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Cash-Secured Put Calculator
Enter the stock price, put strike, premium and days to expiry.
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Cash-secured put calculator
Today’s price
Where you would buy
Calendar days, 1 to 1,825
100 shares each
- The term is 30 days, under 60. The annualised figure stretches a short period across a year, so use it only to compare contracts.
- Monthly yield
- 1.49%
- Annualised yield
- 18.19%
Scaled to 30 days. The same figure as Monthly Yield % in the Matrix.
Comparison scale only: assumes the same trade repeats for a year.
Monthly yield 1.49%. Annualised yield 18.19%. Breakeven $95.55.
- Cash set asideStrike × 100 × contracts
- $9,700.00
- Premium received
- $145.00
- Return over 30 daysPremium ÷ strike
- 1.49%
- Breakeven and effective purchase priceStrike minus premium, per share
- $95.55
- Breakeven vs today’s price
- 4.45% below
- Strike vs today’s price
- 3.00% below
- Loss if the stock goes to $0
- $9,555.00
Educational and informational only. Figures are simple calculations before commissions and taxes, and are not financial advice. Check the contract details with your broker.
How it is calculated
- Cash set aside
strike × 100 × contractsThe collateral. The Matrix uses the strike as the capital for a put.
- Return on collateral
premium ÷ strikeThe premium as a share of the cash you hold.
- Monthly yield
return on collateral × 30 ÷ days to expiryThe Monthly Yield % formula from the Matrix in Options Matrix Pro: any expiry scaled to 30 days.
- Annualised yield
return on collateral × 365 ÷ days to expirySimple, not compounded. A comparison scale only.
- Breakeven
strike − premiumAlso the effective purchase price per share if you are assigned.
- Maximum loss
(strike − premium) × 100 × contractsWhat the position loses if the stock goes to zero.
Assumptions
- Collateral is the full strike price in cash. A margin account may need less, which changes the return on the capital you commit.
- Returns are simple and shown before commissions and taxes. Interest earned on the cash is not included.
- The premium is per share, and one contract covers 100 shares.
- An American-style put can be assigned before expiry, so the purchase can happen earlier than the expiry date.
- Annualised figures assume the same trade repeats every period for a year. Premiums change, so they are a comparison scale and not a forecast.
Worked example
You sell one $97.00 put on a $100.00 stock with 30 days to expiry and collect $1.45 a share. “Reset to example” loads these numbers into the calculator.
| Result | Working | Value |
|---|---|---|
| Cash set aside | $97.00 × 100 × 1 | $9,700.00 |
| Premium received | $1.45 × 100 × 1 | $145.00 |
| Return over 30 days | $1.45 ÷ $97.00 | 1.49% |
| Monthly yield | $1.45 ÷ $97.00 × 30 ÷ 30 | 1.49% |
| Annualised yield | $1.45 ÷ $97.00 × 365 ÷ 30 | 18.19% |
| Breakeven and effective purchase price | $97.00 − $1.45 | $95.55 |
| Breakeven below today’s price | ($100.00 − $95.55) ÷ $100.00 | 4.45% |
| Loss if the stock goes to $0 | ($97.00 − $1.45) × 100 × 1 | $9,555.00 |
Reading the result
Scale first, then compare
A 7-day put and a 45-day put are not comparable on raw premium. The monthly yield puts them on one 30-day scale. Check the breakeven distance and the probability next.
Yield and risk rise together
A higher monthly yield usually comes from a strike closer to the stock price or from higher implied volatility. Both raise the chance of assignment. The probability of profit calculator puts a number on it.
Assignment is a purchase
If the put finishes in the money you buy 100 shares per contract at the strike. The breakeven is your effective cost after the premium.
Frequently asked questions
How do you calculate the return on a cash-secured put?
Divide the premium by the strike price. A $1.45 premium on a $97.00 strike returns 1.49% on the $9,700.00 you set aside. Multiply by 30 and divide by the days to expiry for the monthly yield.
How much cash do I need to secure a put?
The strike price times 100 for each contract, so a $97.00 strike needs $9,700.00 per contract. Some brokers accept less on margin. This calculator uses the full amount, which is how Options Matrix Pro sizes a put.
What is the breakeven on a cash-secured put?
The strike minus the premium: $97.00 − $1.45 = $95.55 here. It is also what you effectively pay per share if you are assigned, before fees.
Why is the annualised yield so much larger than the period return?
It multiplies the period return by 365 ÷ days. With 30 days that is about 12.17 times, so 1.49% becomes 18.19%. It is not what you will earn. Premiums move with volatility, and assignment changes the position.
Can a short put be assigned before expiry?
Yes. Puts on stocks and ETFs are usually American style, so the buyer can exercise at any time and you can be assigned early. You then buy the shares at the strike sooner than planned and the premium you collected stays yours. Early assignment is most likely when the put is deep in the money and has little time value left.
Go further
Compare every strike and expiry for a symbol
The Options Yield Matrix ranks one symbol’s contracts by Monthly Yield %, with probability of profit and position size beside each. It is included in Pro ($30/month) and All Access ($50/month).