# Diagonal Spread Calculator - Profit & Breakevens Source: https://theoptionsbench.com/diagonal-spread-calculator/ > Plain-text mirror for AI/LLM ingestion. Canonical HTML page: https://theoptionsbench.com/diagonal-spread-calculator/ --- Diagonal spread - key facts A diagonal spread sells a near-dated option and buys a longer-dated one at a different strike - a calendar with a directional tilt, with the net debit as the defined max loss. Net debit (max risk) Long premium - short premium, × 100 - the cost to open and the most you can lose. Max profit Estimated at the short strike at the near expiry: the long leg's leftover value minus the debit (depends on the back-month IV). Breakeven A call diagonal has a lower breakeven, then stays profitable up; a put diagonal has an upper one, then stays profitable down. Direction A call diagonal leans bullish, a put diagonal bearish - unlike the market-neutral calendar. Nature Long vega and positive theta on the short leg - rising IV helps, a sharp adverse move hurts. Want the full explanation? Read What is a Diagonal Spread? . How to set it up Outlook: A slow drift your way, not a sprint: a Call Diagonal wants the stock grinding up, a Put Diagonal grinding down - and because you own more time than you sold, you want IV stable-to-rising, not crushing. Ideal DTE (short / long) Sell the near leg at 30-45 DTE so theta is biting; buy the far leg 2-3× further out (60-120 DTE) so it barely decays while the short rots. A PMCC stretches the long leg to a LEAPS. Close the DTE gap and it behaves like a vertical, not a diagonal. Strike selection Short strike out near the 30-delta line - roughly one expected move away, where you collect real premium but the stock has room to drift in before it pins you. Keep the strike width wider than the net debit, or you cap your own upside (Call) or downside (Put) before the trade can pay. LEAPS / long-leg delta (PMCC) If you run it as a Poor Man's Covered Call, buy the long call deep ITM at 0.80+ delta so it tracks the stock like shares. A 0.50-delta long leg is a lottery ticket, not a stock substitute - it lags the short call on a rally and bleeds time value. Enter when IV Rank low-to-moderate (roughly under 50) with room to rise. You're net long vega - you own more time than you sold - so a high-IV entry that mean-reverts down crushes the far leg harder than it helps the near one. This is the opposite of a premium-selling entry. Take profit Bank it at 25-50% of the debit you risked. The far leg's value at the near expiry is only a Black-Scholes estimate that swings with IV, so don't hold out for the modeled peak - a vol dip can erase a paper win that never settled. Manage / exit Close or roll the short leg at 50% of its premium OR 21 DTE, whichever hits first, to dodge late-cycle gamma - then resell against the still-alive long. Roll the tested side away (Call up, Put down) before the short goes deep ITM; an ITM short near an ex-dividend date is the classic early-assignment trap. Use it when: You have a direction AND a timeline - you expect a gentle drift your way over weeks while you finance it by selling decay against a longer-dated leg you keep. Skip it when: Your view is sharp and urgent (buy a Long Call or a vertical instead) or dead neutral (run a plain Calendar Spread) - and never hold the long leg through earnings, where the vol crush hits it hardest. Starting points, not rules - the conventions experienced sellers reach for first. Your account, thesis and risk move every number here. See every strategy's setup -> ## How to use this calculator - Enter the current share price, pick call or put diagonal, and set the implied volatility to assume at the near expiry. - Enter the long (far) leg - its strike, premium paid, and days to expiration. - Enter the short (near) leg - its strike, premium received, and days to expiration. - Set the risk-free rate and number of contracts. - Read the result: net debit (max loss), estimated max profit, breakeven(s), and return on debit - then re-run at a higher and lower IV to test the estimate. **What it tells you:** the estimated profit, defined risk, and breakeven of a diagonal spread at the near expiration, given your volatility assumption. ## How this calculator works A diagonal spread has two strikes and two expirations: you **sell** a near-dated option and **buy** a longer-dated one at a different strike. Because the longer leg holds more time value, you pay a net debit to open - and that debit is the most you can lose. At the near expiration the far leg is still alive, so its worth is not a fixed intrinsic number - it depends on the time and implied volatility left. The calculator prices that far leg with the Black-Scholes model, using the IV you enter and the days remaining, then subtracts the intrinsic value of the near option you have to buy back and the debit you paid. That gives the estimated P&L at every price, from which it reads the **estimated max profit** (at the short strike), the **breakeven(s)**, the **return on debit** and the **max loss**. ## Why the breakeven is often one-sided This is the big difference from a calendar. A call diagonal whose strike width is larger than the net debit has a **single lower breakeven**: once the stock clears it, the position stays profitable all the way up, levelling off near the strike width minus the debit. There is no upper breakeven - the trade is bullish. Only when the net debit is larger than the strike width does a second (upper) breakeven appear. A put diagonal mirrors this: it has an upper breakeven and stays profitable as the stock falls. The calculator shows _none_ for whichever breakeven does not exist. ## Worked example A fixed, hypothetical illustration - not live market data, and an estimate at one IV assumption. A stock trades at $100. You buy the 90-day $95 call for $9.00 and sell the 30-day $105 call for $2.00 - a call diagonal for a net debit of $7.00 per share, with 30% implied volatility assumed to hold. - Net debit / max loss: $7.00 × 100 = $700 per contract. - Far leg at the near expiry: the $95 call still has 60 days left, priced by Black-Scholes. - Estimated max profit: about $489, if the stock is right at the $105 short strike at the near expiration. - Lower breakeven: about $98.46; no upper breakeven - above the lower one this call diagonal stays profitable as the stock rises. - Return on debit: about 70% at the peak. Drop the IV assumption to 20% and the estimated profit shrinks; that sensitivity is the point - like a calendar, a diagonal is long vega and lives partly on what volatility does. Found this useful? Get the bi-weekly email Strategy breakdowns, the edge cases these calculators surface, and trades worth watching - free, no noise. Join the free email -> ## ⚠ Common mistakes - Treating the estimate as a guarantee. The far leg's value at the near expiry depends on IV; if IV falls, the real profit can be well below the figure shown. - Ignoring the direction. A diagonal is not market-neutral like a calendar - a call diagonal needs the stock to hold up, a put diagonal needs it to fall. Pick the type to match your view. - Setting the debit above the strike width. Pay more than the width apart and the upside (call) or downside (put) profit cap shrinks or disappears - check the return on debit before you open. - Forgetting early assignment. A short near leg that goes in-the-money can be assigned before its expiration, especially around ex-dividend dates. - Running it through earnings without a plan. The post-earnings volatility crush is exactly the move that hurts the long leg most. ## Frequently asked questions What is a diagonal spread? A diagonal spread sells a near-dated option and buys a longer-dated one at a different strike - both calls or both puts. It is a calendar spread with the strikes pulled apart, which adds a directional tilt: a call diagonal leans bullish, a put diagonal bearish. You pay a net debit because the longer leg costs more, and that debit is the most you can lose. Diagonal spread vs calendar spread - what is the difference? A calendar uses the same strike for both legs, so it is market-neutral and peaks at that strike. A diagonal uses two different strikes, so its peak shifts to the short strike and the trade takes on a direction. The calendar is a pure time-decay-and-volatility bet; the diagonal mixes that with a directional view. What is the maximum loss on a diagonal spread? The net debit you paid - the long premium minus the short premium, times 100 per contract - as long as it is built the standard way (a call diagonal with the long strike at or below the short, or a put diagonal with the long strike at or above it). In that configuration the debit caps the loss: it is a defined-risk trade. Why is the max profit only an estimate? Because at the near expiration the longer-dated leg you still hold has time left, so its value is not a fixed intrinsic number - it depends on implied volatility and days remaining. This calculator prices that far leg with Black-Scholes, assuming the IV you entered still holds. If IV shifts by then, the real result shifts too. Re-run it with higher and lower IV to test sensitivity. Diagonal spread vs a poor man's covered call - what is the difference? A poor man's covered call (PMCC) is one specific call diagonal: a deep in-the-money LEAPS call as a stock substitute with a short near-term call sold against it, run as ongoing income. This diagonal calculator is the general case - any two strikes and expirations, calls or puts - pricing the long leg with Black-Scholes rather than treating it as stock. When should I use a diagonal spread? When you want a calendar spread with a directional lean - you sell a near-dated option and buy a longer-dated one at a different strike, profiting from both time decay and a drift in your favour. It is the middle ground for a slow, mild trend. Skip it if your view is sharply directional and urgent (a long option or vertical is cleaner) or purely neutral (a plain calendar is simpler).