What Size Euro Cylinder Do I Need?
Choosing the correct Euro cylinder size is essential for both security and smooth daily use. But it can also be quite confusing, here at XFORT, we’re here to help you! Use this guide to measure your existing cylinder and buy the correct one for your needs.
How to Measure Your Euro Cylinder
Method One (Quick Check)
From the outside, measure from the centre of the fixing screw to the external edge (A).
From the inside, measure from the centre of the fixing screw to the internal edge (B).
Your cylinder size will be written as A/B — for example, 45/45.
Method Two (Most Accurate)
If you’re comfortable removing the cylinder, loosen the central fixing screw, turn the key slightly and slide the cylinder out.
Measure the full length end to end, then note the A/B split for ordering.
Tip: Method One is suitable for confident ordering in most cases. Method Two gives the most precise fit.
Do I Have a Double or Thumbturn Cylinder?
Double Euro Cylinder
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Keyhole on both sides of the door
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Locked and unlocked with a key from inside and outside.
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Common on front and back doors where maximum security is the priority.
You have a double cylinder if there’s a keyhole on both sides of your handle.
Thumbturn Euro Cylinder
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Keyhole on the outside.
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Thumbturn on the inside for quick and easy locking and unlocking without a key.
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Popular for flats, internal entrance doors and shared spaces where fast exit and convenience matter.
You have a thumbturn cylinder if the inside has a small turning knob instead of a keyhole.
Can You Switch Between a Double and Thumbturn Cylinder?
Yes, in most cases, you can easily switch between a double and a thumbturn Euro cylinder, as both use the same standard profile and fixing method. The key factor is ensuring you order the correct A/B size to match your existing cylinder.
Switching from a Double to a Thumbturn:
This is a popular upgrade for those who want to lock and unlock the door from the inside without using a key. It’s particularly useful in family homes, shared spaces or flats where quick exit is important.
Switching from a Thumbturn to a Double:
If you prefer or require a lockable cylinder from both sides (for example, for higher external security or compliance reasons), you can replace a thumbturn with a double cylinder of the same size.
Note: Some communal entrance doors, rented flats or fire escape routes may have specific regulations about internal thumbturns, so it’s worth checking before switching.
Should I Choose Keyed Alike Cylinders?
If you have more than one door, keyed alike cylinders allow you to use one key across multiple locks. This keeps things simple, especially for homes with both front and back doors or several external entries.
The XFORT Colossus line is available in keyed alike, so you can combine high security with everyday convenience.
Which XFORT Cylinder Is Right for My Door?
XFORT Colossus Euro Cylinder – For Ultimate Security
The Colossus range is designed for maximum protection on main external doors, with advanced security features for peace of mind.
Key Features:
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3 Star, BSI Kitemarked and Secured by Design certified (selected models).
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Anti-snap, anti-drill and anti-bump protection.
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Available in double and thumbturn options.
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Can be supplied keyed alike for multi-door convenience.
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XFORT Standard Euro Cylinder, For Internal and Low-Risk Doors
For internal doors, garages and areas where high protection isn’t required, the XFORT Standard cylinders are a practical choice. They provide smooth operation and reliable performance at a more economical price, ideal for everyday internal use.
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In Summary
Measure your existing lock using A/B sizing, check whether you have a double or thumbturn cylinder, and choose the type that best suits your needs.
You can easily swap between the two if the measurements match.
For high security and keyed alike convenience, choose the XFORT Colossus Euro Cylinder.
For internal or secondary doors, or a more budget option choose the XFORT Standard Euro Cylinder for dependable performance at great value.