How do you measure the cylinder size of your front door?
Get started with the cylinder size
A cylinder size consists of 2 parts, the inner size and outer size. In this article, we'll explain how to measure these sizes. To follow these 4 steps, you need a tape measure or ruler.
- Step 1: find the adjustment screw
- Step 2: measure the inner size
- Step 3: measure the outer size
- Step 4: check if you have a standard size
Step 1: find the adjustment screw
The cylinder is the part of your door you slide your key into. It runs from the outside of your door to the inside. Cylinders have various lengths, depending on the width of your door and to where the lock extends. That's why you have to measure 2 things. Measure the distance from the outside of your door to the center of the lock. Then, measure the distance from the center of the look to the inside of your door. Use the adjustment screw above the lock as a measuring point to find the center of the lock. It usually has a clear center.
Step 2: measure the inner dimension
The inner dimension runs from the adjustment screw to the end of the cylinder. Hold a piece of wood or book against the lock pointing inwards. Then, measure the distance from the book to the center of the adjustment screw on the side of the door. Write down the distance in millimeters. Keep in mind that the distance should be divisible by 5, such as 30 or 45.
Step 3: measure the outer dimension
Measure the outer dimension of the lock in the same way, but from the part of the lock that points outwards. Sometimes, the outer cylinder sticks out a little. You can than use the distance from the lock to the end of the plate that's been mounted on the door. Write down this number in millimeters before the inner dimension, so you get a number like 35-30. The first number should be the outer dimension, and the second number should be the inner dimension.
Step 4: check if you have a standard dimension
Do you have a 2-digit cylinder size between 30 and 70 and is it divisible by 5? You've measured the cylinder correctly. If you got a different number, measure again and check if you get a multiple of 5. To do this, loosen the adjustment screw from step 1 and take the cylinder out of your door. You should still measure it from the center of the adjustment screw.
