How to use this calculator
- Enter the current share price and days to expiration.
- Enter the long call you buy - its strike and the premium paid.
- Enter the short call you sell - its strike and the premium received.
- Set the number of contracts - the calculator detects a bull call (debit) or bear call (credit) spread from the strike order.
- Read the result: net debit or credit, max profit, max loss, breakeven, and return on risk.
What it tells you: the capped profit, loss, and breakeven of a vertical call spread before you place it.
How this calculator works
A call spread has two legs in the same expiration: a call you buy and a call you sell at a different strike. Which strike you buy decides everything. Buy the lower strike and sell the higher one and you have a bull call (debit) spread — you pay a net debit and want the stock to rise. Sell the lower strike and buy the higher one and you have a bear call (credit) spread — you collect a net credit and want the stock to stay below your short strike.
Enter both strikes and both premiums and the calculator detects the type from the strike order, then returns the numbers that define the trade. Because the payoff is a straight line that bends only at the strikes, the most you can make and the most you can lose both sit at the ends — the calculator reads them off those corners, so the figures hold for either type.
Max profit and max loss are each capped by the long leg. Breakeven is the lower strike plus the net debit or credit per share. Return on risk is max profit ÷ capital at risk, with an annualized version that scales it by 365 ÷ days to expiration.
Bull call vs bear call
A bull call spread is a directional bet you pay for: the net debit is your max loss, and you profit as the stock climbs toward the higher strike, capped at the strike width minus the debit. It needs the move to actually happen, and time decay works against you.
A bear call spread is premium you sell: the net credit is your max profit, kept when the stock stays at or below the lower (short) strike, and your loss is capped at the width minus the credit. Time decay works for you, and you do not need the stock to move at all — only to stay below your strike.
Worked example
A fixed, hypothetical illustration — not live market data.
A hypothetical stock trades at $100. With 30 days to expiration you buy the $100 call for $5.00 and sell the $110 call for $2.00 — a bull call spread for a net debit of $3.00 per share.
- Net debit: $3.00 × 100 = $300 per contract (your max loss).
- Strike width: $110 − $100 = $10.
- Max profit: ($10 − $3) × 100 = $700, if the stock is at or above $110 at expiration.
- Breakeven: $100 + $3.00 = $103.
- Return on risk: $700 ÷ $300 ≈ 233% over 30 days.
Common mistakes
- Confusing the debit and credit versions. Buying the lower strike pays for an upward move; selling the lower strike collects premium for the stock staying put. They are opposite trades built from the same two calls.
- Paying too much for a debit spread. If the net debit approaches the strike width, the most you can make shrinks toward zero — you are paying nearly the full payoff up front.
- Forgetting time decay. A bull call spread loses value as expiration nears unless the stock moves; a bear call spread gains from that same decay.
- Ignoring early assignment. A short call that goes in-the-money — especially before an ex-dividend date — can be assigned early, leaving you short stock.
- Misreading the annualized return. A few-week spread can annualize to triple or quadruple digits; that is arithmetic, not an expected compounding rate.
Frequently asked questions
What is a call spread?
A call (vertical) spread is a two-leg options trade: you buy one call and sell another call at a different strike in the same expiration. Buying the lower strike and selling the higher one is a bull call (debit) spread — you pay to open it and profit if the stock rises. Selling the lower strike and buying the higher one is a bear call (credit) spread — you collect a credit and profit if the stock stays below your short strike. Either way the second leg caps both the cost and the risk.
What is the difference between a bull call and a bear call spread?
They are mirror images built from the same two calls. A bull call spread is a net debit: you buy the lower-strike call (which costs more) and sell the higher-strike one, betting the stock rises toward the higher strike. A bear call spread is a net credit: you sell the lower-strike call and buy the higher-strike one for protection, betting the stock stays below the strike you sold. The calculator detects which you have entered from the strike order.
How is max profit on a bull call (debit) spread calculated?
Max profit = (strike width − net debit) × 100 per contract, reached when the stock finishes at or above the higher (short) strike so both calls are in the money. Max loss is just the net debit you paid, reached when the stock finishes at or below the lower (long) strike and both calls expire worthless.
What is the breakeven on a call spread?
For both types the breakeven is the lower strike plus the net debit or credit per share. For a bull call spread that is the long strike plus the debit; for a bear call spread it is the short strike plus the credit. At that price the position is exactly flat at expiration.
Call spread vs put spread — which should I use?
They express the same view from opposite sides. A bull call spread (debit) and a bull put spread (credit) are both bullish with defined risk; the call version costs money up front and profits as the stock rises, the put version pays you up front and profits if the stock simply holds above your short strike. Credit spreads benefit from time decay working for you; debit spreads need the move to actually happen. Pick the credit spread to sell premium, the debit spread to pay for a directional move.
Why is the annualized return so high?
Annualized return scales the return on risk by 365 ÷ days to expiration, so a short-dated spread extrapolates a few weeks across a whole year and produces a very large percentage. Debit spreads, whose max profit can exceed the capital at risk, look especially large. Treat it as a way to compare trades of different lengths, not a return you should expect to compound.
When should I use a call spread?
When you have a directional view but want to cap both cost and risk. Buy a bull call (debit) spread when you expect a move up and want cheaper, defined-risk exposure than a long call; sell a bear call (credit) spread when you expect a stock to stay below a level and want to collect premium with a known max loss. Each trades away a slice of the payoff for a much smaller bill than the naked option. Skip a debit spread if you expect an explosive move, since the short strike caps your upside, and skip a credit spread in a strong uptrend, where you are selling against the trend for a small credit and a larger risk.
Related tools and guides
Prefer to sell put premium for the same bullish view? See the Bull Put Spread Calculator. Selling premium on both sides at once? Use the Iron Condor Calculator, or map any structure 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.
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.