Get paid while you wait to buy a stock cheaper. Enter the strike, premium and days to expiration to see the cash you must set aside, your breakeven, and the annualized yield on that collateral.
Answer first: selling a cash-secured put means you promise to buy 100 shares at the strike price if the stock falls there by expiration, and you set aside the full cash to honor it. In exchange you collect a premium immediately. This calculator shows the collateral you must park (strike × 100 per contract), your breakeven (strike minus premium — also your effective purchase price if assigned), and the yield that premium earns on your collateral, annualized for comparison.
Collateral = strike × 100 · Breakeven = strike − premium · Yield = premium ÷ strike
Example: sell a 30-day $45 put for $1.20 → set aside $4,500, breakeven $43.80, premium yield 2.67% in 30 days ≈ 32.4% annualized.
| At expiration | What happens | Your result |
|---|---|---|
| Stock above the strike | Put expires worthless | Keep the premium; collateral is freed |
| Stock below the strike | Assigned: you buy 100 shares at the strike | Own the stock at an effective cost of strike − premium |
That second row is the point most beginners miss: assignment is not a failure mode — it is half of the strategy. Sell puts only at strikes where you would be genuinely happy to own the shares, on companies you already want. Then either outcome is acceptable: income if the stock stays up, a discounted entry if it drops.
Below the breakeven, a cash-secured put loses money almost exactly like owning the stock from the strike price. If the shares collapse from $50 to $30, you are buying at $45 with a $1.20 consolation prize — a $13.80-per-share paper loss on day one of ownership. The premium is real income, but it is compensation for accepting that risk, not free money. Fat premiums mean the market expects big moves; the yield is the warning label.
Cash-secured puts are the first half of the popular “wheel” strategy: sell puts until assigned, then sell covered calls on the assigned shares until they are called away, and repeat. Each leg collects premium; this calculator and its covered-call twin let you price both legs before committing.
Reality check: annualized yields assume you can redeploy at identical terms every cycle, which markets rarely allow. Figures exclude commissions, and early assignment is possible. A put is “cash-secured” only if the cash truly sits there — selling puts on margin is a different, riskier trade. Educational tool only — not financial advice.
Compare with the covered call calculator, check payoff shapes in the options profit calculator, learn the vocabulary in options Greeks explained, and try the mechanics risk-free in the options trading game.
Last updated July 2, 2026 · Written by Mustafa Bilgic. Educational only — not financial advice.
You sell a put option while holding enough cash to buy 100 shares at the strike if assigned. You keep the premium either way; if the stock falls below the strike you buy it at an effective price of strike minus premium.
Strike price × 100 per contract. A $45 strike requires $4,500 of collateral per contract set aside until expiration or assignment.
Strike minus premium. Selling a $45 put for $1.20 gives a breakeven of $43.80 — below that the position loses money, above the strike you simply keep the premium.
It is a slightly cushioned version of the same downside: below breakeven you lose almost like a shareholder. It is safer only in the sense that the premium lowers your entry price.
A repeating cycle: sell cash-secured puts until assigned shares, then sell covered calls on those shares until they are called away, collecting premium at every step.