Choosing Expiration

You have picked your strategy and your strikes. Now: how long? The expiration date you choose affects everything — your cost, your time decay profile, your probability of profit, and how you manage the trade.

The Theta Curve

Time decay is not constant. It accelerates as expiration approaches. An option with 60 days left might lose $0.05 per day. At 30 days, it loses $0.08. At 10 days, $0.15. At 3 days, $0.30.

This curve is critical for choosing expirations:

If you are a buyer (debit spreads): You want slower decay. Go further out in time (45 to 60 DTE). This gives the stock time to move while minimizing the daily decay drag.
If you are a seller (credit spreads): You want to be in the steep part of the curve. Sell options with 30 to 45 DTE. The decay is accelerating in your favor.

DTE Guidelines by Strategy

Debit spreads (bull call, bear put):

Ideal: 45 to 60 DTE
Minimum: 30 DTE
Why: You need time for the stock to move. Too short and you are fighting theta.

Credit spreads (bull put, bear call):

Ideal: 30 to 45 DTE
Works: 21 to 50 DTE
Why: You want theta working aggressively but still have time to manage the trade if things go wrong.

Iron condors and iron butterflies:

Ideal: 30 to 45 DTE
Why: Same as credit spreads. You are selling premium and want time decay on your side.

Calendar spreads:

Front month: 20 to 30 DTE
Back month: 50 to 70 DTE
Why: Maximize the decay differential between the two legs.

Straddles and strangles (long):

Ideal: 30 to 60 DTE (unless playing a specific event)
Why: Need time for the stock to make a big move without daily theta eating you alive.

Matching Expiration to Your Catalyst

If you have a specific reason for the trade, match the expiration to it.

Earnings play (MSFT reports in 18 days):

Debit spread: Choose the expiration just after earnings (about 20 DTE). You want the option to still be alive when the catalyst hits.
Credit spread: Choose the expiration just before earnings (if you want to avoid the event) or after earnings (if you want the IV crush).

Technical breakout (stock approaching a trend line that should resolve in 1-2 weeks):

Give yourself 2x the expected time. If you think it breaks out in 10 days, use a 30-day expiration. This gives you a margin of error.

No specific catalyst (just a directional view):

Default to 45 DTE for debit spreads and 30 to 45 DTE for credit spreads. These are the statistical sweet spots based on theta behavior.

The Cost of Time

More time costs more money. An AAPL $190 call might be:

14 DTE: $3.00
30 DTE: $5.50
60 DTE: $8.00
90 DTE: $10.00

Notice the relationship is not linear. Going from 14 to 30 days costs $2.50 more (16 extra days). Going from 60 to 90 days costs $2.00 more (30 extra days). You pay less per additional day as you go further out.

This is why the 45 to 60 DTE window is efficient for buyers — you get a meaningful amount of time without overpaying.

Weeklies vs. Monthlies

Weekly options expire every Friday (or even daily for some ETFs). Monthly options expire the third Friday of each month.

Weeklies:

Higher theta per day (more decay)
Less time for the trade to work
Higher gamma (bigger daily swings)
Wider bid-ask spreads (less liquid)
Best for: Quick trades, selling premium very close to expiration

Monthlies:

More liquid (tighter bid-ask spreads)
Better Greeks behavior
More time for management
Best for: Most trades, especially spreads

If you are unsure, use monthlies. The liquidity advantage alone is worth it. Wider bid-ask spreads on weeklies can cost you $20 to $50 per trade in slippage.

The "Too Short" Trap

Newer traders gravitate toward shorter expirations because they are cheaper. A 7-day SPY put spread costs $0.50 instead of $1.50 for a 30-day spread. It feels like a better deal.

But the 7-day spread needs everything to go right immediately. One bad day can blow through your strikes. The 30-day spread gives you time to ride out volatility and manage the position.

Cheap expirations are often expensive in terms of probability. You save money upfront but you lose more often.

Practical Decision Framework

What is my catalyst or timeframe? Pick an expiration that gives you 1.5x to 2x that expected time.
Am I buying or selling? Buyers go longer (45-60 DTE). Sellers go shorter (30-45 DTE).
Is liquidity acceptable? Check open interest at that expiration. If it is thin, move to the nearest monthly.
Does the cost make sense? If the extra time costs 50% more but only gives you 10 more days, it may not be worth it. Find the efficient point.

Expiration selection is not glamorous but it is foundational. Get it wrong and even good strike selection cannot save you. Next up: what to do when your trade is winning.