Bull Put Spread Calculator

A bull put spread (also called a put credit spread) is a bullish vertical spread where you sell a put at a higher strike and buy a put at a lower strike, both with the same expiration. You receive a net credit to enter, which is also your maximum profit.

Compared to selling a naked put at the same strike, you collect less premium—but your downside is capped rather than growing linearly as the stock price falls to zero. The bull put spread is also one half of a short iron condor, which combines it with a bear call spread above the stock price.

Key Characteristics

• Maximum Profit: Net credit × 100 × number of contracts. Achieved when the stock closes at or above the short strike at expiration.
• Maximum Loss: (Spread width − net credit) × 100 × number of contracts. Occurs when the stock closes at or below the long strike at expiration.
• Breakeven: Short strike − net credit.
• Best Used When: Moderately bullish or neutral, expecting the stock to stay above the short strike.

How to Read the Bull Put Spread P/L Chart

The white line (expiration) shows your profit/loss at expiration. When the stock finishes above the short strike, both puts expire worthless—you keep the full credit because the premium you collected from selling the short put exceeds what you paid for the long put. As the stock moves between the strikes, your profit shrinks because the short put starts to have intrinsic value while the long put remains worthless. Below the long strike, your loss is capped—the long put gains value dollar-for-dollar with the short put, protecting you from further downside.

The cyan line (T+0) shows your theoretical P/L today. Before expiration, the curve is smoother because both options retain time value. Time decay works in your favor when the stock is above your breakeven—T+0 sits below the expiration line in this region. However, if the stock falls toward or below your long strike, time decay works against you (negative theta) because you now need the long put's protection, and its time value is eroding.

How to Use This Calculator

Enter various spread details into the inputs:

1. Stock Price: Current price of the underlying stock
2. Short Strike: The higher strike where you sell the put
3. Long Strike: The lower strike where you buy the put
4. Days to Expiration: Time remaining until both options expire
5. IV or Prices: Enter implied volatility to calculate theoretical prices, or toggle to Calculate with Prices to enter actual prices for each leg

Then change the inputs to see how the spread metrics change (shift strikes further ITM or OTM, change IV, etc.). You can learn a lot about the strategy by experimenting with the inputs.

When to Use a Bull Put Spread

Bull put spreads work well when you're moderately bullish or neutral and want to collect premium with defined risk. If you think a $100 stock will stay above $95 but probably won't rally hard, a bull put spread lets you profit from that stability. The tradeoff: if the stock does rally hard, your profit is capped at the credit received—unlike a long call or long stock, which can capture unlimited upside.

Why Bull Put Spreads Are High Probability Trades

Because you receive a net credit for the spread, your breakeven is below the current stock price in most cases (unless you're selling an ITM spread). The position makes money if the stock rallies, stays flat, or even drops slightly—as long as it remains above your breakeven at expiration.

Bull Put Spread vs Bull Call Spread

Both are bullish strategies with limited risk and profit potential. A bull call spread is a call spread you pay to enter, while a bull put spread is a put spread you receive premium to enter. At the same strikes and expiration, these positions are synthetically equivalent—they have nearly identical max profit, max loss, and breakevens.

The difference comes down to which options are OTM. Traders typically sell OTM options for better liquidity and to avoid early assignment. If you're betting the stock stays above a certain price, you'd sell an OTM put spread (bull put spread). If you expect a stronger move higher, you'd buy an OTM call spread (bull call spread).

You generally wouldn't buy a deep ITM call spread due to assignment risk and wider bid-ask spreads—you'd sell a put spread at the same strikes instead. Conversely, you wouldn't sell a deep ITM put spread to play a move higher—you'd buy a call spread at the same strikes.

Bull Put Spread Assignment Risk

While rare, the short put in your spread can be assigned early—typically when it's deep in-the-money near expiration. If assigned, you'll be long 100 shares, but your long put protects you. You can exercise your long put to sell the shares, or sell the shares while closing the long put, effectively closing the spread at max loss less any additional fees.