Cash-Secured Put Calculator
Free, no login · By OptionClaws · Updated 2026-09-28
A cash-secured put is a short put backed by enough cash to buy the shares if you are assigned. Enter the stock price, the put's strike and premium, and the days to expiration to see how much cash the trade ties up, what it returns on that cash, the annualized return, your breakeven and effective purchase price, and a model-based probability of profit. The math runs in your browser on the numbers you enter.
Illustrative inputs; enter your own. Results are calculated in your browser from the numbers you enter.
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The OptionClaws scanner runs this same math on real option chains and ranks every candidate by return, probability, and liquidity.
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How to use the cash-secured put calculator
- Enter the current stock price.
- Enter the put's strike and the premium per share you expect to collect. Use the bid or mid from your broker's option chain.
- Enter the days to expiration and the put's implied volatility. The volatility affects only the probability of profit and the premium estimate button.
- Set the number of contracts. Each contract secures 100 shares, so the cash reserved is the strike times 100 per contract.
- Compare the two return figures: return on the cash reserved, and the scanner's return on risk, which uses strike minus premium as the base.
How it's calculated
A short put pays the premium up front and obliges you to buy 100 shares at the strike if the stock finishes below it. At expiration the profit or loss per share is the premium minus the put's intrinsic value, max(strike minus final price, 0). The calculator uses the same payoff and probability functions as the OptionClaws scanner.
Two return conventions are common for this trade, and the calculator shows both so the numbers line up with whatever you compare them to. Return on cash reserved divides the premium by the full strike. Return on risk, the figure the scanner ranks cash-secured puts by, divides the premium by strike minus premium, the most you could lose.
- Cash reserved: strike times 100 per contract.
- Return on cash reserved: premium divided by strike. Annualized by multiplying by 365 over days to expiration.
- Max profit: the premium times 100, kept if the stock finishes at or above the strike.
- Max loss: (strike minus premium) times 100, if the stock goes to zero.
- Breakeven: strike minus premium, which is also your effective purchase price if assigned.
- Return on risk: premium divided by (strike minus premium); annualized return is that times 365 over days to expiration.
- Reg-T margin, for comparison: the requirement if the same put were sold on margin instead of secured with cash, from the options margin calculator's formula.
- Probability of profit: the lognormal-model chance the stock finishes above the breakeven, at your implied volatility and a 4.5% risk-free rate.
Assumptions and limitations
- Results are at expiration only; before then the put's value includes time value the chart does not show.
- The probability of profit is a model estimate, not a prediction.
- Early assignment is ignored. American-style puts that are deep in the money can be assigned before expiration.
- Fees, commissions, taxes, dividends, and interest earned on the reserved cash are not included.
- Premiums are taken as entered; the starting values are illustrative estimates, not quotes.
Frequently asked questions
- How much cash do I need for a cash-secured put?
- The strike times 100 for each contract. A $95 put needs $9,500 per contract reserved. Some brokers let the premium you receive count toward it, which brings the net cash down to strike minus premium.
- How is the return on a cash-secured put calculated?
- Premium divided by the cash reserved. A $1.30 premium on a $95 strike is about 1.37% for the trade; times 365 over 30 days is about 16.7% annualized, before fees and without compounding.
- Why are there two different return numbers?
- Return on cash reserved uses the full strike as the base. Return on risk uses strike minus premium, because the premium you collect offsets part of the worst case. The OptionClaws scanner ranks cash-secured puts by the second one, so both are shown.
- What happens if the stock finishes below the strike?
- You are assigned and buy 100 shares per contract at the strike, using the reserved cash. Your effective cost is the strike minus the premium. Many traders then sell covered calls on those shares.
- How is this different from a naked put?
- Same option and same payoff; different collateral. A naked put is held on margin, which reserves only a fraction of the strike, so its return percentage is much higher while the dollars at risk are the same. The options margin calculator shows that requirement.
Related
For education only, not investment advice. Results are model-based estimates from the inputs you enter and exclude fees, early assignment, and dividends. Options involve substantial risk and are not suitable for every investor. See our Terms of Service.