How to measure and fit your door cylinder

How to measure and fit your door cylinder

How do I measure a Upvc door cylinder Lock?

The size of cylinder you need is determined by the thickness of the door and handle combination, for this reason there are many sizes available and you will need to be careful that you measure the cylinder accurately (one size will not fit all).

It is possible to measure a door cylinder in the door, but to be sure it's best to remove it first.


Measurement A - Measure from one end of the cylinder to the middle of the central screw hole (e.g. 40mm).

Measurement B - Measure from the other end to the middle of the central screw hole (e.g. 45mm).

This would be a 40/45 cylinder (85mm in length). No further measurements are required.

This applies to all our cylinder locks including thumbturns

How do I fit a new door cylinder?

  • Open the door and unscrew the one fixing screw which is located on the lock faceplate (the strip of metal the full length of your door), in line with the bottom of the door cylinder.
  • Put the key into one side whilst holding the other side firm.
  • Turn the key and the cylinder should slide out, if it does not turn the key in the opposite direction and the cylinder should slide out.
  • Take your new cylinder lock and insert the new key and turn it until the cam is inline with the body of the cylinder. Insert the new cylinder into position and replace the fixing screw.
  • If the door cylinder is offset (i.e. 40/60, 30/50 etc) ensure the off set is protruding from the correct side. Check the operation of the lock before you close the door.

How far should a door cylinder protrude out of the door handle?

Your new door cylinder should protrude between 2mm and 5mm from the handle back plates, but due to the overall lengths of cylinders available this is not always possible. It is most sensible to go for exactly the same size as you are replacing (unless your old cylinder was protruding excessively).

Can I get keys cut locally for cylinders?

Almost all local key cutting shops carry key blanks to fit our locks.


To keep your locks in excellent working order we recommend Silicone Spray Lubricant & Cleaner