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What an option actually is

Calls, puts, premium, and why one contract controls 100 shares.

9 min · Beginner · Free lesson

What you'll learn

Explain the difference between a call and a put in plain language
Convert a quoted premium into the real dollar cost of one contract
Calculate profit, loss and breakeven at expiration for a simple long call and long put

The idea

An option is a contract that gives you the right, but not the obligation, to buy or sell a stock at a set price before a set date. You pay a price for that right. That price is called the premium.

There are only two kinds. A call gives you the right to buy the stock at the set price. You buy calls when you think the stock is going up. A put gives you the right to sell the stock at the set price. You buy puts when you think the stock is going down.

Think of a call like a non-refundable deposit on a house. You pay a small amount today to lock in the purchase price. If the neighborhood gets hot and prices rise, your locked-in price is valuable. If prices fall, you walk away and lose only the deposit. That is the core deal of buying an option: a limited, known cost for a shot at a larger move. The catch is that the deposit has an expiration date, and if nothing happens in time, it is simply gone.

How it works

One contract = 100 shares. US equity options are standardized. One contract controls 100 shares of the underlying stock.
Premium is quoted per share. If a quote says $2.50, one contract costs $2.50 x 100 = $250. Always multiply by 100 before you think about dollars.
Strike price is the locked-in price. Expiration is the last day the contract exists.
Buyer vs seller. The buyer pays the premium and gets the right. The seller collects the premium and takes on the obligation to deliver (calls) or buy (puts) the shares if assigned. When you buy an option, your maximum loss is the premium you paid.
You rarely exercise. Most US equity options are American-style, meaning they can be exercised any time before expiration. In practice, most traders simply sell the option back to close the position before expiration.
Breakeven at expiration:

Long call: strike + premium
Long put: strike - premium

Worked example

Hypothetical stock XYZ trades at $50. You believe it can move higher over the next month.

Option A: buy 100 shares. Cost: $5,000.

Option B: buy 1 XYZ $50 call, 30 days to expiration, premium $2.00. Cost: $2.00 x 100 = $200.

Now look at expiration day:

XYZ closes at $56. The call lets you buy at $50 a stock worth $56, so it is worth $6.00, or $600. Your profit is $600 - $200 = $400, a 200% return on premium. The share buyer made $6 x 100 = $600, a 12% return on $5,000.
XYZ closes at $52. The call is worth $2.00, exactly what you paid. This is your breakeven: $50 strike + $2.00 premium = $52.
XYZ closes at $49. The call gives you the right to buy at $50 a stock worth $49. Nobody wants that. It expires worthless and you lose the full $200. The share buyer is down only $100.

Notice the trade-off. The option buyer risked less money and made a bigger percentage return when right, but lost 100% of the premium on a small move the wrong way. The stock was close, but close does not pay at expiration.

A put example. You think XYZ at $50 will fall. You buy 1 XYZ $50 put for $1.80, costing $180. At expiration:

XYZ at $44: the put lets you sell at $50 a stock worth $44, so it is worth $6.00 ($600). Profit = $600 - $180 = $420.
Breakeven = $50 - $1.80 = $48.20.
XYZ at or above $50: the put expires worthless. Loss = $180.

Common mistakes

Forgetting the 100 multiplier — a "$3 option" is really $300 per contract, and five contracts is $1,500 — always write the dollar cost before you place the order.
Thinking "right direction" means profit — at expiration you need the stock beyond your breakeven, not just past the strike — calculate breakeven before you enter.
Treating cheap options as low risk — a $0.20 option can and often does go to zero — judge risk by the dollars you can lose, not the price per share.
Confusing buying and selling — selling an option you do not own creates an obligation with much larger risk — as a beginner, stick to defined-risk long options until later lessons.

Checklist

Do I know whether I am buying a call (bullish) or a put (bearish)?
Have I multiplied the premium by 100 to get my real cost?
Is my maximum loss (the full premium) an amount I accept losing?
Do I know my breakeven price at expiration?
Do I know the expiration date and how much time the idea needs?

Practice: Price three contracts in dollars

Open Paper Sim and pull up the options chain for SPY or AAPL.
Pick one call and one put near the current stock price and write down each premium.
Convert each premium into the dollar cost of one contract and calculate each breakeven at expiration.
Write in your Trade Journal what stock price each option needs at expiration to make $100 profit.
Ask the AI Coach to check your math before you place any paper trade.

Key takeaways

A call is the right to buy at the strike; a put is the right to sell at the strike.
One US equity option contract controls 100 shares, so a $2.50 premium costs $250.
When you buy an option, your maximum loss is the premium you paid.
Breakeven at expiration is strike plus premium for a long call and strike minus premium for a long put.
Options give leverage in both directions: bigger percentage wins, but a full loss if the move does not come in time.

Glossary

Premium — The price of an option, quoted per share; multiply by 100 for the cost of one contract.
Call — A contract giving the buyer the right to buy 100 shares at the strike price before expiration.
Put — A contract giving the buyer the right to sell 100 shares at the strike price before expiration.
Breakeven — The stock price at expiration where the option trade neither makes nor loses money.

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