Introduction

Euro cylinder locks are very popular in mainland Europe but are becoming increasingly common in the United Kingdom. They are one of the most used locking systems on modern front doors, especially uPVC and composite types. Straightforward to measure and easy to replace, they’re ideal for anyone upgrading door security.

In this guide, you’ll learn how to measure your euro cylinder lock accurately, how to remove it, and how to install a replacement with minimal tools.

What Is a Euro Cylinder Lock?

A euro cylinder lock is a barrel-shaped mechanism that controls the locking function in many modern doors. It slots into a central lock case or multipoint locking strip and is secured with a single screw from the side of the door.

Euro cylinders come in three main types:

• Double Cylinder: Key-operated from both sides — ideal where locking/unlocking from both directions is needed.
• Thumbturn: Key on the outside, thumbturn on the inside. Often used on residential doors to allow safe internal exit without a key.
• Single Cylinder: Key-operated from one side only — typically used on garage or shed doors where internal locking isn’t required.

Euro 15 Pin Cylinder - Key to Turn - £77.50

Euro 5 Pin Double Cylinder - Key To Key - £19.50

How to Measure a Euro Cylinder Lock

Euro cylinders are measured by total length, which includes the 10mm-wide rotating cam in the centre. The sections on either side of the cam are the internal and external projections, usually equal in length — for example, 35/35 for a 70mm cylinder.

Some locks require offset measurements like 20/50 if the lock body isn’t centrally positioned in the door. Always measure from the centre of the cam to each end to get the correct size.

How to Choose the Correct Length of Euro Cylinder

Measure the thickness of the door and double the thickness of the door handles. Allow a slight projection (2–3mm) on each side of the handle plate to ensure the cylinder fits flush or just proud. This gives a clean look and avoids unnecessary overhangs that could weaken security.

Removing the Old Cylinder

Euro cylinders are easy to replace. Here’s how:

1. Open the door and locate the retaining screw on the door edge, aligned with the cylinder.
2. Use a Phillips screwdriver to remove the screw fully.
3. Insert the key, turn slightly (about 15°) to align the cam, then slide out the cylinder.
4. If it sticks, adjust the cam or loosen the door handle screws slightly for extra clearance.

Fitting the New Cylinder

1. Ensure the new cylinder matches the old one in size and type.
2. Insert the new lock into position, aligning the cam if necessary using the key.
3. Insert and tighten the retaining screw.
4. Test the lock from both sides before closing the door. Make sure the thumbturn is on the internal side if applicable.

Security Considerations

Not all euro cylinders offer the same level of protection. When upgrading, look for these features:

• Anti-snap: Designed to snap in a controlled way under attack, protecting the internal cam and keeping the door locked.
• Anti-pick and anti-drill: Include hardened internal components and more complex keyways to resist tampering.

For more details on home security, visit the West Yorkshire Police home security guide.

Conclusion

Replacing a euro cylinder lock is a quick and worthwhile upgrade. With just a tape measure and screwdriver, you can remove the old lock and fit a new, secure one in minutes. Always double-check sizing and security ratings before purchase. Browse our full Euro Cylinder Lock collection or read our guide to choosing the right front door lock for more help.

FAQ

Q: What is a euro cylinder lock?
A: It’s a lock barrel used in many modern doors. It controls the lock function with a key or thumbturn and fits into a central mechanism.

Q: How do I measure my cylinder?
A: Remove the lock and measure from the centre of the fixing hole to each end. If it’s 35mm on both sides, it’s a 35/35mm (70mm total). For uneven sizes, state both dimensions — e.g. 25/50.

Q: Can I replace a euro cylinder myself?
A: Yes — it’s a DIY job. Remove one screw, turn the key to align the cam, and slide it out. Fit the new one in reverse.

Q: What makes a lock “anti-snap”?
A: Anti-snap euro cylinders break in a controlled section under force, preventing access to the cam and maintaining the locked state.

Q: What is a keyed alike euro cylinder?
A: A keyed alike cylinder allows multiple locks to be opened with the same key — useful for front and back doors sharing one key.

Q: What is a keyed to differ euro cylinder?
A: Each lock has a unique key — no two are alike. Ideal when individual key access is needed for security or privacy.

Q: What is a euro cylinder master system?
A: A master system allows individual keys per door but includes one master key that opens all locks — commonly used in offices and shared buildings.