Which bolt is best?
Single-cylinder deadbolts use a key on one side, with a thumb-turn on the other.
Double-cylinder deadbolts require keys on both sides.
Double-cylinder deadbolts offer higher security but can be risky in emergencies.
Some municipalities have outlawed double-cylinder deadbolts.
When making decisions about the security of your home, deadbolts might not get the attention they deserve compared to other measures, like security systems. But while these systems can be a highly protective addition, a proper deadbolt can also protect you and your family.
Deadbolt locks are some of the first lines of defense for our homes, but if you’re shopping around for them, you might quickly realize not all deadbolt locks are equal. Our guide will walk you through the key differences between single- versus double-cylinder deadbolt locks so you can decide which may be better suited for certain parts of your home.
There are numerous mechanical differences between a single-cylinder versus a double-cylinder deadbolt lock, but it’s easy to tell them apart by sight. A single-cylinder deadbolt, the most common type of deadbolt found in homes, has a slot for a key on one of its sides, with the other side featuring a knob or turning mechanism. Often, this turning mechanism is a thumb-turn that looks like a simple lever and turns as a key would. Usually, this thumb-turn faces indoors, so it can lock the door the deadbolt is attached to without the need for keys.
The double-cylinder deadbolt requires a key on both sides. Whether you are indoors or outdoors, you would need a key to open or close the deadbolt.
| Type of Difference | Single-Cylinder | Double-Cylinder |
|---|---|---|
| Operation | Thumb-turn and key slot | Two key slots |
| Cost | Less expensive | More expensive |
| Ease of Use | Easier | More difficult |
| Ideal for | Universal usage | Entryways and back doors |
| Building Code Restrictions | Rarely | Possibly |
A single-cylinder deadbolt is the most common deadbolt you’ll find, and likely one you already have in your home. It features one side that opens the deadbolt using a key, and another side that opens the deadbolt using a knob (such as a thumb-turn) or other turning mechanism. The thumb-turn side usually faces the interior of the home for easy opening and closing.
| Pros | Cons |
|---|---|
| Cost-effective | Less secure than double-cylinder |
| Easy to unlock and lock | Safety risk with children |
Best for:
Those who want a simple, cost-effective solution
Families without small, adventure-seeking kids
Homeowners who live in low-crime areas
Changing a door lock can be difficult to DIY and damage the door's structure if not done correctly. For the best results, we recommend contacting a local pro.
Because of the thumb-turn, a single-cylinder deadbolt may be more straightforward for some family members to use versus a double-cylinder requiring a key turn for both sides. In addition, because the single-cylinder deadbolt depends on a thumb-turn on one side and a key on another, it’s much more cost-effective than the double-cylinder configuration.
Single-cylinder deadbolts offer additional security, but not as much as the double-cylinder because of its easier use with the thumb-turn. Because of this, a homeowner will need to think strategically about where to place a single-cylinder deadbolt. It’s best to avoid placing it near a window since a would-be burglar can break a window and quickly turn the lock. Single-cylinder deadbolts work best where you need more convenient access and away from windows, such as with a bedroom or bathroom door.
Their ease of use can be a liability as well. Because kids can figure out how to easily turn the knob to open the door, they could get outside at times when they shouldn’t be.
Double-cylinder deadbolt locks have key slots on both sides, so you use a key whether you’re accessing from the exterior or interior of the home. You must have a key for unlocking the double-cylinder on the door's interior and exterior sides.
Because double-cylinder locks are not a safe option for emergency exits, they’re not allowed in some jurisdictions, including within a city, state, or local building code enforcement. If you’re unsure of the fire codes where you live, check with your local regulations before installing a double-cylinder lock throughout your home or rental property, or contact a local locksmith near you for guidance.
| Pros | Cons |
|---|---|
| Enhanced security | Liability in emergency situations; illegal in some places |
| More expensive |
Best for:
Homeowners who want enhanced security
Homeowners who live in high-crime neighborhoods
Homeowners with glass-paneled doors
The main benefit of double-cylinder deadbolt locks is their enhanced security. Because they require a key on both sides, it is more difficult for an intruder to bypass them and gain entry to your home. If you have any doors with glass panels or adjacent to windows, a double-cylinder deadbolt could give you peace of mind.
If you have small children or cognitively-impaired adults in your home, a double-cylinder lock can prevent them from getting outside unsupervised.
Because the single-cylinder deadbolt depends on a thumb-turn on one side and a key on another, it’s much more cost-effective than the double-cylinder configuration. The cost of single-cylinder deadbolt locks is $20 to $70, compared to double-cylinder locks, which can sometimes cost over $100 (though there are less expensive models). When you need multiple locks around your home, price is an important factor.
In addition, a double-cylinder might be a liability in an emergency situation, such as a fire: When you’re trying to get out of your home quickly, you don’t want to be fumbling around looking for a key. In fact, that’s why these locks are illegal in some cities and states—so be sure to check your local laws before installing any in your home.
While a double-cylinder deadbolt might be excellent in specific scenarios—such as near glass doors, which can be easily broken by intruders—it’s important to weigh specific factors such as price and installation process before deciding on the best deadbolt for your home.
Because a double-cylinder deadbolt requires two keys, it is much more difficult for a burglar to open to gain access to your home.
When thinking of safety as your ability to quickly leave your home in an emergency such as a fire, a single-cylinder deadbolt is the way to go. Double-cylinder deadbolts are outlawed in some places because they can be a risk in an emergency situation.
While there are some double-cylinder deadbolts under $100, most are more expensive than single-cylinder options. Single-cylinder deadbolts can be purchased for as little as $20, which can offer significant savings if you have many doors to outfit with locks.
It is much easier to install a single-cylinder deadbolt, as double-cylinder models require drilling extra holes and aligning the locking mechanism to pair with the key on both sides of the door.
Because a single-cylinder deadbolt only requires a key on one side, many find it easier to use. With the requirement for a key to get both in and out of a door with a double-cylinder deadbolt, some homeowners might become quickly frustrated if they misplace their key and get locked inside.
You might assume that having two locks on one door will offer more protection than only one lock, but there may not be an advantage. While there’s nothing wrong with having two locks if you feel it’s best for your living situation, rest assured having one high-quality deadbolt installed correctly will offer a high level of protection.
A keypad deadbolt, a lock requiring a code entered on a keypad entry, can be a convenient option for families with children coming in and out and needing access to the home. It can also offer an easy solution if you rent your home out, since you can easily change the code as needed. So, depending on your home entry’s needs, a keypad deadbolt may be worth the extra expense.
