Calendar Spread Calculator
Calculate the net debit and maximum loss for a calendar spread (time spread) strategy. Enter the strike price and premiums for both expirations to understand your cost basis and downside risk.
Enter the shared strike price and the premium for each expiration to calculate your calendar spread cost.
Enter your calendar spread strike and premiums, then click Calculate Calendar Spread to see net debit, max loss, and strategy insights.
For educational purposes only. Not financial advice. Read full disclaimer
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Calendar Spread Formulas
Net Debit = (Far Premium - Near Premium) x 100 x Contracts
Max Loss = Net Debit (total cost of the spread)
Max Profit = Variable (depends on IV and time decay at near expiration)
Breakeven = Variable (depends on IV at near-term expiration)
Worked Examples
Example 1: AAPL Calendar Spread
AAPL is trading at $200. You sell the 30-day $200 call for $3.00 and buy the 60-day $200 call for $5.50. 1 contract.
- Net Debit = ($5.50 - $3.00) x 100 = $250
- Max Loss = $250 (if both expire worthless or deep ITM)
- Max Profit = Variable — depends on IV and underlying price at 30-day expiration
- Best case: AAPL expires near $200 at near-term expiration, and IV stays elevated for the far-term option
Example 2: SPY Calendar Spread with 10 Contracts
SPY is trading at $450. You sell the weekly $450 call for $2.50 and buy the monthly $450 call for $6.00. 10 contracts.
- Net Debit = ($6.00 - $2.50) x 100 x 10 = $3,500
- Max Loss = $3,500 (total debit paid)
- Max Profit = Variable — highest when SPY is at $450 at weekly expiration
- The near-term option decays faster, widening the spread value in your favor
How to Use This Calculator
- Enter the strike price — both options share the same strike. This is typically at or near the current underlying price.
- Enter the near-term premium received — the credit you receive from selling the shorter-dated option.
- Enter the far-term premium paid — the cost of buying the longer-dated option. This must be more than the near-term premium.
- Set the number of contracts — each contract covers 100 shares. The calculator scales all dollar amounts accordingly.
- Click Calculate — review the net debit (your cost), maximum loss, and educational notes about why max profit is variable.
Frequently Asked Questions
- What is a calendar spread?
- A calendar spread (also called a time spread or horizontal spread) involves selling a near-term option and buying a longer-term option at the same strike price. The strategy profits from the difference in time decay rates between the two expirations. The near-term option loses value faster, generating profit as it decays toward zero.
- How does time decay benefit a calendar spread?
- Theta (time decay) accelerates as expiration approaches. The near-term option you sold decays faster than the far-term option you bought. This difference in decay rates is the primary profit driver. As the near-term option loses value quickly, the spread widens in your favor — assuming the underlying stays near the strike price.
- How does implied volatility affect a calendar spread?
- Calendar spreads are long vega — they benefit from rising implied volatility. Since the far-term option has more vega exposure than the near-term option, an increase in IV raises the value of the far-term option more than the near-term option, widening the spread. Conversely, a drop in IV hurts the position.
- When should you use a calendar spread?
- Calendar spreads work best when you expect the underlying to stay near a specific price and you anticipate stable or rising implied volatility. Common setups include trading around a stock that has been range-bound, or positioning before an event where IV is expected to increase for the far-term expiration.
- Why can't this calculator show exact max profit or breakeven?
- Unlike vertical spreads or butterflies, calendar spreads involve options with different expirations. When the near-term option expires, the far-term option still has time value that depends on implied volatility, the underlying price, and remaining days to expiration. Calculating the exact max profit requires a full options pricing model like Black-Scholes at the point of near-term expiration.