How to Measure and Change a Door Cylinder

04 October 2021

At SD Hardware we believe that being able to measure and change a door cylinder is as useful as knowing how to change a car tyre. Not only is it a basic and useful skill to learn, but it could also save you a hefty bill from a locksmith should your cylinder become broken or damaged through general wear and tear or in the event of a break-in, costing you up to £150 should your cylinder need replacing. But don't worry because we've got you covered with our step-by-step guides on how to measure your cylinder and how to change a door cylinder.

Before you change your door cylinder you'll need to purchase a new cylinder and if you're looking for matching door furniture our range of door hardware will give you a variety of options to choose from. But first, it's important to ensure you've measured up your cylinder correctly to purchase the right size for your door.

To measure your door cylinder simply measure from the centre of the fixing point (where the machine screw fits) on the cylinder to the internal edge and then do the same on the outer edge.

An example of common cylinder sizes include:

35-35 - typically used on a 44mm thick door
40-40 - typically used on a 56 or 58mm thick door
35-45 - typically used on a 56 or 58mm thick door but offset

For a simple explanation watch our video on How to Measure a Door Cylinder.

There are many reasons why your door cylinder may need changing including (but not limited to):

Old, worn, and difficult to use locks
Damage from a break-in or attempted break-in
Matching all your doors to a keyed alike version so one key opens all your doors (please see our quick video ref Keyed alike cylinder)
Moving house and ensuring that the previous homeowners or tenants cannot gain access if they didn't give their key back
If you've ever lent your key to anyone (and no longer want them gaining access or worried they may have made a copy)
A key has been lost and you're worried about your home security
Aesthetic reasons, for example, you have changed the finish of your door handle and want to match the finish of your cylinder to your handles

The good news is, it'll take only 5 minutes to change your door cylinder, and that's much quicker and a big saving on what a locksmith could charge you! All you need is a screwdriver and your new cylinder.

Here's our quick and easy step-by-step guide:

Locate the screw which is directly below the deadbolt on the multipoint lock and remove it to release the cylinder. But make sure you keep it safe as although all new cylinders come with 1 or two machine screws you may need it again!
Remove the cylinder by slightly turning the key to line up the cam with the cylinder housing, this will allow you to easily pull the cylinder out.
Insert your new cylinder, again using the key to line up with the cam and push it into place
Insert the fixing screw and tighten as much as you can to secure the cylinder
And finally, check your new cylinder works!

Choosing the right type of door cylinder is important as it will determine how secure your home is. The SD Hardware range of Euro Door Cylinders will fit all multipoint door locks and our comprehensive collection includes a range of options to choose from including High Security 3 Star Cylinders, Keyed Alike (Singles), Keyed Alike (Pairs), Thumbturn Cylinders, and Easy Access Thumbturns Cylindersin a range of sizes and finishes to match your door furniture: Black, Nickel, or Brass.

But what cylinder is right for you? Here are a few types of cylinders that may be suitable for your home.

Double Cylinder: Double cylinder locks have a key cylinder on both sides of the door. This means a key can be used to lock and unlock the door from either side. This lock format is usually used for doors requiring higher security, such as front or back doors. In the event a burglar broke the glass in your door, a key would still be required to unlock the door. The police recommend this type of cylinder over a thumb turn as it is more likely to prevent break-ins as you need a key to unlock either side.

Thumb Turn Cylinder: This type of cylinder works well on front doors, back doors, or patio doors. The cylinder is locked by a key on the outside of the door, while on the inside all you need to do is twist the thumb turn to lock or unlock. A Thumb turn cylinder is useful in an emergency when a quick exit is required (for example a fire) - simply twist the thumb turn and the door will unlock with no requirement for a key.

Offset Cylinder: Most homes require cylinders that are equal, which means from the centre screw hole, each side is exactly the same dimension. However, if you require an Offset Cylinder, the external size to centre and internal size to centre are different lengths. This type of cylinder is most commonly used on UPVC or composite doors and comes in a huge range of various sizes, we can source most sizes required, contact our sales team if you cannot find your required size.

Half or Single Cylinders: This type of cylinder is perfect for doors requiring keyed access from one side only. One common area of use is on the bottom door on stable doors to give the door a sleek look from the outside and negating the need for keyed alike cylinders. These locks are usually used for keyed access from the exterior, for example on garage doors or storerooms. Alternatively, Half thumb-turn cylinder locks enable a quick, key-free exit and lock from one side only. These locks can be useful for scenarios in which a key is considered inconvenient. They may also be used for privacy reasons, for example in bathrooms.

Keyed Alike Cylinders: At SD Hardware, we offer a keyed alike service that is bespoke to your home and doors. This service allows for one key to fit multiple locks within a building, for example, your front door and back door can be locked and unlocked using the same key.

Our Keyed Alike Cylinder service makes it easy to create your own custom cylinder lock and key solution and the benefits are second to none with the ability to allow one key per family member to unlock the front door, kitchen, and patio doors.

The possibilities are endless when it comes to door cylinders with a wide range of types and sizes to choose from. View our comprehensive range of door cylinders to find your perfect fit and follow our tips above to measure and change your cylinder in a few simple steps knowing that your bank balance will be safe should you need to change a cylinder with no unnecessary locksmith fees.

If you can't find the type, finish, or size you are looking for then please contact our friendly sales team who will assist you in finding the correct door cylinder.