Before you place an options trade, two numbers matter more than most: contract size and contract quantity. Together, they determine how much you're spending and how much exposure you're taking on. Get comfortable with both, and the math behind any options position becomes a lot clearer.
Contract size (the multiplier)
Contract size — also called the multiplier — is the number of shares a single options contract represents. For standard equity options, that number is almost always 100.
That means when you buy one call option, you're not buying the right to purchase one share. You're buying the right to purchase 100 shares at the strike price. Same goes for puts — one contract gives you the right to sell 100 shares.
Contract quantity
Contract quantity is simply how many options contracts you buy or sell in a trade. Buy two call options? Your quantity is two. That gives you the right to buy 200 shares (2 contracts × 100 multiplier).
More contracts means more exposure — and more cost.
A real example (with fake numbers)
Let's say you buy one PEAR contract that expires in April and has a strike price of 50 for $2.50.
To find the total cost of the trade, multiply the premium by the contract multiplier and the quantity:
$2.50 × 100 × 1 = $250 (before fees and commissions)
That's it. One contract, 100 shares of exposure, $250 out of pocket.
If you bought five contracts instead of one, the math scales directly:
$2.50 × 100 × 5 = $1,250
Why this matters: leverage
Here's where it gets interesting. PEAR is trading at $50 per share. If you wanted to buy 100 shares outright, it would cost you $5,000. But with one call option, you get exposure to those same 100 shares for just $250.
That's leverage — and it's one of the defining features of options trading. You're controlling a large number of shares for a fraction of the cost of buying them directly.
Leverage can work in your favour when a trade goes well. But it can also amplify losses when it doesn't. The key is knowing your potential profit and loss before you enter any position — not after.
Putting it all together
Contract size and quantity are the foundation of options math. Every calculation — total cost, max profit, max loss, break-even — starts here. Once you have these two numbers down, the rest follows naturally.