What is the most common euro cylinder size for uPVC doors in Coventry?

The most common size I encounter across Coventry is 40/40 (80mm overall). This fits the majority of standard uPVC doors on estates built from the late 1990s to the 2010s. Older doors may use 35/35, and thicker composite doors often need 45/45. The only way to be certain is to measure your existing cylinder using the steps in this guide, or call me on 07735 336175 and I will measure it for you.

Can I measure my euro cylinder without removing it from the door?

You can get a rough measurement by measuring the door thickness and subtracting a few millimetres for the handle and escutcheon on each side, but this is not reliable. The only accurate way is to remove the cylinder by undoing the fixing screw on the door edge, turning the key slightly to align the cam, and pulling the cylinder out. Then measure from the screw hole to each end. It takes five minutes and avoids buying the wrong size.

What happens if my euro cylinder sticks out past the handle?

If the cylinder protrudes more than 3mm beyond the handle or escutcheon on the outside of your door, it is vulnerable to lock snapping. A burglar can grip the protruding section with pliers, snap it off, and then manipulate the remaining mechanism to open the door — often in under 30 seconds. If your cylinder sticks out, you need a shorter replacement or a proper anti-snap cylinder urgently. Call 07735 336175 for a same-day upgrade.

Do I need to buy the same brand of euro cylinder as my current one?

No. Euro cylinders are standardised, so any correctly sized cylinder will fit your door regardless of the original brand. What matters is the measurements (outside length, inside length, and type) and the security rating. I recommend upgrading to an anti-snap cylinder like the Ultion or ABS Avocet regardless of what brand you currently have. See our euro cylinder upgrade guide for detailed comparisons and prices.

How to Measure a Euro Cylinder for Your uPVC Door (with Pictures)

Buying the wrong size euro cylinder is the number one DIY mistake with uPVC doors. Here is exactly how to measure yours — step by step with pictures.

Why Getting the Right Measurement Matters

If you need to replace the euro cylinder on your uPVC door — whether it has been snapped, is getting stiff, or you simply want to upgrade to an anti-snap model — the first thing you need is the correct size. Buy the wrong cylinder and it either will not fit, will stick out dangerously from the door (making it easier to snap), or will sit too far recessed for the key to turn properly.

I replace euro cylinders across Coventry every week, and the most common problem I see with DIY attempts is people buying the wrong size. This guide will walk you through exactly how to measure yours, step by step. If you would rather skip the measuring and have me supply and fit the right one, call 07735 336175 — I carry a range of sizes in my van.

What You Will Need

A Phillips or flat-head screwdriver

A tape measure or ruler (millimetre accuracy)

Your door key

A pen and paper or your phone to note measurements

Step-by-Step: How to Remove and Measure Your Euro Cylinder

Step 1: Locate the Fixing Screw

Open your uPVC door and look at the edge (the narrow strip that faces into the frame when closed). You will see a long metal faceplate with various bolts and latches. Find the single screw that sits roughly in line with the keyhole — this is the cylinder fixing screw. It is usually a longer screw than the faceplate screws around it.

Step 2: Remove the Fixing Screw

Unscrew the fixing screw completely and set it aside. Do not lose it — you will need it to secure the new cylinder.

Step 3: Remove the Cylinder

This is where people sometimes get stuck. The cylinder will not just pull out — you need to turn the key slightly (about 10 to 20 degrees) so that the cam (the small metal tongue on the back of the cylinder) aligns with the slot in the mechanism. With the key turned slightly, you can then pull or push the cylinder out from either side of the door.

If the cylinder is really stuck, try wiggling the key gently while applying steady pressure. Do not force it — if it will not budge, the cam may not be aligned correctly. Keep adjusting the key angle until it slides out.

Step 4: Measure From the Screw Hole to the Outside End

Lay the cylinder on a flat surface. You will see the screw hole in the middle section of the cylinder. Measure from the centre of this screw hole to the end that faces outside your door. Note this measurement in millimetres.

Step 5: Measure From the Screw Hole to the Inside End

Now measure from the centre of the screw hole to the other end — the side that faces inside your home. Note this measurement separately.

Step 6: Determine the Cylinder Size

Your cylinder size is expressed as two numbers: outside measurement / inside measurement. For example, if the outside measures 35mm and the inside measures 35mm, you have a 35/35 cylinder (70mm overall). If the outside is 40mm and the inside is 45mm, you have a 40/45 cylinder.

Step 7: Note the Cylinder Type

Check whether your cylinder is:

**Key/Key** — a keyhole on both sides (most common for front doors)

**Key/Thumbturn** — a keyhole on the outside and a thumbturn on the inside (increasingly popular, and I recommend these for most homes — see our [lock change service](/services/lock-change) for fitting options)

Common Euro Cylinder Sizes for Coventry Doors

Having fitted cylinders in thousands of Coventry homes, these are the sizes I encounter most often:

**35/35 (70mm overall)** — common in older uPVC doors from the 1990s and early 2000s, typical in areas like Tile Hill and Canley

**40/40 (80mm overall)** — the most common size in standard uPVC doors across Coventry estates

**45/45 (90mm overall)** — found in thicker composite doors and some newer uPVC doors

**35/45 (80mm overall)** — asymmetric size, common where the door is thicker on one side or has a decorative panel

The most important thing is that the cylinder sits flush with the door furniture (handles and escutcheons) on both sides. If the cylinder sticks out beyond the handle or escutcheon by more than 3mm on the outside, it is vulnerable to lock snapping. This is a serious security risk — read our guide on [what is lock snapping](/blog/what-is-lock-snapping) to understand why.

What Happens If You Buy the Wrong Size

Too Long

If the cylinder is too long, it will protrude from the door face. On the outside, this creates a snapping risk — a burglar can grip the protruding cylinder with pliers or a wrench and snap it. On the inside, it just looks wrong and may foul against the thumbturn or handle.

Too Short

If the cylinder is too short, it will sit recessed inside the door. The key may not reach properly, or the cam may not engage with the mechanism correctly. In some cases, the key will turn but the lock will not actually operate — extremely frustrating if you have just fitted a brand new cylinder.

Wrong Type (Key/Key vs Key/Thumbturn)

This is not the end of the world — the cylinder will still fit — but a thumbturn where you expected a key (or vice versa) is inconvenient and may not match your needs. If you are upgrading, I generally recommend key/thumbturn for most residential doors as it allows quicker exit in an emergency.

Where to Buy the Right Cylinder

You have several options:

**Online** — sites like eBay, Amazon, and specialist lock shops stock a huge range. Make sure you buy a branded, anti-snap cylinder (see our [best euro cylinder upgrades for 2026](/blog/best-euro-cylinder-upgrades-2026) for recommendations).

**Local hardware shops** — B&Q and Screwfix carry basic cylinders but the anti-snap range is limited.

**Call me** — I supply and fit quality anti-snap cylinders (Ultion, ABS, Yale Superior) at competitive prices, and I guarantee the correct size. One call to 07735 336175 and the job is done, usually within the hour.

A Word on Security When Measuring

If you are measuring your cylinder because you want to upgrade to an anti-snap model, make sure the new cylinder meets at least these criteria:

**Anti-snap** — the cylinder has a sacrificial cut line so that if someone tries to snap it, the front section breaks away without exposing the locking mechanism

**Anti-drill** — hardened steel pins resist drilling

**Anti-bump** — internal design prevents bump key attacks

**Anti-pick** — complex pin configurations resist picking

All of the cylinders I fit as standard meet these criteria. For a detailed comparison of the best options, see our [euro cylinder upgrade guide](/blog/best-euro-cylinder-upgrades-2026).

Should You Measure Yourself or Call a Locksmith?

If you are comfortable with a screwdriver and a tape measure, measuring your own cylinder is straightforward. The steps above are all you need. Where it gets complicated is sourcing the right replacement — making sure the brand is genuinely anti-snap, the size is exactly right, and the quality is decent.

If you would rather not risk it, give me a call on 07735 336175. I cover all of Coventry and the surrounding areas — Kenilworth, Warwick, Leamington, and everywhere in between. Check our [areas page](/areas/) for full coverage. I will measure, supply, and fit the correct cylinder in one visit, and the total cost including a quality anti-snap cylinder is typically between £59 and £89 depending on the brand and size.

For more on uPVC door locks and maintenance, see our [uPVC door maintenance guide](/blog/upvc-door-maintenance-guide) and our [uPVC lock repair service page](/services/upvc-lock-repair).