I Need a New Door Lock – Here's How to Choose the Right One"
Replacing a door lock sounds simple — until you're standing in front of a wall of options wondering what the difference is between a euro cylinder and a mortice lock. If you've typed "I need a new door lock" into Google, you're in the right place.
Why do door locks need replacing?
Locks wear out over time, get damaged, or simply become a security risk. Common reasons to replace yours include:
- Lost or stolen keys (always replace immediately)
- A lock that's stiff, sticking, or difficult to turn
- Moving into a new home
- Upgrading to a higher security rating
- A damaged or broken lock mechanism
What type of lock do you have?
Before buying a replacement, you need to know what type of lock is fitted to your door.
Euro Cylinder Locks are the most common type on modern uPVC and composite doors. They're the oval-shaped lock that your key goes into directly. To replace one, you simply need to measure the cylinder size.
Mortice Locks are fitted inside the door itself and are common on timber doors. They require a key that goes through the door handle or a separate keyhole.
Rim Locks (also called nightlatches) are surface-mounted on the inside of the door — the Yale-style lock is the most familiar example.
How to measure your euro cylinder
If you have a euro cylinder, measuring correctly is crucial — get it wrong and the lock won't fit. Here's what to do:
- Open your door and remove the lock by unscrewing the central screw through the door handle
- Measure from the centre of the screw hole to the outside edge — this is your external measurement
- Measure from the centre of the screw hole to the inside edge — this is your internal measurement
- Your cylinder size is written as external x internal (e.g. 35/45)
What security rating should I look for?
Look for locks that are TS007 3-star rated or Sold Secure Diamond certified. These meet the standards required by most home insurance policies and offer significantly better protection against snapping, picking, and drilling attacks.
Ready to find your replacement lock?
Browse our full range of euro cylinders and door hardware at FrameLock Hardware — all with clear sizing guides and fast UK delivery.
https://framelockhardware.co.uk/collections/door-cylinders
