Can I replace a euro cylinder myself?

Technically yes — it involves removing one screw and sliding the old cylinder out. However, getting the correct size is where most people go wrong. If you order the wrong size online, you are stuck waiting for a replacement. I carry a full range of sizes in my van and can fit the correct one in a single visit, so it often works out simpler and faster to call a locksmith.

What size euro cylinder do I need?

The size depends on your specific door. You need to measure from the centre of the fixing screw hole to each end of the cylinder. Most residential doors in Coventry use cylinders between 70mm and 100mm total length, but the split between inside and outside measurements varies. Call 07735 336175 and I will measure it as part of the job.

Should I get a thumbturn or double cylinder?

For most front doors, I recommend a thumbturn cylinder because it allows you to exit quickly without a key in an emergency such as a fire. The exception is if your door has a letterbox or glass panel near the lock, where someone could reach through and turn the thumbturn. In that case a double cylinder or a letterbox restrictor is a better option.

How long does it take to replace a euro cylinder?

A straightforward euro cylinder replacement takes about 15 to 20 minutes including testing. If the multipoint lock mechanism itself has a fault, it can take longer, but I will always let you know before starting any additional work.

Euro Cylinder Locks Explained: Sizes, Types, and How to Measure Yours

Euro cylinders are fitted to almost every uPVC and composite door in Coventry. Here is how they work, how to measure yours for replacement, and which type you should buy.

What Is a Euro Cylinder Lock?

A euro cylinder is the removable lock barrel that sits inside a uPVC or composite door's multipoint locking mechanism. It's the part you put your key into. When you turn the key, it rotates a small metal cam that engages the multipoint lock — shooting bolts into the top, bottom, and side of the door frame.

I'm Ross, a Coventry locksmith, and I work with euro cylinders every single day. They're the most common lock type on residential doors in the UK by a wide margin. If you have a uPVC or composite door — and most homes in Coventry do — you have a euro cylinder.

Types of Euro Cylinder

There are three main types, and knowing which one you have matters when it comes to replacement.

Single Euro Cylinder

A single euro cylinder has a keyhole on one side only. The other side is blank. These are typically used on doors where you don't need key access from both sides — garage doors, some back doors, and certain commercial applications. They're less common on front doors.

Double Euro Cylinder

A double euro cylinder has a keyhole on both sides — inside and outside. This is the standard type fitted to most uPVC and composite front doors in the UK. You need a key to lock and unlock from either side.

The downside: if there's a fire and you can't find your key, you can't get out. This is a genuine safety concern, and it's why I often recommend thumbturns instead when customers ask me about [lock changes](/services/lock-change).

Thumbturn Euro Cylinder

A thumbturn cylinder has a keyhole on the outside and a thumbturn knob on the inside. You lock and unlock from inside by turning the knob — no key needed. This is the type I recommend for most front doors because it balances security with fire safety.

The one caveat: if your door has a letterbox or glass panel close to the lock, a thumbturn can be a vulnerability. Someone could reach through and turn it. In those cases, I'd suggest either a double cylinder or fitting a letterbox restrictor.

How to Measure a Euro Cylinder

Getting the right size cylinder is critical. Too short and the lock won't engage properly. Too long and the cylinder will protrude from the door, making it easier to [snap](/blog/what-is-lock-snapping).

Here's how to measure yours step by step:

**Remove the existing cylinder.** Open the door, find the screw on the edge of the door (on the faceplate of the multipoint lock, roughly level with the cylinder). Undo that screw completely.

**Turn the key slightly** — about 10-15 degrees — so the cam retracts, then pull the cylinder out from either side.

**Measure from the screw hole to each end.** This is the critical measurement. You'll get two numbers — for example, 40mm outside and 45mm inside. That makes it a 40/45 cylinder (total length 85mm).

**Note down both measurements.** The outside measurement (from screw hole to the exterior end) and the inside measurement (from screw hole to the interior end) are almost always different.

Important: measure from the centre of the screw hole to each end. And measure the actual cylinder, not the key.

If you're not confident measuring it yourself, call me on 07735 336175 and I'll come out and measure it as part of the job. I carry a wide range of sizes in the van, so I can almost always fit the right one on the first visit.

Common Sizes in Coventry

Most uPVC doors in Coventry use cylinders in the 35/35 to 50/50 range. The exact size depends on the door profile and handle position. Composite doors tend to need slightly different sizes depending on the manufacturer — Rockdoor, Solidor, and Endurance all vary.

New-build homes around [Canley](/areas/canley), [Whitley](/areas/whitley), and the Keresley developments often use 40/40 or 45/45 cylinders, but I always measure on-site because assumptions lead to wasted time and money.

Major Euro Cylinder Brands

Not all euro cylinders are created equal. Here's a rundown of the main brands I work with:

Yale

Yale is the most recognised lock brand in the UK. Their euro cylinders range from basic (avoid these) to the Platinum 3-Star range, which offers genuine anti-snap protection. The mid-range Yale Superior is decent value but doesn't carry the top security certifications.

ERA

ERA makes budget to mid-range cylinders. Their Fortress cylinder is reasonable for the price, but for a front door I'd generally recommend spending a bit more on something with better anti-snap credentials.

Avocet ABS

The Avocet ABS (Anti Bump & Snap) range is excellent. The ABS MK3 is one of my go-to recommendations — it carries TS007 3-star certification, offers anti-snap, anti-bump, anti-pick, and anti-drill protection, and comes with a solid warranty. I compare it in detail in my [anti-snap locks comparison](/blog/anti-snap-locks-compared).

Ultion

Ultion is the premium option. It's TS007 3-star rated on its own (the cylinder achieves all 3 stars without needing additional hardware), and it comes with a £2,000 guarantee if your home is broken into through an Ultion-protected door. It's more expensive, but for a front door, the peace of mind is worth it.

ABS by Avocet

A step up from the standard Avocet range, these are particularly good value. I fit a lot of these across Coventry and they've got an excellent track record.

When to Replace Your Euro Cylinder

You should consider a [lock change](/services/lock-change) or [upgrade](/services/lock-upgrade) if:

Your cylinder is more than 10 years old

You've moved into a new property and don't know who has keys

Your key is stiff or difficult to turn

The cylinder has no anti-snap protection (see my guide on [lock snapping](/blog/what-is-lock-snapping))

You've had a break-in or attempted break-in

Your insurance company requires a higher-security lock

I change euro cylinders across Coventry from £69. Give me a call on 07735 336175 or check the [prices page](/prices) for full details.

A Note on Quality

I've lost count of the number of times I've turned up to a job and found a £5 euro cylinder from a DIY store fitted to someone's front door. These cylinders are made from cheap zinc alloy, have no security features, and can literally be snapped with bare hands. Your front door lock is the primary barrier between your home and a burglar. Spend the money on a decent one. It's one of the cheapest and most effective security investments you'll ever make.