Theta Decay Calculator.
See Exactly What Time Costs You Daily.
Calculate the precise daily dollar loss from theta decay on any options position. Understand the theta cliff, weekend decay, and how IV affects your time decay.
Theta works against option buyers every single day
Even if the stock doesn't move, you lose money. ATM options can lose 30-50% of their value in the last 30 days. Use the calculator to see your exact daily cost.
Options Greeks Calculator — Focus on Theta
Enter your option details below. Look at the Theta output — it shows daily dollar decay per contract (100 shares).
Options Parameters
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Greeks Analysis
Option sensitivity metrics
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The Theta Cliff: Why Decay Accelerates
Theta decay is not linear. It follows the square root of time — meaning an option loses value much faster in its final weeks than its early life. This is called the "theta cliff."
| Days to Expiry (DTE) | Time Value Remaining | Daily Decay Rate |
|---|---|---|
| 90 DTE | ~100% | Slowest — low urgency |
| 60 DTE | ~82% | Gradual |
| 45 DTE | ~71% | Moderate — good selling zone |
| 30 DTE | ~58% | Noticeable acceleration |
| 14 DTE | ~39% | Rapid decay begins |
| 7 DTE | ~28% | Very fast — dangerous for buyers |
| 2 DTE (0DTE zone) | ~15% | Extreme decay — theta gang heaven |
Key Formula
Time Value Remaining ≈ √(DTE ÷ Original DTE) × Original Time ValueThis is why selling at 45 DTE (not 90 DTE) is the sweet spot — you capture most of the theta without waiting too long.
Theta: Buyers vs Sellers
Option Buyers (Negative Theta)
- Lose money daily from theta
- Need the stock to move fast
- Every day that passes hurts you
- Weekend = 3 days of free decay for sellers
- Worst position: long ATM options near expiry
Option Sellers (Positive Theta)
- Collect theta every day
- Profit when stock stays flat
- Time is on your side
- Weekend = free premium collected
- Best position: short ATM options, 30-45 DTE
The trade-off: Option sellers profit from theta but face unlimited risk (naked) or large potential losses (spreads) if the stock moves sharply. High theta income = high gamma risk. Always define your max loss.
Strategies to Manage Theta
Buy options ≥45 DTE
Gives you time for the trade to work. Theta is lower in percentage terms. Avoid buying options with less than 21 DTE.
Sell options at 30-45 DTE
The sweet spot for theta selling — rapid decay without the extreme gamma risk of 0-7 DTE options.
Use spreads, not naked options
Defined-risk spreads let you sell theta while capping max loss. Iron condors and credit spreads are popular theta strategies.
Close winners at 50%
When a short option loses 50% of its value, close it. You've captured most of the theta with less time left — and less risk of a sudden reversal.
Avoid buying before earnings
Implied volatility (and thus option premium) spikes before earnings. After earnings, IV crashes — destroying value even if you were right on direction.
Target high IV for selling
Sell options when IV rank is above 50%. High IV means you're collecting inflated premiums that are more likely to decay toward fair value.
Frequently Asked Questions
What is theta decay in options?▾
Theta is the daily dollar amount an option loses due to the passage of time, all else being equal. An option with Theta = -$5 loses $5 in value every day, even if the stock price doesn't move. Theta measures the erosion of extrinsic (time) value as expiration approaches. Option buyers are hurt by theta; sellers benefit from it.
How do I calculate theta decay on my options position?▾
Use the calculator above: enter the underlying price, strike price, time to expiration, implied volatility, and interest rate. The calculator uses the Black-Scholes model to compute Theta — the exact daily dollar decay. Multiply Theta by days held to estimate total time decay impact.
Does theta decay accelerate near expiration?▾
Yes — this is the 'theta cliff.' Time decay is roughly proportional to the square root of time remaining. An option with 30 DTE loses value much faster than one with 90 DTE. In the final 7-14 days, theta decay accelerates dramatically. ATM options lose the most time value in absolute terms as expiration approaches.
Do options lose value on weekends?▾
Yes. Options prices embed 3 days of theta over the weekend (Friday to Monday). When markets open on Monday, the option has already 'decayed' through Saturday and Sunday. Theta sellers often sell on Thursday/Friday to capture weekend decay. The actual calculation in Black-Scholes uses calendar days, not trading days.
What is a Theta Gang strategy?▾
Theta Gang refers to traders who systematically sell options to collect time premium. They profit from theta decay: selling covered calls, cash-secured puts, credit spreads, and iron condors. The strategy works best in sideways-to-slightly-directional markets with elevated implied volatility. The risk is sharp moves that overwhelm the collected premium.
How does implied volatility affect theta?▾
Higher implied volatility means higher option premiums, which also means higher absolute theta (more dollar decay per day). A $5 ATM option will decay faster than a $2 ATM option. When IV drops (like after earnings), option values fall sharply — this is IV crush working alongside normal theta decay.
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Disclaimer: Options trading involves significant risk of loss. Theta calculations use the Black-Scholes model which assumes constant volatility — actual decay may differ. This calculator is for educational purposes only. Consult a licensed financial advisor before trading options.