How much does theta decay cost me per day on my options position?
Enter Your Position
Your Result
Fill in the fields on the left and click Calculate to see the estimated dollar cost of time decay on this position.
How this is calculated
Daily theta cost equals the absolute value of theta per share, multiplied by 100 shares per contract, multiplied by the number of contracts.
Weekly theta cost multiplies the daily estimate by 5 trading days. It is not a separate measurement, just the daily number scaled up.
Theta is a snapshot from the option pricing model at the moment you pulled it, not a fixed daily bill. It changes as the stock price moves, as implied volatility changes, and as expiration gets closer. Theta decay typically accelerates in the final weeks before expiration.
This assumes one standard equity option contract represents 100 shares.
This does not account for changes in the underlying stock price, dividends, interest rates, or shifts in implied volatility, all of which can offset or add to the effect of time decay on the option's actual price.
Risk & liability disclaimer: This calculator produces a mathematical estimate based on the theta value and inputs you enter at a single point in time. It is not financial advice and does not guarantee any trading outcome. Actual time decay can differ from this estimate as market conditions change, and options trading involves risk of loss, including the loss of the entire premium paid. Trading Habits is not a broker-dealer, registered investment adviser, or tax professional, and is not affiliated with any broker, exchange, or data provider. We do not guarantee this tool is error-free or suitable for your situation. Always verify results independently and consult a licensed professional before making any trading or financial decision. You could lose some or all of the capital you trade with.
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