Volatility: If an options market is highly volatile (i.e. if its daily price range is large), the premium will be higher, because the option has the potential to make more profit for the buyer. Conversely, if an options market is not volatile (i.e. if its daily price range is small), the premium will be lower. An options market's volatility is calculated using its long-term price range, its recent price range, and its expected price range before its expiration date, using various volatility pricing models.
* Sell orders are subject to an activity assessment fee (from $0.01 to $0.03 per $1,000 of principal). Trades are limited to online domestic equities and options and must be used within two years. Options trades are limited to 20 contracts per trade. Offer valid for new and existing Fidelity customers opening or adding net new assets to an eligible Fidelity IRA or brokerage account. Deposits of $50,000-$99,999 will receive 300 free trades, and deposits of $100,000 or more will receive 500 free trades. Account balance of $50,000 of net new assets must be maintained for at least nine months; otherwise, normal commission schedule rates may be retroactively applied to any free trade executions. See Fidelity.com/ATP500free for further details and full offer terms. Fidelity reserves the right to modify these terms and conditions or terminate this offer at any time. Other terms and conditions, or eligibility criteria may apply.
Just as you can buy a stock because you think the price will go up or short a stock when you think its price is going to drop, an option allows you to bet on which direction you think the price of a stock will go. But instead of buying or shorting the asset outright, when you buy an option you’re buying a contract that allows — but doesn’t obligate — you to do a number of things, including:
A longer expiration is also useful because the option can retain time value, even if the stock trades below the strike price. An option’s time value decays as expiration approaches, and options buyers don’t want to watch their purchased options decline in value, potentially expiring worthless if the stock finishes below the strike price. If a trade has gone against them, they can usually still sell any time value remaining on the option — and this is more likely if the option contract is longer.
The price at which you agree to buy the underlying security via the option is called the "strike price," and the fee you pay for buying that option contract is called the "premium." When determining the strike price, you are betting that the asset (typically a stock) will go up or down in price. The price you are paying for that bet is the premium, which is a percentage of the value of that asset. 
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