Single vs Double Cylinder Deadbolt: This Guide Will Help You Decide

Key Takeaway

  • Single cylinder deadbolt employs a key on the outside and a thumb-turn on the inside to operate the lock. They provide reasonable level of security and great ease of use.
  • Double cylinder deadbolt requires a key on either side of the door to be operated. Though they are more secure but can cause safety concerns during emergencies.

When it comes to securing front doors, deadbolts should definitely be your first choice. But choosing the best deadbolt is not an easy task especially making the decision between a single cylinder and double cylinder deadbolt.

In this article, we will compare single vs double cylinder deadbolts that will help you make the right decision.

We will look at factors like security, convenience and cost. We will also list down possible scenarios in which each one of them should be preferred.

So let’s get started.  

Main Difference Between Single Cylinder & Double Cylinder Deadbolt

The only difference between a single cylinder and double cylinder deadbolt is how the bolt gets activated on the inside of the door.

  • In a single cylinder deadbolt, the bolt is activated with a key on the outside and a thumb-turn on the inside.
  • Whereas in a double cylinder deadbolt, the bolt is activated with a key on either side of the door.

This difference may seem small, however it impacts the cost, security and the convenience aspects. Let’s take a look at them in detail now.

Pros And Cons Of Single And Double Cylinder Deadbolts

Here are the advantages and disadvantages of single and double cylinder deadbolts to consider.

Single Cylinder DeadboltsDouble Cylinder Deadbolts
SecuritySince thumb-turn is required to operate the bolt, they are less secure if installed near a glass windowProvides better security as the lock can only be opened using the key from both inside and outside.
Egress During EmergenciesFleeing in cases of emergency like fire or other calamities is easier for the ones inside the home.Escaping in emergency situations is more difficult.
CostCheaper than double sided deadboltsMore expensive
Ease Of InstallationEasy to install, hence the cost of installation is lowerMore complex to install, hence the cost of installation is higher
Time SavingSaves time while locking the home from inside.Locking the home from the inside takes as much time as it takes while locking from the outside, as both require a key.
Best Suited ForResidential Purposes
However add a dead latch along with deadbolt
Not recommended for high footfall areas like homes


Even though the working principle of both types of deadbolts is the same, double cylinder deadbolts are considered to be more secure.

I am sure it is not that difficult to see the reason why. Anyone who can get access to the thumb-turn (on single cylinder deadbolt) by either breaking the glass nearby or some other method, can unlock the door.

Since a double cylinder deadbolt requires a key on the inside as well (to open the door), you don’t have to worry about this concern.

Pro-Tip: Always ensure that there is more than a arm’s length distance between a nearby glass window and the thumb-turn. Recommended gap is 50 inches at-least.

Egress During Emergencies

Single cylinder deadbolts provide easy and fast egress during emergencies than a double cylinder deadbolt.

Since a double cylinder deadbolt requires a key (on the inside) to open the lock, it can create un-necessary delay during emergencies (like fire, earthquakes etc) leading to potential loss of lives. That’s why it is recommended to use a single cylinder deadbolt in homes.

Recommendation: If you have children or elder people at home, it is always advised to install a single cylinder deadbolt because of this reason only.


Single Cylinder deadbolts are comparatively cheaper than double cylinder deadbolts, which is perhaps another reason why majority of American homes install these. 

Besides the higher product cost, installation of double cylinder deadbolts is also more expensive as compared to their counterparts.


The ability to use a thumb-turn to lock or unlock the door from the interior of the home provides a measure of convenience that the modern homeowner has become accustomed to. Hence, there is no second thought that single-cylinder deadbolt locks definitely score more on the convenience part as compared to the double-cylinder deadbolt.

Which One Is Better – Single vs Double Cylinder Deadbolt?

Single cylinder deadbolt is definitely a better choice when it comes to protecting our homes where we want reasonable security and ample convenience. This becomes even more important when we have kids or elders at home since we would want faster egress during emergencies.

Double cylinder deadbolts make more sense where footfall is not that high and the area needs extra security like a research lab.

What About Double Cylinder Deadbolt Legalities?

In general, installing a double cylinder deadbolt is legal and you shouldn’t face any problems. But since they can be emergency hazard, some municipal corporations might restrict their usage.

If you live in an apartment, you might first want to check the building codes and ensure that double cylinder deadbolts or a single cylinder deadbolt without a thumb-turn is permissible. For example in California, they are permissible only in Group-B occupancies.

Frequently Asked Questions

Q1. Is it recommended to use double cylinder deadbolt in an apartment?

Answer – It is not recommended to use a double cylinder deadbolt in an apartment because of safety concerns. In case of emergencies like a fire, the occupants will be trapped inside if they don’t have the key handy.


As a homeowner, if you have decided to install a deadbolt on your door to secure your place, deciding between a single-cylinder deadbolt and a double-cylinder deadbolt can become difficult. 

The choice ultimately comes down to deciding between security and convenience. If security is your main concern, go for double cylinder deadbolt. However if you are fine with reasonable level of security with ample convenience, then single cylinder deadbolt makes for a better choice.  

Do let me know if you have any questions and I will be glad to answer them.

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Hey! I am Mark. Though I am not a locksmith by profession, but locks have always fascinated me since my teens. And it all started when I got locked out of my house and I had to pick the lock. Since then it has become my hobby to learn more about different kinds of locks, understand their working and methods to pick them up. In due course of time, I have also become better aware of how installing the right lock goes a long way in ensuring iron clad security. I aim to share my passion (about locks) through this blog. If you are also passionate about picking locks or are just looking to beef up the security, hop on the ride.