Calendar Spread Calculator

Time & DiagonalneutralDefined Risk

Buy a longer-dated option and sell a shorter-dated option at the same strike to profit from time decay.

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What Is a Calendar Spread?

A calendar spread, also called a time spread or horizontal spread, sells a near-term option and buys a longer-dated option at the same strike on the same underlying. The most common version uses at-the-money calls, though puts work identically. Because the longer-dated option costs more, the position is opened for a net debit, and that debit is the maximum loss.

The trade profits from the difference in time decay between the two expirations. The short option loses value quickly as its expiration approaches while the long option, with more time remaining, loses value slowly. The calendar is also long vega: a rise in implied volatility lifts the long option more than the short one, so calendars are often used ahead of events where volatility is expected to rise.

At the front-month expiration the payoff curve is a tent centered on the shared strike. Profit peaks when the stock finishes exactly at the strike, because the short option expires worthless while the long option retains the most time value. The tent slopes down on both sides and the loss approaches the net debit as the stock moves far away, because the long option's remaining value collapses toward its intrinsic value.

Setup

SELL1x ATM CALL

BUY1x ATM CALL

Max Profit

Difference in time value decay

Max Loss

Net debit paid

Breakeven

Depends on IV and time decay

Calendar Spread Example

XYZ trades at $100. You sell the $100 call expiring in 30 days for $2.50 and buy the $100 call expiring in 90 days for $4.50. The net debit is $2.00 per share, or $200 per spread. At the front-month expiration the long call will have 60 days remaining.

Stock at expiration	Result
$100 (unchanged)	The short call expires worthless. The long call, at the money with 60 days left, is assumed to be worth $3.60. Position value is $360 against a $200 cost, a gain of $160, the approximate maximum.
$105	The short call is $5.00 in the money and costs $500 to close. The long call is assumed to be worth $7.40 ($5.00 intrinsic plus $2.40 time value). Net value is $740 minus $500, or $240, a gain of $40.
$95	The short call expires worthless. The long call, $5.00 out of the money with 60 days left, is assumed to be worth $1.70. Position value is $170, a loss of $30.
$115	The short call is $15.00 in the money and costs $1,500 to close. The long call is assumed to be worth $15.40 ($15.00 intrinsic plus only $0.40 time value). Net value is $1,540 minus $1,500, or $40, a loss of $160. Loss approaches the full $200 debit on larger moves.

Maximum profit is roughly $160 if XYZ pins the $100 strike at the front-month expiration, with the exact figure depending on the long call's implied volatility at that time. Maximum loss is the $200 net debit. Approximate breakevens are near $96 and $106, giving a profit zone of about $10 wide.

When to Use a Calendar Spread

You expect the stock to stay near the strike price through the front-month expiration.
Implied volatility is low relative to its history and you expect it to rise, since the position gains from higher volatility in the back month.
The front-month implied volatility is higher than the back-month volatility, which makes the short option relatively expensive and lowers the net debit.
An earnings report or other event falls after the front expiration but before the back expiration, so the back-month option holds an event premium the front month does not.
Typical entries sell 30 to 45 days to expiration and buy 60 to 120 days, at the strike closest to the current stock price or to a price target.

Risks to Understand

A large move in either direction pushes both options deep in or out of the money, collapsing the time value differential and producing a loss close to the full debit.
A drop in implied volatility hurts the long option more than the short option and can produce a loss even if the stock stays exactly at the strike.
If the short option finishes in the money and is assigned, you take on a stock position over the weekend that the long option only partially hedges in the near term.
The back-month option is often less liquid than the front month, so the bid-ask spread on the long leg can be a meaningful fraction of the expected profit.
The profit zone is narrow. In the example the trade needs the stock to finish within about $5 of the strike to make money.

Managing the Trade

Close the spread on or before the front-month expiration day. Holding a short option into expiration near the strike creates pin risk and unwanted assignment.
If the stock drifts away from the strike, roll the short option to the new at-the-money strike in the same expiration, converting the calendar into a diagonal.
If the front option decays to a small fraction of its value early, buy it back and sell the next month, keeping the long option and collecting another round of premium.
Take profit at 25 to 50 percent of the debit paid. Calendars rarely reach their theoretical maximum because the stock seldom pins the strike precisely.
Set a loss limit at around half the debit. A calendar losing that much usually means the stock has moved well away from the strike or volatility has fallen, and the thesis is broken.

Calendar Spread FAQs

How does a calendar spread make money?: It profits when the near-term option loses value faster than the longer-dated option, which happens when the stock stays close to the strike. It also gains when implied volatility rises, because the longer-dated option has more sensitivity to volatility than the short one.
What is the max loss on a calendar spread?: The net debit paid to open the position. Because the long option expires after the short option and shares the same strike, it always covers the short option, so the loss cannot exceed the debit at the front-month expiration.
How do you calculate calendar spread max profit?: There is no closed-form answer because it depends on what the long option is worth when the short option expires. Estimate it by pricing the long option at the strike with its remaining days and current implied volatility, then subtract the net debit. In the example the long call is worth about $3.60, so max profit is about $160.
Is a calendar spread bullish or bearish?: A calendar at the current stock price is neutral. Placing the strike above the stock makes it mildly bullish, since the stock needs to rise toward the strike for maximum profit, and placing it below makes it mildly bearish. Put and call calendars at the same strike have nearly identical payoffs.
Should I use puts or calls for a calendar spread?: For a neutral at-the-money calendar it makes little difference because put-call parity keeps the payoffs close. Many traders use out-of-the-money options for the chosen strike to reduce early assignment risk: puts for strikes below the stock and calls for strikes above.
What happens to a calendar spread when volatility drops?: The position loses value. The long option has more vega than the short option, so a volatility decline reduces its price by more than it reduces the short option's price. This is why calendars are best entered when implied volatility is low rather than after a spike.

Related Strategies

Poor Man's Covered Call (PMCC)Iron Condor

What Is a Calendar Spread?

Calendar Spread Example

Stock at expiration	Result
$100 (unchanged)	The short call expires worthless. The long call, at the money with 60 days left, is assumed to be worth $3.60. Position value is $360 against a $200 cost, a gain of $160, the approximate maximum.
$105	The short call is $5.00 in the money and costs $500 to close. The long call is assumed to be worth $7.40 ($5.00 intrinsic plus $2.40 time value). Net value is $740 minus $500, or $240, a gain of $40.
$95	The short call expires worthless. The long call, $5.00 out of the money with 60 days left, is assumed to be worth $1.70. Position value is $170, a loss of $30.
$115	The short call is $15.00 in the money and costs $1,500 to close. The long call is assumed to be worth $15.40 ($15.00 intrinsic plus only $0.40 time value). Net value is $1,540 minus $1,500, or $40, a loss of $160. Loss approaches the full $200 debit on larger moves.

When to Use a Calendar Spread

You expect the stock to stay near the strike price through the front-month expiration.

Implied volatility is low relative to its history and you expect it to rise, since the position gains from higher volatility in the back month.

The front-month implied volatility is higher than the back-month volatility, which makes the short option relatively expensive and lowers the net debit.

An earnings report or other event falls after the front expiration but before the back expiration, so the back-month option holds an event premium the front month does not.

Typical entries sell 30 to 45 days to expiration and buy 60 to 120 days, at the strike closest to the current stock price or to a price target.

Risks to Understand

A large move in either direction pushes both options deep in or out of the money, collapsing the time value differential and producing a loss close to the full debit.

A drop in implied volatility hurts the long option more than the short option and can produce a loss even if the stock stays exactly at the strike.

If the short option finishes in the money and is assigned, you take on a stock position over the weekend that the long option only partially hedges in the near term.

The back-month option is often less liquid than the front month, so the bid-ask spread on the long leg can be a meaningful fraction of the expected profit.

The profit zone is narrow. In the example the trade needs the stock to finish within about $5 of the strike to make money.

Managing the Trade

Close the spread on or before the front-month expiration day. Holding a short option into expiration near the strike creates pin risk and unwanted assignment.

If the stock drifts away from the strike, roll the short option to the new at-the-money strike in the same expiration, converting the calendar into a diagonal.

If the front option decays to a small fraction of its value early, buy it back and sell the next month, keeping the long option and collecting another round of premium.

Take profit at 25 to 50 percent of the debit paid. Calendars rarely reach their theoretical maximum because the stock seldom pins the strike precisely.

Set a loss limit at around half the debit. A calendar losing that much usually means the stock has moved well away from the strike or volatility has fallen, and the thesis is broken.

Calendar Spread FAQs

How does a calendar spread make money?

It profits when the near-term option loses value faster than the longer-dated option, which happens when the stock stays close to the strike. It also gains when implied volatility rises, because the longer-dated option has more sensitivity to volatility than the short one.

What is the max loss on a calendar spread?

The net debit paid to open the position. Because the long option expires after the short option and shares the same strike, it always covers the short option, so the loss cannot exceed the debit at the front-month expiration.

How do you calculate calendar spread max profit?

There is no closed-form answer because it depends on what the long option is worth when the short option expires. Estimate it by pricing the long option at the strike with its remaining days and current implied volatility, then subtract the net debit. In the example the long call is worth about $3.60, so max profit is about $160.

Is a calendar spread bullish or bearish?

A calendar at the current stock price is neutral. Placing the strike above the stock makes it mildly bullish, since the stock needs to rise toward the strike for maximum profit, and placing it below makes it mildly bearish. Put and call calendars at the same strike have nearly identical payoffs.

Should I use puts or calls for a calendar spread?

For a neutral at-the-money calendar it makes little difference because put-call parity keeps the payoffs close. Many traders use out-of-the-money options for the chosen strike to reduce early assignment risk: puts for strikes below the stock and calls for strikes above.

What happens to a calendar spread when volatility drops?

The position loses value. The long option has more vega than the short option, so a volatility decline reduces its price by more than it reduces the short option's price. This is why calendars are best entered when implied volatility is low rather than after a spike.