Put-call parity check calculator
The model-free relationship, tested.
Interactive: put-call parity checkMedium
The one relationship in options that holds without any model: a call minus a put must equal the stock minus the discounted strike. When it doesn't, someone is about to be arbitraged.
- Theory: S − K·e^(−rT)
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- Actual: C − P
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- Mispricing
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- Reading
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European options, no dividends. Real gaps are usually dividends, borrow costs or early-exercise value rather than free money — but the check is how you find out which.
The idea behind it
This calculator belongs to Equity Derivatives, where the mechanism it computes is explained step by step, with the formula, what each input means and where the simple model stops being right. Everything is computed in your browser; nothing you type is sent anywhere.
Instruments it applies to
- Equity Option — The right — not the obligation — to buy or sell a stock at a fixed price. The atom of derivatives.
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