Contract size is the number of shares a single options contract represents — almost always 100 for standard equity options. Contract quantity is how many contracts you trade. Together, these two numbers determine your total exposure and the cost of any options position.
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 with a strike price of $50, for a premium of $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.
When contract size isn't 100 shares
The 100-share multiplier is the standard for equity options, but it isn't a hard rule. A few situations change it:
Adjusted options: after a stock split, merger, or special dividend, an existing contract can be adjusted so it covers a different number of shares or a mix of shares and cash. The ticker usually gets a marker to flag that it's non-standard.
Index and futures options: these don't settle into 100 shares. They use their own multiplier set by the exchange, so the same premium can translate into a very different dollar amount.
Smaller-size contracts: some markets list mini or reduced-size contracts that represent fewer units than the standard, which lowers the cost to get exposure.
The takeaway: before you trade, check the contract's stated multiplier rather than assuming it's always 100. That one number changes both your cost and your exposure.
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.