How to use this calculator
- Enter the current share price and days to expiration.
- Enter the short put you sold - its strike and the premium received.
- Enter the long put you bought for protection - its strike and the premium paid.
- Set the number of contracts.
- Read the result: net credit, max loss, breakeven, return on risk, and how much downside cushion you have before the trade loses.
What it tells you: whether a put credit spread's credit is worth the capped loss you take if the stock falls through your strikes.
How this calculator works
A bull put spread has two legs in the same expiration: a put you sell at a higher strike, and a put you buy at a lower strike for protection. Because the higher-strike put is worth more, you take in a net credit. That credit is the most you can make; the gap between the strikes, less the credit, is the most you can lose.
Enter both strikes and both premiums and the calculator works out the three numbers that define the trade. Max profit is the net credit times 100 per contract, kept when the stock finishes at or above the short strike and both puts expire worthless. Max loss is the strike width minus the net credit, times 100, reached when the stock finishes at or below the long strike. Breakeven is the short strike minus the net credit per share — the price at which the trade is exactly flat at expiration.
From those it derives the return on risk (credit ÷ max loss), an annualized version of that figure, and how much downside cushion you have between today's price and the breakeven. The payoff diagram shows the whole shape: flat profit on the right, a sloped middle between the strikes, and flat loss on the left.
Bull put spread vs cash-secured put
Both are bullish-to-neutral ways to sell put premium, but they trade off premium against risk and capital. A cash-secured put has no protective leg: you collect more premium, but you carry the stock's full downside and must set aside the strike times 100 in cash. A bull put spread spends part of that premium on a lower-strike put, which caps the loss and slashes the capital required — often to a few hundred dollars per contract instead of several thousand.
The rule of thumb: if you would genuinely be happy to own the shares at the strike, the cash-secured put gives you the most premium and a path to the wheel. If you only want a defined, capital-efficient bullish bet and have no interest in assignment, the bull put spread is the cleaner tool.
Worked example
A fixed, hypothetical illustration — not live market data.
A hypothetical stock trades at $100. With 30 days to expiration you sell the $95 put for $2.10 and buy the $90 put for $0.90, for a net credit of $1.20 per share.
- Net credit / max profit: $1.20 × 100 = $120 per contract.
- Strike width: $95 − $90 = $5.
- Max loss: ($5 − $1.20) × 100 = $380 per contract.
- Breakeven: $95 − $1.20 = $93.80.
- Return on risk: $120 ÷ $380 ≈ 31.6% over 30 days.
- Cushion to breakeven: the stock can fall from $100 to $93.80 — about 6.2% — before the trade starts to lose.
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Common mistakes
- Choosing a width you can't afford to lose. A $10-wide spread risks roughly twice the dollars of a $5-wide one. Size the width to the loss you can take, not the credit you want.
- Chasing rich credits with deep in-the-money short strikes. A bigger credit usually means a higher chance of finishing at max loss. The credit is compensation for risk, not free money.
- Ignoring early assignment. A short put that goes deep in-the-money — especially near an ex-dividend date — can be assigned early, leaving you long stock before expiration.
- Misreading the annualized return. A two-week spread can annualize to triple digits; that is arithmetic, not an expected compounding rate.
- Forgetting commissions and fees. Two legs mean two sets of contract fees in and (if you close) out — material on small credits.
Frequently asked questions
What is a bull put spread?
A bull put spread (or put credit spread) is a two-leg options trade: you sell a put at a higher strike and buy a put at a lower strike in the same expiration. You collect a net credit, and your risk is capped at the difference between the strikes minus that credit. It profits when the stock stays above your short strike, so it is a bullish-to-neutral, defined-risk way to sell premium.
How is the max loss on a bull put spread calculated?
Max loss = (strike width − net credit) × 100 per contract, where the width is the short strike minus the long strike. It occurs when the stock finishes at or below the long (lower) strike at expiration, so both puts are in-the-money. The long put caps the loss — that is what makes the risk defined, unlike a naked short put.
What is the breakeven on a bull put spread?
Breakeven = short put strike − net credit per share. At expiration, if the stock is exactly at that price you neither make nor lose money. Above it you keep some or all of the credit; below it the position moves toward its max loss.
Bull put spread vs cash-secured put — which is better?
A cash-secured put has no long leg, so it collects more premium but carries the full downside of owning the stock and ties up far more capital (the strike × 100). A bull put spread buys a protective put, lowering the premium and the capital required and capping the loss. Choose the spread for defined risk and efficient capital; choose the cash-secured put when you would happily own the shares and want maximum premium.
When does a bull put spread make the most money?
Maximum profit — the full net credit — is reached when the stock closes at or above the short (higher) strike at expiration, so both puts expire worthless. You do not need the stock to rise; it only has to stay above the short strike.
Why is the annualized return so high?
Annualized return scales the return on risk by 365 ÷ days to expiration. Short-dated credit spreads (a few weeks) annualize to very large percentages because you are extrapolating a brief holding period across a whole year. Treat it as a way to compare trades of different lengths, not as a return you should expect to compound.
Can I lose more than the calculated max loss?
At expiration, no — the long put caps your loss. The two practical exceptions are early assignment on the short put (more likely when it is deep in-the-money or around an ex-dividend date) and pin risk near the strikes at expiration. Both are manageable, but they mean the real-world outcome can briefly differ from the textbook max loss.
When should I use a bull put spread?
When you are bullish-to-neutral but want defined risk and far less capital than a cash-secured put - you keep the credit if the stock stays above your short strike. It shines when implied volatility is elevated, fattening the credit, over a support level you trust. Skip it if you would rather own the shares (use a cash-secured put), and in a clear downtrend - selling puts into a falling knife only caps the pain.
Related tools and guides
Selling premium on both sides at once? See the Iron Condor Calculator. Prefer to be assigned the shares? Compare with the Cash-Secured Put Calculator. Map any multi-leg position with the Payoff Diagram Builder.
Check whether premium is rich first with the IV Rank Calculator, and look up any term in the options glossary. New to it? Start with What is a bull put spread? Deciding between strategies? Cash-Secured Put vs Bull Put Spread walks through when to pick each one.
Educational tool only. Nothing here is financial advice. Defined-risk spreads still lose money, and early assignment or pin risk can change the real-world outcome. Size positions accordingly.