How to Fit a Smart Lock to a UK Door
Fitting a smart lock to a standard UK door is a straightforward DIY job that takes around 30 minutes with basic tools. This guide covers the key measurements, compatibility checks, and step-by-step process to upgrade your home security.
Quick answer
For most UK doors, the Yale Linus Smart Lock is the easiest retrofit option, fitting over your existing euro cylinder without replacing the internal mechanism. The key is checking your door thickness (38-80mm) and ensuring you have a standard 5-lever mortice or euro cylinder lock.
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Research updated June 2026.
Yale Linus Smart Lock
Retrofits over existing euro cylinder, no new keys needed
What type of smart lock fits a UK door?
UK doors typically use either a euro cylinder lock (common on uPVC and composite doors) or a 5-lever mortice lock (common on wooden doors). Most smart locks are designed for euro cylinders, with some models offering mortice adaptors. The Yale Linus and August Smart Lock Pro both retrofit over existing cylinders, meaning you keep your original key for backup.
For mortice locks, the options are more limited. The Yale Conexis L1 is a popular choice that replaces the entire lock mechanism. Always measure your door thickness and backset (distance from edge of door to centre of lock) before buying.
What tools will you need?
Most smart lock kits include the necessary screws and adaptors. You will typically need a Phillips head screwdriver, a tape measure, and a pencil. Some installations may require a drill with a 25mm spade bit for the latch bolt hole, but many retrofit models avoid this entirely.
Having a spirit level on hand helps ensure the lock plate is perfectly aligned. A small file can also be useful if the existing hole needs slight enlarging for the new latch.
Step-by-step installation guide
Step 1: Check compatibility
Measure your door thickness. Most smart locks require 38mm to 80mm. Measure the backset (usually 45mm or 60mm for UK doors). Check the cylinder type: euro cylinders have a screw on the faceplate, mortice locks do not. If you have a euro cylinder, measure the length from the centre screw to each end.
Step 2: Remove the existing lock
For euro cylinders, remove the screw on the lock faceplate and slide the cylinder out. For mortice locks, unscrew the faceplate and remove the lock body from the door edge. Keep the screws safe as you may need them for the smart lock adaptor plate.
Step 3: Install the latch or adaptor
Most retrofit smart locks come with a replacement latch bolt or an adaptor that fits over your existing cylinder. Slide the adaptor over the cylinder tailpiece and reinsert the cylinder into the door. Secure with the faceplate screw. Ensure the adaptor rotates freely with the key.
Step 4: Mount the smart lock body
Attach the mounting plate to the door using the provided screws. Align the smart lock body over the adaptor and twist to lock into place. Some models use a magnetic coupling, others a mechanical spline. Follow the manufacturer's instructions for your specific model.
Step 5: Install the interior escutcheon
On the inside of the door, attach the interior escutcheon (the inside part of the lock). This usually clips or screws onto the mounting plate. Ensure the batteries are inserted correctly. Test the lock operation manually using the thumbturn.
Step 6: Pair with the app
Download the manufacturer's app and create an account. Follow the in-app instructions to pair the lock via Bluetooth or Wi-Fi. Set up your access codes, auto-lock timers, and any smart home integrations. Test the lock locks and unlocks correctly from the app.
What to check before buying
- Door material: uPVC, composite, and wooden doors all work, but check the manufacturer's compatibility list.
- Key override: Ensure the lock has a physical key backup in case of battery failure.
- Smart hub: Some locks require a separate hub for remote access and voice control.
- Battery type: Most use 4x AA batteries. Check the expected battery life and low battery alerts.
- Weather resistance: For external doors, look for IP44 rating or higher to protect against rain.
Mistakes to avoid
- Forgetting to measure the cylinder offset: Euro cylinders come in offset sizes (e.g. 35/35mm, 40/30mm). The smart lock adaptor must match your cylinder length.
- Ignoring the door alignment: If your door is warped or the strike plate is misaligned, the smart lock may jam. Fix the door first.
- Skipping the backup key test: Always test that the physical key still works after installation before relying on the smart features.
- Not checking the door swing: Some smart locks are handed (left or right opening). Ensure you buy the correct version.
- Over-tightening screws: This can strip the threads or crack the lock housing. Tighten until snug, then stop.
Best smart locks for UK doors
Yale Linus Smart Lock
Best OverallPros
- Keeps existing key and cylinder
- Simple 10-minute install
- Works with Apple HomeKit, Google, Alexa
Cons
- Hub needed for remote access
- Bulky on narrow doors
The Yale Linus is the most popular smart lock for UK doors because it retrofits over your existing euro cylinder. You keep your original key and lock mechanism, so there is no need to rekey or change your door. Installation takes around 10 minutes with just a screwdriver.
Owner reviews consistently praise the reliable Bluetooth connection and the auto-lock feature. The main downside is the need for the Yale Connect hub if you want to control the lock remotely or use voice assistants. Battery life is quoted at 6 months with normal use.
August Smart Lock Pro
Best for Multi-User HomesPros
- Built-in Wi-Fi, no extra hub
- Auto-unlock via geofencing
- Works with Airbnb and guest access
Cons
- Larger than Yale Linus
- App setup can be finicky
The August Smart Lock Pro is a strong alternative to the Yale Linus, particularly if you want built-in Wi-Fi without needing a separate hub. It uses the same retrofit design, fitting over your existing euro cylinder. The auto-unlock feature uses your phone's location to unlock the door as you approach.
Owner reviews highlight the excellent guest access features, including virtual keys and scheduled access. The lock is bulkier than the Yale, which can be an issue on narrower doors. Some users report occasional Bluetooth connectivity drops that require resetting the lock.
Yale Conexis L1
Best for Mortice LocksPros
- Works with mortice locks
- Keypad and fingerprint options
- Long battery life
Cons
- Requires full lock replacement
- More complex installation
The Yale Conexis L1 is a complete lock replacement, not a retrofit. It is one of the few smart locks that works with both euro cylinders and 5-lever mortice locks, making it ideal for older UK wooden doors. The lock offers keyless entry via a keypad, and optional fingerprint reader.
Owner reviews note the excellent build quality and the long 12-month battery life. The installation is more involved than a retrofit model, requiring removal of the entire existing lock mechanism. Some users find the app less polished than the Linus app.
Ring Smart Lock (2nd Gen)
Best for Ring EcosystemPros
- Integrates with Ring doorbells
- Auto-lock and auto-unlock
- Works with Alexa
Cons
- Requires Ring Bridge hub
- No HomeKit support
The Ring Smart Lock is designed for homes already using Ring doorbells and security cameras. It retrofits over your existing euro cylinder and integrates seamlessly with the Ring app, allowing you to see who is at the door and unlock it from the same interface.
Owner reviews appreciate the smooth integration with Ring devices and the reliable auto-lock feature. The main drawback is the need for the Ring Bridge hub, which adds to the cost. The lock does not support Apple HomeKit, limiting its appeal for iOS-only households.
Ultion Smart Lock
Best for SecurityPros
- Sold Secure Diamond rated
- Snap-proof cylinder design
- Includes smart bridge
Cons
- Expensive
- Requires professional fitting for some
The Ultion Smart Lock is the most secure option, carrying the Sold Secure Diamond rating, the highest security certification for locks in the UK. It replaces the entire euro cylinder with a snap-proof design that resists lock snapping, a common burglary method in the UK.
Owner reviews consistently rate the build quality and security as excellent. The lock includes a smart bridge for remote access and works with Alexa and Google. The main downsides are the higher price and the recommendation for professional installation due to the precise fitting required.
Comparison table
| Product | Best For | Type | Battery Life | Rating |
|---|---|---|---|---|
| Yale Linus | Overall | Retrofit | 6 months | 4.6/5 |
| August Smart Lock Pro | Multi-user | Retrofit | 3-6 months | 4.4/5 |
| Yale Conexis L1 | Mortice locks | Full replacement | 12 months | 4.3/5 |
| Ring Smart Lock | Ring ecosystem | Retrofit | 6 months | 4.2/5 |
| Ultion Smart Lock | Security | Full replacement | 12 months | 4.5/5 |
FAQs
Can I fit a smart lock to any UK door?
Most UK doors with a euro cylinder or 5-lever mortice lock can accept a smart lock, but you must check door thickness and backset measurements first.
Do I need a smart hub for a smart lock?
Some locks like the August Smart Lock Pro have built-in Wi-Fi, while others like the Yale Linus require a separate hub for remote access.
Will a smart lock work with my existing keys?
Retrofit models like the Yale Linus and August Smart Lock Pro work with your existing keys and cylinder, so you do not need to rekey.
How long does it take to install a smart lock?
Retrofit models take 10-20 minutes. Full replacement locks like the Yale Conexis L1 can take 30-60 minutes.
What happens if the batteries die?
All smart locks have a physical key override. Some also have a 9V battery backup terminal on the outside.
Can I use a smart lock on a metal or composite door?
Yes, but check the manufacturer's compatibility list. Some locks require specific adaptors for non-standard door materials.
Do smart locks work with Alexa or Google Home?
Most smart locks work with Alexa and Google Home, but some require a hub for voice control integration.
Are smart locks secure against lock snapping?
Only locks with a Sold Secure Diamond rating, like the Ultion Smart Lock, are tested against lock snapping. Standard smart locks may not offer this protection.
Can I fit a smart lock to a uPVC door?
Yes, uPVC doors with a euro cylinder are the most common application for retrofit smart locks like the Yale Linus.
Do I need to drill new holes in my door?
Retrofit models require no drilling. Full replacement models may require drilling for the latch bolt and faceplate screws.
How many users can I add to a smart lock?
Most smart locks allow unlimited virtual keys via the app. The August Smart Lock Pro is particularly good for managing guest access.
What is the warranty on smart locks?
Most smart locks come with a 1-2 year warranty. Yale and Ultion offer 2 years on their smart lock products.
Our verdict
For most UK homes, the Yale Linus Smart Lock is the best overall choice due to its simple retrofit