Check whether call and put prices are consistent with parity.
Please do not make financial decisions based on these results.
What is the Put-Call Parity Calculator?
Check whether call and put prices are consistent with parity. To use the Put-Call Parity Calculator, enter stock price, strike, years to expiry, risk-free rate, call price, put price; it returns implied put price from call, parity gap, and shows them instantly as you type.
Where the Put-Call Parity Calculator fits
Check whether call and put prices are consistent with parity. The main figure it returns is the Implied put price from call, worked out from the values you enter.
It belongs with the other options & derivatives tools. If you are comparing options or checking a result from another angle, try the Call Option Calculator, Margin Call Calculator or the Black Scholes Calculator.
How to use the Put-Call Parity Calculator
- Fill in the fields. You will need Stock price ($), Strike ($), Years to expiry, Risk-free rate (%), Call price ($), Put price ($). Use real figures from your own records where you can. Fields marked optional can stay at zero.
- Read the result. The highlighted box gives the Implied put price from call, and the cards below show Parity gap. Tables and charts break it down further.
- Test other scenarios. Results update as you type. Change one value at a time to see what drives the answer, and press Reset to go back to the defaults.
Formula and how it works
Example with real numbers
Here is the Put-Call Parity Calculator using the default values shown in the calculator above:
Inputs
| Stock price ($) | 100 |
|---|---|
| Strike ($) | 100 |
| Years to expiry | 1 |
| Risk-free rate (%) | 4 |
| Call price ($) | 9.5 |
| Put price ($) | 5.2 |
Results
| Implied put price from call | $5.58 |
|---|---|
| Parity gap | $0.38 |
With these inputs the calculator returns Implied put price from call: $5.58. Change any value in the calculator to see how the result moves.
What if you change one input?
Sensitivity check: raising Stock price ($) from 100 to 120 (about 20% higher) and leaving everything else as in the example above changes the results like this:
| Result | Example | After the change | Change |
|---|---|---|---|
| Implied put price from call | $5.58 | -$14.42 | -358.5% |
| Parity gap | $0.38 | -$19.62 | -5277.8% |
The input that moves the result most is the one to check twice. Change it in the calculator above to test your own case.
What the results tell you
The results panel of the Put-Call Parity Calculator reports Implied put price from call and parity gap. Compare these figures while changing one input at a time, and use the related calculators below to look at the same situation from another angle.
Method and limits. This calculator applies the formula in the section above to your inputs, in your browser; nothing you enter is stored on our servers. The result is only as accurate as the numbers you enter and the formula shown above. It is for information, not financial, tax or legal advice.
Frequently asked questions
What if parity is violated?
It suggests an arbitrage opportunity, before costs.
Does Black-Scholes work for American options?
It prices European options. American options can be exercised early and may be worth slightly more.
Which option model is used?
The Black-Scholes-Merton model for European options, with an optional dividend yield. American options can be worth more.
Are the results guaranteed?
No. Results depend entirely on the numbers you enter and the formulas shown on this page. Please do not make financial decisions based on them alone; confirm important figures with a licensed professional.
Related options & derivatives calculators
- Call Option Calculator
- Margin Call Calculator
- Black Scholes Calculator
- Option Greeks Calculator
- Options Spread Calculator
- Forward Rate Calculator
- Forward Premium Calculator
- Futures Contracts Calculator
All Options & Derivatives calculators →