August 30, 2026
It isn't a forecast, and it doesn't know direction. It's a number worked backwards out of a price, which is why a high one is a warning rather than an opportunity.
An option pricing model takes a handful of inputs — the stock price, the strike, the time remaining, interest rates, and a volatility figure — and produces a price. All of those inputs are observable except volatility, because future volatility hasn't happened yet.
So the market runs the model backwards. Take the price the option is actually trading at, hold the other inputs fixed, and ask what volatility number would have to be true for the model to produce that price. That number is the implied volatility. It's implied by the price rather than used to set it.
Which means IV is not a prediction anyone made. It's a summary of what buyers and sellers are collectively willing to pay, translated into units of volatility so it can be compared across strikes, dates, and stocks.
IV is quoted as an annualized standard deviation of returns. An IV of 30% means the market is pricing a range of roughly plus or minus 30% over one year, at one standard deviation — which for a normal distribution covers about 68% of outcomes.
Nobody trades one-year options, so the useful move is converting it to the period in front of you:
price × IV × √(days ÷ 365)
A $50 stock with 30% IV, 30 days out: 50 × 0.30 × √(30/365) ≈ 50 × 0.30 × 0.287 ≈ $4.30. The market is pricing roughly a two-in-three chance the stock finishes between $45.70 and $54.30.
That calculation is worth doing before selling anything, because it converts an abstract percentage into the actual dollar range your strike is sitting inside. A $47 put on that stock is well within one standard deviation. That doesn't make it a bad trade; it makes it a trade whose likely path you can now describe.
Note the square root. Volatility scales with the square root of time, not with time, which is why a 60-day option doesn't carry twice the expected move of a 30-day one — it carries about 1.4 times.
Thirty percent IV is low for a small biotech and high for a utility. There's no absolute scale, so the raw figure is close to meaningless without a reference point.
That's what IV rank and IV percentile are for. Both compare today's implied volatility to the same stock's own range over the past year: rank places it between the year's low and high, percentile counts how many days sat below it. A stock at 30% IV with an IV rank of 90 is unusually expensive for itself. The same 30% with a rank of 10 is unusually cheap. Sellers care about the rank far more than the level.
When you sell an option you are, in effect, selling the market's estimate of future movement. If the stock ends up moving less than implied volatility said it would, the premium you collected was larger than the risk turned out to require, and the difference is yours.
Historically that gap has existed more often than not. Implied volatility tends to sit slightly above realized volatility, and the spread between them has a name: the volatility risk premium. It's the structural reason option selling has paid over long periods.
But it's worth being clear about why it exists. Someone has to be willing to hold the risk of a crash, and people pay above fair value to hand that risk off. Collecting the premium means you're the one holding it. The premium isn't an inefficiency you spotted; it's a fee for a service, and the service gets called in during exactly the weeks you'd rather it didn't.
This is the practical takeaway and it runs against the instinct. When you scan for the highest premium relative to strike, you are scanning for the highest implied volatility, which is to say you are scanning for the situations where the market most expects a large move.
Elevated IV usually has a cause: earnings in nine days, a pending trial result, a court date, a sector in the middle of a repricing. The premium is high because the risk is high, and it's high in roughly the right proportion most of the time. "Why is this one paying so much more than the others" is a research question, not a green light.
One consequence worth knowing before your first earnings trade. Implied volatility rises into a scheduled event because the outcome is unknown, then collapses the moment it's known — the uncertainty the premium was pricing has simply stopped existing.
For a buyer this is brutal: you can be right about direction, watch the stock move your way, and still lose money, because the volatility component of your option's price evaporated overnight. For a seller it's the mechanism behind selling premium into earnings, and it works until the move is larger than the premium, which is the day that erases several quarters of it working.