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Diagonal Spread Calculator

Model your diagonal spread before you place it. Enter your long and short strikes and premiums to instantly see max profit, max loss, breakeven, and a full P&L diagram.

Different Strikes & Expirations Directional Bias Defined Max Loss Interactive P&L Diagram
Black-Scholes-Merton pricing with dividend yield; American-style early exercise available below.

Underlying Asset

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Strategy Template (optional, pre-fills legs below)

Option Legs

Implied volatility is solved automatically from the premium you enter (still editable). Legs with different expirations are supported (calendar spreads). Fetch a price above to pick strikes and premiums from the live option chain.

Getting Started

How to Use This Calculator

Four inputs and the calculator handles the rest. Results update instantly as you type.

1

Pull current market data (optional)

Type a ticker like AAPL and click Get Price. The calculator fills in the current stock price, dividend yield, and the risk-free rate from the 13-week T-bill, then loads the option chain so you can pick actual strikes and premiums.

2

Set up your diagonal spread legs

The diagonal spread legs are preloaded for you. Pick each strike, expiration, and premium straight from the option chain, or type your own numbers. The calculator works out implied volatility from the premium you enter, and you can still edit it.

3

Calculate and read the results

Click Calculate P&L to see max profit, max loss, breakeven, return on risk, and probability of profit, plus position Greeks: delta, gamma, theta, vega, and rho.

4

Stress test before you trade

Drag the view-date slider to see your P&L curve on any day before expiration, shift implied volatility up or down 50 points, and scan the price-by-date P&L table to see how the trade behaves across scenarios.

This diagonal spread calculator prices each leg with your choice of an American-style binomial model (the default for US equity options) or European Black-Scholes-Merton, and accounts for dividend yield. You can set a per-contract commission, copy a shareable link to your exact setup, download the chart as a PNG, and switch to dark mode.

Strategy Breakdown

Understanding the Diagonal Spread

Key numbers every diagonal spread trader needs to know before entering the position.

Max Profit
(Short Strike − Long Strike) − Net Debit
Achieved when the stock closes at or above the short call strike at front-month expiration. The spread reaches its maximum value when the full width is captured minus the net debit you paid to enter.
Max Loss
Net Debit Paid
Occurs if the stock drops sharply and both options expire worthless, or if the spread collapses in an unfavorable environment. Your loss is fully capped at what you paid to enter the position.
Breakeven at Expiration
Long Strike + Net Debit
The approximate stock price at which the position breaks even at the short option’s expiration. The exact level varies with implied volatility and time remaining in the back-month option at expiration.

The diagonal spread earns its name from the way it appears on an options chain: moving diagonally across both the strike column and the expiration column. By combining different strikes and different expirations, the strategy layers a directional view on top of a time decay structure. The short front-month option decays faster than the long back-month option, giving you a built-in theta advantage while you wait for the stock to move in your favor.

For a bullish call diagonal, you want the stock to drift higher and close near or above the short call strike at front-month expiration. If it does, the short call expires worthless, you capture the full premium, and the long back-month call has appreciated in value. You can then sell another short-term call against the remaining long leg, repeating the cycle to reduce your net debit further each expiration.

One important check before entering any diagonal: confirm that the spread width (short strike minus long strike) is greater than the net debit. If the spread width is less than the net debit, the maximum profit would be negative, making the trade not worth taking at those prices.

Worked Example

Diagonal Spread Example Trade

XYZ is trading at $100. You buy a 60-day $95 call for $8.00 and sell a 30-day $105 call for $2.00.

Position Summary (Call Diagonal)
Stock Price$100.00
Long Call Strike (60-day)$95.00
Long Call Premium Paid−$8.00 / share (−$800)
Short Call Strike (30-day)$105.00
Short Call Premium Received+$2.00 / share (+$200)
Net Debit−$6.00 / share (−$600)
Spread Width$10.00 ($105 − $95)
Max Profit~+$400 (if stock ≥ $105 at 30-day expiry)
Max Loss−$600 (net debit)
Breakeven~$101.00 ($95 + $6.00)
After Short Expires WorthlessStill hold 30-day $95 call — sell another short-term call
Pitfalls

Common diagonal spread mistakes to avoid

A diagonal spread runs on two different expirations and a built-in management cycle, and most of the damage happens when one of those moving parts gets ignored. These are the errors that show up most often.

1. Entering when the spread width is smaller than the net debit

Max profit on a call diagonal is the short strike minus the long strike, minus the net debit paid. If the width between strikes is smaller than the debit, the best-case outcome is a loss before the trade even starts. Check that math against the actual quoted prices before entering, not just the general shape of the trade.

2. Not watching the short call for early assignment

The short front-month call is a normal American-style option and can be assigned early, especially once it moves deep in the money or ahead of an ex-dividend date on the underlying. Getting assigned means delivering shares you do not own outright, since the long leg is a different contract with a later expiration. Track the short call’s extrinsic value, not just its strike.

3. Underestimating how differently the two legs react to IV

The long back-month option carries more vega than the short front-month option, so it is more sensitive to changes in implied volatility. A drop in IV after entry can shrink the long leg’s value by more than the short leg gives back, even if the stock price barely moves. Check implied volatility on both legs, not just the stock’s direction, before sizing the trade.

4. Letting the short call expire without rolling it

The theta advantage in a diagonal spread comes from repeatedly selling short-term premium against the long-dated leg. If the front-month short call expires and a new one is not sold against the remaining long call, the position quietly turns into a plain long call financed at a worse price than buying one outright would have been.

5. Spacing the strikes so wide the short call rarely gets tested

Placing the short strike far above the long strike lowers the premium collected each cycle, since further out-of-the-money options carry less extrinsic value. A diagonal built this way compounds theta more slowly and behaves closer to a discounted long call than the income-generating structure the strategy is meant to be.

6. Choosing a diagonal when a simpler structure covers the same goal

Managing two expirations and two strikes adds real complexity, and it only pays off if the roll cycle is something you plan to actually manage. If the goal is financing a long-term bullish position with short-term premium without picking a second strike from scratch, the poor man’s covered call calculator models the same long-call-plus-short-call mechanics with a strike structure built specifically for that goal.

All strategies

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Each strategy has its own dedicated calculator with a full P&L breakdown, worked example, and FAQ.

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FAQ

Diagonal Spread — Common Questions

A diagonal spread is an options strategy that uses different strike prices and different expiration dates. You buy a longer-dated option at one strike and sell a shorter-dated option at a different strike, blending the time decay benefit of a calendar spread with the directional exposure of a vertical spread. The most common version is a bullish call diagonal: buy a lower-strike back-month call and sell a higher-strike front-month call. A bearish put diagonal works in the opposite direction. The poor man’s covered call is a well-known example of a call diagonal spread.
The maximum profit on a call diagonal spread is approximately the spread width (short strike minus long strike) minus the net debit paid. For example, with a $95 long call and a $105 short call, the spread width is $10. If the net debit is $6.00, max profit is roughly $4.00 per share, or $400 per contract. This is achieved when the stock closes at or above the short call strike at front-month expiration. The exact figure varies with implied volatility and the time value remaining in the back-month option at expiration.
The maximum loss on a diagonal spread is the net debit paid to enter the position. This occurs when the stock falls sharply and both options expire worthless, or when the spread collapses to near zero in an unfavorable scenario. For example, if your net debit is $6.00 per share, your maximum loss is $600 per contract. Because diagonal spreads are entered for a net debit, risk is fully defined from the moment you place the trade.
The approximate breakeven on a call diagonal spread is the long call strike plus the net debit paid. For example, with a $95 long call and a net debit of $6.00, the breakeven is approximately $101.00. The exact breakeven depends on implied volatility and time remaining in the back-month option at expiration, so it is an estimate rather than a fixed price. The stock needs to be above the breakeven at the short option’s expiration for the trade to be profitable at that cycle.
A calendar spread uses the same strike price for both legs, differing only in expiration date. A diagonal spread uses both different strike prices and different expiration dates, giving it a directional component that a calendar spread lacks. A calendar spread profits most when the stock stays right at the shared strike. A diagonal spread can be structured to profit from a directional move — a bullish call diagonal profits when the stock rises toward or above the short strike, while a bearish put diagonal profits when the stock falls toward or below the short put strike.