How to remove and measure a locking cylinder

Would you like to purchase a new locking cylinder and install it in your door, but don't know the length of cylinder you need to order? We explain it to you here.

There are two ways to determine the length of a cylinder.

Option 1

Determine the cylinder length by measuring the old cylinder

To remove the old cylinder, insert the key into the locking cylinder first. Now turn the key slightly so that the cam is vertical, i.e. in “zero” position. Now loosen the fastening screw using a screwdriver. The key is fixed in the cylinder and the cylinder can thus be pulled out of the lock. If the cylinder jams, gently shake the key and pull the cylinder out. You can determine the cylinder dimensions by measuring the distance between the cylinder edge and the centre of the hole for the cylinder screw with a ruler. Perform this measurement on both sides, the outside and inside, and make a note of the values. The cylinder's internal (B) and external dimension (A) have now been measured. Always make sure that you do not mix up the inside and outside.

Option 2:

Determine cylinder length by measuring the door

Place an angle on the inner fitting. Now, measure the distance between the try square edge and the centre of the cylinder screw drill hole. You have now determined the inner dimension (B). Note this value and proceed the same way on the outside.

If there is no fitting, you can set the ruler directly on the door. Always make sure that you do not mix up the inside and outside.

How far can a cylinder protrude?

As a general rule, a locking cylinder should not protrude more than 3 millimetres.
Incorrect cylinder length increases the risk of burglary.
In the video below you will see detailed instructions again and also learn how to determine the Winkhaus cylinder type.