggest number.
CE: Spot ₹24,000, Strike ₹24,000, DTE 30, IV 15%, Rate 6.5%, Lot size 75
Graphical view
PE: Spot ₹24,000, Strike ₹24,500, DTE 15, IV 25%, Rate 6.5%, Lot size 75
Graphical view
Even with intrinsic value at expiry, option premium can still decay significantly as time value collapses into intrinsic.
HOW IT WORKS
Input spot, strike, DTE, implied volatility, and risk-free rate.
Select call or put option type.
View a premium decay chart and table showing how much value evaporates each day.
FAQ
Time value decays non-linearly — it decays slowly when there is lots of time, and then rapidly in the final 7-10 days. This is because uncertainty (hence premium) collapses as expiry nears.
Buying options in the last week is very risky due to rapid theta decay. Unless you are expecting an immediate move, the odds strongly favour sellers in the final days.
Yes — options premium typically accounts for weekend decay, meaning Monday open often shows 3 days of theta already priced in (Friday's theta × 3).
Use the current implied volatility from NSE's option chain for the specific strike. For Nifty ATM options, IV typically ranges between 10% and 25%.
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