How to Change a Euro Cylinder Lock

Last Updated: October 24, 2026

Table of Contents

• What You'll Need Before Starting
• How to Measure a Euro Cylinder Lock Correctly
• Understanding Euro Cylinder Lock Sizes
• How to Remove a Euro Cylinder Lock from Your Door
• Step-by-Step Process to Change Your Euro Cylinder Lock
  • Step 1: Locate and access the lock
  • Step 2: Remove the retaining screw
  • Step 3: Extract the old cylinder
  • Step 4: Insert the new cylinder
  • Step 5: Secure with the retaining screw
  • Step 6: Test the new lock
• Common Mistakes to Avoid When Changing Your Lock
• When to Call a Professional Locksmith
• Frequently Asked Questions

What You'll Need Before Starting

Learning how to change a euro cylinder lock is straightforward if you have the right tools and materials. Before you start, gather everything you'll need so you're not hunting for items mid-job.

You'll need a screwdriver (usually slotted or Phillips, depending on your lock's retaining screw), the new euro cylinder lock, and possibly a torch for better visibility inside the door. Some people find needle-nose pliers helpful for gripping small parts, though they're optional.

Check your door's current lock to see what size cylinder you have. Understanding different residential door lock types helps you choose the correct replacement. Residential Door Locks: Types, Installation & Security explains the various options available so you can ensure you're selecting the right replacement cylinder for your door.

Keep the old cylinder handy until you've tested the new one. You might need to refer back to it if something doesn't fit properly.

Tools you'll need:

• Screwdriver (slotted or Phillips)
• Torch or good lighting
• Measuring tape
• Needle-nose pliers (optional)
• New euro cylinder lock

Materials:

• Replacement euro cylinder lock
• Small container for screws (so you don't lose them)

How to Measure a Euro Cylinder Lock Correctly

Measuring your euro cylinder lock correctly is essential before buying a replacement. An incorrectly sized cylinder won't fit your door, and you'll waste time and money.

The measurement runs from the centre of the screw hole on one side to the centre of the screw hole on the other side. This is called the overall length. Most euro cylinders measure between 30mm and 120mm, though 70mm and 80mm are the most common residential sizes.

To measure accurately, use a measuring tape or ruler. Place it against the cylinder's face and measure horizontally from the middle of one screw hole to the middle of the other. Write this number down. Many people get this wrong by measuring the visible part of the cylinder instead of the full length, so double-check your measurement.

You can also measure by removing the old cylinder first, then measuring it directly. This removes any guesswork and ensures you buy the exact size you need.

Understanding Euro Cylinder Lock Sizes

Euro cylinder locks come in standard sizes, and knowing which one you have prevents costly mistakes. The size determines whether the lock will function properly in your door.

Common euro cylinder lock sizes include:

• 30mm (rarely used in residential properties)
• 40mm (small doors or cupboards)
• 50mm (less common)
• 60mm (standard for some older doors)
• 70mm (most common residential size)
• 80mm (standard for many modern doors)
• 90mm (larger doors)
• 100mm and above (commercial or oversized doors)

The size you need depends on your door's thickness and the existing lock's dimensions. If you're unsure, measure your current cylinder or contact a professional. Buying the wrong size means a wasted trip to the shop and a delayed project.

Euro cylinder locks come in standard sizes, each suited to different door types and thicknesses.

How to Remove a Euro Cylinder Lock from Your Door

Before installing a new euro cylinder lock, you must remove the old one safely. This step is simpler than many people expect.

Locate the small retaining screw on the inside of the door, near the lock handle. This screw holds the cylinder in place. Using your screwdriver, turn it anticlockwise until it's loose enough to remove by hand. Don't force it; if it's stuck, apply a small amount of penetrating oil and wait a few minutes.

Once the screw is out, grasp the cylinder firmly and pull it straight out towards you. It should slide out smoothly. If it resists, check that the screw is fully removed and try again. Never twist or force the cylinder, as this can damage the door's internal mechanism.

Keep the screw in a safe place. You'll need it to secure your new cylinder.

Step-by-Step Process to Change Your Euro Cylinder Lock

Changing your euro cylinder lock takes about 10 to 15 minutes once you're familiar with the process. Follow these steps carefully to avoid mistakes.

Step 1: Locate and access the lock

Find the retaining screw on the inside of your door, just behind the lock handle. You may need a torch to see it clearly, especially in dim lighting. The screw is usually small and sits horizontally across the cylinder's body.

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Step 2: Remove the retaining screw

Using your screwdriver, turn the retaining screw anticlockwise. Turn slowly and steadily. If the screw is tight or stuck, don't force it. Apply a little penetrating oil, wait a few minutes, then try again. Once loose, remove it completely and set it aside safely.

Step 3: Extract the old cylinder

Grip the cylinder firmly with your hand and pull it straight towards you. It should slide out smoothly. If it doesn't budge, double-check that the screw is fully removed. Never twist or yank the cylinder, steady, firm pressure works best.

Step 4: Insert the new cylinder

Take your new euro cylinder lock and align it with the hole. Slide it in straight, ensuring it sits flush against the door. The cylinder should slide in as smoothly as the old one came out. If it feels tight, stop and check the alignment. Forcing a misaligned cylinder can damage both the lock and the door.

Step 5: Secure with the retaining screw

Once the new cylinder is in place, insert the retaining screw through the hole and into the cylinder. Turn it clockwise with your screwdriver until it's snug. Don't over-tighten, just firm enough that the cylinder can't wiggle.

Step 6: Test the new lock

Before finishing, test your new lock thoroughly. Insert your key from the outside and turn it both ways. The lock should turn smoothly without grinding or sticking. Try it from the inside as well. Open and close the door several times to ensure everything works properly.

Common Mistakes to Avoid When Changing Your Lock

Many people rush through the process of how to change a euro cylinder lock and run into preventable problems. Knowing what to avoid saves time and frustration.

The biggest mistake is forcing components that don't fit. If the new cylinder won't slide in smoothly, stop immediately. Check the size, alignment, and any obstructions. Forcing a misaligned cylinder damages the door and the lock mechanism.

Another common error is over-tightening the retaining screw. This can crack the cylinder or strip the screw hole. Tighten until snug, then stop. The screw only needs to hold the cylinder in place, not crush it.

Many people also forget to test the lock before declaring the job done. Always test both sides with your key and through a full open-close cycle. Discovering a problem after you've put your tools away is frustrating.

Watch out for mixing up screw sizes. If you're replacing multiple locks, label each screw so you don't accidentally use the wrong one in the wrong door. Some doors have slightly different screw sizes.

Common mistakes:

• Forcing a misaligned cylinder
• Over-tightening the retaining screw
• Skipping the test before finishing
• Using the wrong size cylinder
• Not measuring correctly before buying

When to Call a Professional Locksmith

Some situations call for professional help, even if you're confident with basic lock work. Knowing when to stop and call someone saves money and prevents damage.

If your cylinder won't budge after applying penetrating oil and waiting, stop. Forcing a stuck cylinder risks damaging your door. A professional locksmith has specialised tools and experience to remove stuck cylinders safely.

If you're unsure about your door's lock type or size, call a professional before buying a replacement. Getting the wrong size wastes money and time. A locksmith can measure your door accurately and recommend the right lock for your property.

If your door has a damaged lock mechanism or the cylinder won't sit flush after insertion, professional help prevents further damage. Trying to force a problem lock can crack the door frame or strip internal mechanisms.

If you need upgraded security, such as anti-snap locks for your rental properties, a professional locksmith can advise on the best options. Learn more about Benefits of Installing 3-Star Locks: Security Explained and explore 5 Best Practices for Home Security to understand what protection suits your needs.

At WS Locksmiths, our fully trained and vetted locksmiths handle everything from simple cylinder changes to complex security upgrades. If you're uncomfortable tackling the job yourself or encounter any problems, we're available 24/7 to help. Call us 24/7: +44 77321 89721.

Changing a euro cylinder lock is manageable for most homeowners, but it requires care and the right approach. If you encounter resistance, uncertainty, or damage during the process, professional support prevents costly mistakes. WS Locksmiths provides expert guidance and swift installation when you need it, ensuring your home stays secure without the stress of DIY complications.

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