Frequently asked questions

Yes. Every strategy, every feature and every page is free to use, with no account required and no usage limits. Nothing is held back behind a subscription.

No. There is no sign-up, no login and no account. Calculations you save are stored in your own browser rather than on a server, and shared links carry the position inside the URL itself.

By default, no. The calculator runs on prices you enter, or on theoretical prices generated by a pricing model and clearly badged as such. Live market data is built but currently switched off pending options data licensing, and when it is on, every figure carries a timestamp and a feed label.

The market data disclosure explains exactly what each mode means.

Almost always because of a different input rather than a different formula. The most common causes are a different implied volatility, a mid price versus a price you can actually be filled at, a different probability model, and theta quoted per trading day instead of per calendar day. Profit at expiration is arithmetic and should match exactly if the inputs match; anything before expiration is a model estimate and will differ.

There is a full list of the reasons, in order of how often each one is the culprit, on the accuracy page.

It is the price the underlying has to reach at expiration for the position to be worth exactly what you paid for it, including commissions and fees. It is not the strike price. For a long call it is the strike plus the premium, which is why buying a call that is already in the money still needs the stock to move before you make anything.

Because it is unlimited, and showing a large finite number in its place would be misleading. A naked short call loses more as the stock rises, with no ceiling. The calculator works out whether the payoff flattens or keeps going by examining its slope beyond the outermost strike, and reports Unlimited as a distinct answer rather than a very large figure.

They are rough. They assume prices follow a lognormal distribution, which understates how often large moves happen in real markets, so any probability of an extreme outcome is too comforting. Every probability on the site is displayed with the distribution, volatility and drift assumption that produced it, so you can see why another platform shows a different number from the same data.

Black-Scholes-Merton with a continuous dividend yield for European-style pricing, and a Cox-Ross-Rubinstein binomial tree for American-style options where early exercise matters. Greeks are computed analytically rather than by numerical differencing, and implied volatility is solved by Newton-Raphson with a bisection fallback when vega is too small for it to be stable.

The formulas, the units and the reference values they are tested against are all set out on the methodology page.

Yes. The custom builders take two to eight legs in any combination of calls, puts, strikes and expirations, plus a stock position. Every strategy on the site, named or custom, runs through the same calculation engine, so a custom position gets the same exact breakevens and the same unlimited-risk detection as a textbook one.

Start from the custom strategy builder.

Yes. Each leg carries its own expiration, which is what calendar and diagonal spreads require. The expiration payoff is computed at the nearest expiration with the remaining legs valued by the model at that date, and the date slider lets you step through the period in between.

Nothing that identifies you. There is no account, and calculations you save stay in your own browser rather than being uploaded. Shared links contain the position itself, so nothing about them needs storing on a server either.

The privacy policy states this in full.

No. It is an educational calculator. It tells you what a position pays under stated assumptions, and it cannot tell you whether those assumptions will hold or whether the trade is a good idea. Verify every price with your broker before trading.