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REDDIT

Can someone provide a shortcut to approximate IV if all of the other numbers are known?

T
Apr 18, 2026 · 18:04

For example, with 30 DTE, the ATM (711) SPY put option is around $12. I can see on Robinhood that the IV is 14.5%. If I didn’t have a platform to tell me what the IV is, is there a quick way I could calculate it using some type of back of the envelope math?