About OpCalc

What is OpCalc?

OpCalc is a free options profit calculator that models the theoretical profit and loss of any options strategy before you place a trade. Enter a ticker, select a strategy, pick a strike and expiration, and see the estimated P/L at every stock price — from today through expiration.

The tool supports single-leg positions (buying or selling calls and puts), two-leg spreads (bull call spreads, bear put spreads), and custom multi-leg strategies with up to 8 legs (iron condors, straddles, butterflies, and more).

How it works

OpCalc calculates option prices using the Black-Scholes model, the industry-standard formula for theoretical option pricing. For each stock price on the chart, the tool computes the value of every leg in your position at multiple dates between now and expiration, then sums them to produce your net P/L.

The tool also calculates the net Greeks (delta, gamma, theta, vega) for your entire position and estimates the probability of profit at expiration based on the implied volatility of the options you've selected.

Limitations

The Black-Scholes model assumes lognormal stock price distribution, constant volatility, no dividends, and European-style exercise. In reality, volatility changes constantly, stocks pay dividends, and American-style options can be exercised early. These factors cause actual P/L to differ from modeled P/L.

Probability of profit values shown in the calculator are risk-neutral probabilities — the values derived from current option prices — not real-world physical probabilities. The actual probability of a position being profitable in real markets may differ.

The synthetic options chain uses an asymmetric volatility skew based on a constant base IV. Real market IV varies by underlying, time, and event proximity. Chain prices are educational approximations, not live market quotes, and do not represent executable prices.

The calculator uses the mid price (average of bid and ask) as its reference premium. In practice, you'll fill closer to the ask when buying and closer to the bid when selling. On illiquid options, this difference can be significant. Bid/ask spreads shown are estimated at 2.5% — real spreads range from a fraction of a percent on liquid ETF options to over 30% on illiquid weeklies.

The risk-free rate used in pricing is held constant at 4.5%. The model does not account for early assignment risk on American-style options, dividend ex-dates, or stochastic volatility.

Stock quote data is provided by Finnhub and may be delayed by approximately 15 minutes. Delayed data is not suitable for active trading decisions.

Terms of service

By accessing or using OpCalc, you agree to the following terms. If you do not agree, do not use this site.

OpCalc is intended for users aged 18 and older. By using this site you represent that you are of legal age to trade options in your jurisdiction.

You may use OpCalc for personal, non-commercial purposes. You may not reproduce, redistribute, or scrape content or data from OpCalc without written permission.

OpCalc reserves the right to modify, suspend, or discontinue any part of the site at any time without notice. We reserve the right to update these terms at any time. Continued use of the site after changes constitutes acceptance of the updated terms.

These terms are governed by the laws of the United States. Any disputes arising from use of this site shall be resolved in the applicable courts of the United States.

Terms of use and disclaimer

OpCalc provides theoretical estimates for educational and informational purposes only. Nothing on this site constitutes financial advice, investment advice, trading advice, or a recommendation to buy or sell any security. The content on this site should not be treated as such.

OpCalc is not a registered investment adviser, broker-dealer, or financial planner under any applicable law. It does not provide personalized investment advice and does not take into account any individual's financial situation, objectives, or risk tolerance.

Probability of profit estimates are generated by mathematical models using implied volatility and Black-Scholes pricing. They are not predictions of actual outcomes. Implied volatility changes constantly and model-based probabilities have no guaranteed relationship to real-world results.

All P/L calculations are theoretical estimates. Actual results will differ materially due to market conditions, liquidity, transaction costs, commissions, bid-ask spreads, dividend effects, early assignment risk, and other factors not captured by the model.

Options trading involves substantial risk of loss and is not appropriate for all investors. You can lose the entire amount invested in an options position. Before trading options, carefully consider your experience, financial objectives, and risk tolerance.

Users are solely responsible for all trading and investment decisions. OpCalc and its operators expressly disclaim any liability for losses, damages, or costs of any kind arising from the use of or reliance on any information, estimates, or calculations provided by this tool. By using this site, you agree to these terms.

Contact

General inquiries: hello@opcalc.app

Privacy and data requests: privacy@opcalc.app

Bug reports: bugs@opcalc.app