Choosing a Protective Put's Strike and Expiration
Reviewed by Leon Moyer - Published October 9, 2026 - Last reviewed October 9, 2026
In this lesson
Compare protective puts by premium, worst case and cost per month of cover, and choose a strike and expiration that match the risk you want to cap.
To choose a protective put, pick the strike from the most you can stand to lose and the expiration from how long the risk lasts. A higher strike is a higher floor and a higher premium; a longer expiration costs more in total but usually less for each month of cover. The right put is the one whose worst case and cost you can both accept.
This lesson compares real trade-offs on the position from Protective Puts in Depth: 100 shares of XYZ bought at $52. New model inputs for the rest of this module: XYZ at $52, 35% implied volatility, a 4.5% interest rate and, unless a table says otherwise, 45 days to expiration. Every premium below is a model price from the same pricing engine the free OptionsPro profit calculator uses, at those inputs. At these inputs the 45-day 50 put prices at $1.52, two cents more than the $1.50 quote used in the previous lesson. Real quotes will differ, especially for puts well below the stock price, which usually trade at higher implied volatility than this model assumes.
How does the strike change a protective put?
For any strike, the same three formulas apply, at expiration and before fees:
- Maximum loss = (stock price paid - strike + premium) x 100.
- Maximum profit is unlimited, less the premium.
- Break-even = stock price paid + premium.
So the strike moves two things in opposite directions. Raising it shrinks the deductible, the stretch the stock can fall before the put starts paying, but raises the premium, which also raises the break-even.
Four 45-day XYZ puts: what each costs and what it leaves at risk
Premium per contract
Worst case at expiration
Worked example
Four 45-day puts on 100 XYZ at $52
The cheapest put, the 45, costs only $32, but it lets the position lose $732 before the floor holds. The at-the-money 52 put has no deductible at all, but at $240 it costs more than seven times as much and needs XYZ above $54.40 to break even.
Notice that the worst case falls as the strike rises, even though the premium climbs. Each step up in strike removes more deductible than it adds in premium. What you pay for that is certain: the premium is gone even if XYZ never falls.
Illustrative and hypothetical. The ticker and prices are invented for teaching, and the figures exclude commissions, fees, margin interest and taxes, which reduce real results. Past or hypothetical outcomes do not indicate future results.
Cheap protection or close protection?
100 XYZ at $52 protected by a 45 put or a 50 put, at expiration
Hover or tap the chart, or focus it and use the arrow keys, to read any price.
Open this trade in the free calculatorShow as table
The chart puts the 45 put and the 50 put side by side. Above $50 the lines are close: the cheaper put trails the shares by $32, the closer one by $152. Below $50 they separate fast. The 50 put stops the loss at $352; the 45 put keeps losing until $45 and stops at $732.
This is the real choice. A far out-of-the-money put is disaster insurance: cheap, and useful only if something goes badly wrong. A near-the-money put is close protection: it starts working almost immediately, and you pay for that every time you buy it. Neither is better in general. The question is which loss you are actually trying to prevent.
A simple way to start is from your limit. If you can accept losing $400 on this position, the 50 put fits ($352). If you can accept $750, the 45 put fits, and saves $120.
How does the expiration change the cost?
Longer puts cost more, because they cover more time. But they do not cost proportionally more.
The XYZ 50 put at five expirations
Premium per contract
Average cost per 30 days of cover
Worked example
The XYZ 50 put at five expirations
Three months of cover costs about twice as much as one month, not three times as much. A full year costs less than five times as much as one month.
The per-30-day column is a simple average for comparing costs. It is not theta: a put's actual daily decay is uneven and depends on where the stock trades.
Illustrative and hypothetical. The ticker and prices are invented for teaching, and the figures exclude commissions, fees, margin interest and taxes, which reduce real results. Past or hypothetical outcomes do not indicate future results.
That pattern comes from how time value behaves. It grows roughly with the square root of the time left, so short-dated options lose value fastest, as What Is Theta in Options? Time Decay in Dollars per Day explains. A hedger who keeps buying one-month puts pays the steep part of that curve every month.
Longer is not automatically better, though:
- You pay more up front for cover you might not need for the whole period.
- If the stock rises a lot, a long put's floor ends up far below the market, protecting a price you have already left behind. You might then sell it and buy a new, higher put.
- If the risk is a single event, such as one earnings report, a put that expires shortly after it may be all you need. Expect it to cost more than the 30-day line above suggests, though, for the reason in the next section.
Why is protection cheapest before you need it?
When a stock falls, its puts get more expensive for two reasons. The put is closer to the money, and implied volatility usually rises as traders rush to buy protection. A hedge bought after a sell-off has started often costs much more than the same hedge bought a week earlier.
A scheduled event is different. Before an earnings date, puts that expire after it already carry extra implied volatility priced for the announcement, so they cost more than this lesson's flat 35% model shows. That implied volatility usually falls once the news is out, which lowers the put's value even if the stock does not move, as IV Crush After Earnings - Why Options Can Lose Value explains. Deciding in advance still beats deciding in a panic after a drop, but event protection is rarely cheap.
Check your understanding
You own 100 shares bought at $52 and buy the 47.5 put for $0.76. What is the worst case at expiration?
Show answer
$526. ($52 - $47.50 + $0.76) x 100: a $450 deductible plus the $76 premium.
Why can the worst case fall as you pay more for a higher strike?
Show answer
Each step up in strike removes more deductible than it adds in premium, so the floor rises faster than the cost.
The 90-day put costs $238 and the 30-day put $113. Which costs less per month of cover?
Show answer
The 90-day put: about $79 per 30 days, against $113 for the 30-day put.
Key takeaways
- Choose the strike from your loss limit: worst case = (stock price paid - strike + premium) x 100.
- Higher strikes cost more but leave less at risk; far out-of-the-money puts are cheap disaster insurance.
- Longer puts cost more in total but less per month, because time value grows more slowly than time.
- Protection is usually cheapest before a decline, when implied volatility is lower.
Common questions
What strike price should I use for a protective put?
Start from the most you are willing to lose. The worst case is (stock price - strike + premium) x 100, so work backward to the strike that keeps it within your limit, then check what that strike costs. Higher strikes protect more and cost more.
Is it better to buy a protective put in the money or out of the money?
Neither is better in general. An in-the-money or at-the-money put leaves almost no deductible but costs the most. An out-of-the-money put is cheaper but only protects after a larger drop. One common middle ground is a strike a few percent below the stock price.
How far out should a protective put expire?
Long enough to cover the risk you are worried about, with room to spare. Longer puts cost more in total but usually less per month of protection, so a single longer put often costs less than several short ones bought back to back.
Why do protective puts cost more after a stock drops?
Two reasons. The put is closer to the money, so it has more value, and implied volatility usually rises when a stock falls, which raises put prices further. Protection is generally cheapest to buy before it is needed.