Put Option Cost Calculator

Put options provide downside protection - right to sell at strike price regardless of market price. Essentially insurance for stock holdings. Annual cost typically 2-8% of stock value depending on volatility, time to expiry, and strike distance from current price.

Example: own 1,000 shares at 50 = 50,000 stock value. Buy 10 put contracts (1 contract = 100 shares) at 45 strike for 1.50 premium per share = 1,500 total cost. Insurance cost = 3% of stock value for 30 days. Annualised cost = 36.5%. Stock above 45 at expiry: option expires worthless, you keep stock. Stock below 45: exercise put, sell at 45 (limit losses to 6.50/share including premium).

Put protection trade-offs: insurance has cost (drags returns 1-3%/year). Long-only buy-and-hold typically beats hedged portfolios over 10+ years. Best uses: protecting concentrated positions before earnings/known events, hedging during overvalued markets, near-retirement portfolios where loss tolerance low. Protection carries a cost: option buyers pay a volatility premium that, historically, sellers have tended to capture. That is the structural difference between buying premium (puts) and selling premium (covered calls).

Quick example

With current stock price of 50 and put strike price of 45 (plus premium per share of 1.5 and number of contracts of 10), the result is 1,500.00. Change any figure and watch the output shift — it's often more useful to see the pattern than to memorise the formula.

Which inputs matter most

You enter Current Stock Price, Put Strike Price, Premium Per Share, Number of Contracts, and Days to Expiry.

What's happening under the hood

Total cost = premium × shares (100 per contract). Annualised cost = cost % × 365/days. The formula is listed in full below. If the number looks off, you can retrace the calculation by hand — that's the point of showing the working.

Where this fits in planning

This is a "what-if" tool, not a forecast. It helps to test ideas: what happens if one of the inputs comes in higher or lower than you first assumed. The value is in the scenarios you run, not the single answer you get from the defaults.

What this doesn't capture

This is a simplified model that holds its assumptions constant. Real outcomes vary with market conditions, costs, taxes, and timing, so the figure is best read as one scenario rather than a forecast.