How to Measure Your Cylinder

Are you considering upgrading your door with our Tapkey Smart Lock, but unsure how to measure your cylinder to ensure a proper fit? Fear not, measuring your cylinder is a straightforward process that can be completed in just a few simple steps. Follow these instructions to ensure a successful installation:

Step 1: Prepare Your Door

Before starting, make sure your key is on the outside of the door.

Step 2: Remove the Cylinder

Remove the screw on the lock face and slightly rotate your key. Then, gently pull out the cylinder to remove it from the lock.

Step 3: Measure Your Cylinder

Using a tape measure or ruler, measure the cylinder's length from the outside (where the key is) until the hole in the middle—make sure you measure until the middle of the hole and not just its start. Then, measure the cylinder from the inside (where the key isn't) the same way. Take note of both measurements.

Step 4: Select Your Smart Lock

With your measurements in hand, you can confidently choose the Tapkey Smart Lock measurements that fit your cylinder's dimensions. Be sure to double-check the product specifications before making a purchase.

Step 5: Install Your Smart Lock

Now that you have your smart lock, it's time to install it. Be sure to carefully follow the instructions to ensure a safe and successful installation. Follow either: 

How you'll know if your door has core pulling protection? To check, you can inspect the lock mechanism itself. If the lock has a steel plate surrounding the core, then it likely has core pulling protection.


By following these simple steps, you can easily measure your cylinder and retrofit a Tapkey Smart Lock on your door. Don't forget, if you have any questions or concerns, our customer support team is here to help.