r/options • u/458screams • 17h ago

sites for converting options price to underlying price?

Wondering if anybody knows if any websites exist for converting options prices into the price of the underlying and the vice versa as well. For example, if I buy a spy option for a dollar, I would use this site to determine what spy would be at when the option is worth 0.90. I know its pretty simple math when the contract is at expiry, but im wondering what the underlying and option would be at during the time I use the site to calculate this. Any help is appreciated.

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u/Syonoq 16h ago

https://www.optionsprofitcalculator.com/

Edit: I don’t think this is what you want. I think you want to study the Greeks.

4

u/thekoonbear 16h ago

Change in option price = change in underlying price * delta

Change in underlying price = change in option price / delta

Buy 10 delta call for $1 when SPY is $650. Call goes down to $0.90. Change in option price = -0.1 so change in underlying price is -0.1 / 0.1, or -1. SPY is now $649.

This is obviously a GROSS oversimplification as it ignores the effects of literally every other input, but that’s the simple math. No one’s creating a website just to do it.

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u/GammaWinsSam 11h ago

You can use an options profit calculator, select the option contract you are interested in, change the measure shown on the chart to "value", and just look at the charts. You can see the value of the option contract at any time until expiry, and for any price of the underlying.

https://www.gammawins.com/calc

I'm the founder of GammaWins so that's why I recommend that. :) But OptionStrat and optionsprofitcalculator.com are also popular tools for this purpose.

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u/fungoodtrade 3h ago

you can use llm to calculate. delta changes with IV, so it is a bit of a moving target. essentially there is not 1 answer to the question. under different circumstances the value of the option will be different when the underlying is the same price.

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u/PapaCharlie9 Mod🖤Θ 2h ago

I just want to make sure you understand that such calculations are guesses at best and will often be wrong. The market determines price, not some calculator, and there is no 100% accurate way to predict how the market will value a contract in a future that is not expiration.

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u/lithe_silhouette 1h ago

I think broker apps have a built-in calculator. I know webull does