What Is Contract Size? Definition & Example

Why It Matters

Contract size determines your actual dollar exposure. Standard = 100 shares. Getting this wrong means your position is 100x what you intended — or 1/100th.

How It Works

Standard US equity options: 100 shares. Mini options: 10 shares (limited availability). Nano options: 1 share (new, limited). Index options and futures options may have different multipliers.

Example

A $2.00 SPY put: standard contract = $200 cost, controls $58,000 of SPY exposure. A mini option at $2.00 = $20, controls $5,800. Same price per share, 10x different exposure.

Common Mistakes

Assuming all options are 100-share standard. Adjusted options after stock splits or special dividends can have non-standard contract sizes (e.g., 150 shares). Always check before trading adjusted contracts.

Related Terms

DTE (Days to Expiration)

Enter at 30–45 DTE for optimal theta/gamma balance. Close or roll at 21 DTE or 50% profit — whichever comes first.

Assignment

Not a disaster — it's the plan in the wheel strategy. If you only sell puts on stocks you'd own, assignment is just the next step.

Roll (Rolling)

Roll for a net credit or don't roll at all. Rolling for a debit just delays a loss. Best done before the position goes deep ITM.

Annualized Return

Looks impressive but is misleading if you ignore losses. Track actual account returns, not annualized returns on winners only.

Breakeven

Always know your breakeven before entering. If the stock can realistically reach it, either widen the margin or skip the trade.

Bid-Ask Spread

Wide bid-ask = hidden cost on every trade. Stick to liquid underlyings where the spread is under 5% of the option price.

Frequently Asked Questions