What You're Actually Replacing

A lock cylinder is the part of your lock that you put your key into—the metal tube that rotates when you turn the key. It is not the whole lock. When a cylinder fails, you do not need to replace the entire lock body; you only swap out that one part, which takes about 15 minutes and costs $10 to $30 for the cylinder itself.

The cylinder sits inside a larger metal housing called the lock body. When you turn your key, the cylinder rotates inside that housing and triggers the bolt. If your key sticks, won't turn, or breaks inside the lock, the cylinder is what needs replacing. The rest of the lock mechanism usually stays in place.

Before you start, check whether your lock is keyed alike (all your doors use the same key) or keyed different (each door has its own key). You will need a replacement cylinder that matches your current key, or you will need to rekey it to match your existing key. Most hardware stores can rekey a cylinder while you wait for a small fee, usually $3 to $5.

Key Takeaways

  • A lock cylinder is the metal tube you insert your key into, and replacing it does not require removing the entire lock from the door.
  • You will need a screwdriver (usually Phillips head), your current key, and a replacement cylinder that matches your lock brand and keyway.
  • The cylinder is held in by a small screw on the inside edge of the door; removing that screw lets you pull the cylinder straight out.
  • After inserting the new cylinder, turn your key to the horizontal position before tightening the retaining screw, or the cylinder will jam.
  • If your new cylinder does not match your current key, take it to a locksmith or hardware store to have it rekeyed before installation.

Gather Your Tools and Replacement Cylinder

You need very little to replace a lock cylinder. Collect a Phillips head screwdriver (or flathead, depending on your lock), your current key, and the replacement cylinder itself. The replacement must match your lock's keyway—the shape of the hole where your key goes. Common keyways include Kwikset, Schlage, Weiser, and Baldwin. If you buy the wrong keyway, the key will not fit.

To find the right keyway, look at your current key or the lock itself. Many locks have the brand stamped on the face. If you are unsure, bring your key to the hardware store and ask the staff to match it. They can also tell you whether the cylinder is standard (1 inch long) or a non-standard length, which matters for some doors.

If you want the new cylinder to work with your existing key, ask the hardware store whether they rekey cylinders. Most do, and it takes 10 to 15 minutes. You will pay a small fee, but you avoid the hassle of rekeying it yourself. If you prefer to rekey it at home, you will need a rekey kit (usually $5 to $15), which comes with a special tool and springs.

Remove the Old Cylinder

Start with the door open so you can see and reach the inside of the lock. On the inside edge of the door (the edge that faces the frame when the door is closed), you will see a small screw. This is the retaining screw, and it holds the cylinder in place. Turn this screw counterclockwise with your screwdriver until it comes out completely. Do not lose it—you will use it again.

Once the screw is out, insert your key into the cylinder from the outside of the door. Turn the key to the horizontal position (pointing left or right, not up or down). This rotates the cylinder's internal plug so that the retaining pin inside the lock body clears the way. While the key is turned, gently pull the cylinder straight out toward you. It should slide out smoothly.

If the cylinder does not slide out, the key may not be turned far enough. Try rotating it a bit more, or wiggle the cylinder gently while pulling. Do not force it—forcing can break the cylinder or damage the lock body. Once it is out, set it aside and remove the key.

Insert the New Cylinder

Before you push the new cylinder in, insert your key into it and turn it to the horizontal position. This aligns the internal plug the same way it was aligned when you removed the old one. While the key is turned, slide the new cylinder straight into the lock body from the outside of the door. Push it in until it stops—you should feel it seat fully.

The cylinder should go in smoothly and sit flush with the lock body. If it does not, the keyway may be wrong, or the cylinder may be a different length than your original. Stop and check the keyway against your key before you proceed. Forcing a mismatched cylinder can jam the lock.

Once the cylinder is fully seated, keep the key turned to the horizontal position and insert the retaining screw through the hole on the inside of the lock. Tighten it clockwise with your screwdriver until it is snug. Do not overtighten—you only need enough pressure to hold the cylinder in place. Overtightening can crack the cylinder or strip the screw hole.

Test the Lock Before You Finish

With the retaining screw in place, turn your key back to the vertical position (up or down) and remove it. Now test the lock from both sides. From the outside, insert your key and turn it to lock and unlock the door. The bolt should move smoothly. From the inside, use the thumb turn (the knob or lever on the inside of the lock) to lock and unlock as well.

Open and close the door a few times to make sure the bolt retracts fully when you unlock it and extends fully when you lock it. If the bolt sticks or does not move all the way, the cylinder may not be seated correctly. Remove the retaining screw, pull the cylinder out, and reinstall it, making sure it goes in straight and all the way.

If the key turns but the bolt does not move, the cylinder may be the wrong keyway or the lock body itself may be damaged. In that case, you will need to replace the entire lock, not just the cylinder. If everything works smoothly, you are done.

What to Do If the New Cylinder Does Not Match Your Key

If you bought a new cylinder and it does not work with your current key, you have two options: rekey it yourself or take it to a locksmith or hardware store.

To rekey it yourself, you will need a rekey kit for your lock brand. The kit includes a special tool (called a plug follower or rekey tool) and a set of springs and pins. The process involves removing the cylinder again, using the tool to hold the springs in place while you swap out the pins inside the cylinder, and then reinstalling it. This is fiddly and takes practice. If you make a mistake, the lock will not work. Most people find it easier to pay a locksmith or hardware store $3 to $5 to do it.

To have it rekeyed by a professional, bring the cylinder and your current key to the store or locksmith. They will use a rekey machine to match the pins inside the cylinder to your key. You will have it back in 10 to 15 minutes, and then you can install it in your door following the steps above.

Common Mistakes to Avoid

The most common mistake is forgetting to turn the key to the horizontal position before pulling out the old cylinder or pushing in the new one. If you do not turn the key, the retaining pin inside the lock body will catch the cylinder and prevent it from moving. You will think the cylinder is stuck when really you just need to turn the key.

Another mistake is buying a cylinder with the wrong keyway. Always check the brand and keyway of your current lock before you buy a replacement. If you are not sure, bring your key or your old cylinder to the store and ask the staff to match it.

A third mistake is overtightening the retaining screw. You only need it tight enough to hold the cylinder in place. If you crank it down hard, you can crack the cylinder or strip the hole, and then you will have to replace the whole lock.

Finally, do not assume that a new cylinder will work with your old key. Many replacement cylinders come with different pins inside, so they require a different key. If you want to use your current key, ask the store to rekey the cylinder before you leave, or plan to rekey it yourself at home.

Frequently Asked Questions

Can I replace a lock cylinder without removing the door?

Yes. The cylinder comes out from the outside of the door while the door is still hanging on its hinges. You only need access to the inside edge of the door to remove and replace the retaining screw. You do not need to take the door off.

What if the key is stuck in the cylinder and I cannot turn it?

Try spraying a small amount of graphite powder or silicone-based lock lubricant into the keyway. Do not use WD-40 or oil-based lubricants—they attract dirt and make the problem worse. Let the lubricant sit for a minute, then try turning the key gently. If it still will not turn, the cylinder is damaged and needs replacing, which is what you are doing anyway.

Do I need to rekey the new cylinder to match my old key?

Only if you want to use your current key. If you are okay with a new key, you can install the cylinder as-is. If you want the new cylinder to work with your existing key, take it to a hardware store or locksmith to be rekeyed before you install it.

What if the new cylinder is a different length than the old one?

Most residential lock cylinders are the same standard length, but some doors have non-standard locks. If the new cylinder is too long or too short, it will not fit properly in the lock body. Measure your old cylinder before you buy a replacement, or bring the old cylinder to the store to match it.

Can I replace a cylinder in a deadbolt lock the same way?

Yes. Deadbolts work the same way—the cylinder sits inside the lock body and is held in by a retaining screw on the inside. Follow the same steps: turn the key to horizontal, remove the screw, pull out the old cylinder, and slide in the new one while the key is still turned.