Theta Decay Calculator
Model how much premium may decay as expiration approaches if price and volatility stay constant.
Ready.
Time decay in practice
Theta decay is not linear. It usually accelerates as expiration gets closer, especially for at-the-money options. This tool compares current theoretical value against a future date with fewer days remaining, assuming the stock price and IV do not change.
That assumption will rarely hold in real markets, but it isolates time as a risk factor. It is useful when deciding whether to buy premium, sell premium, or roll a position.
Educational only. Real theta behavior changes with IV, skew, dividends, and movement in the underlying.