Keyed Alike vs Master Key System: Which is Best?

Master key system - bunch of keys

When it comes to managing keys for multiple doors, a professional locksmith can usually offer two main options:  keyed alike and master key systems. Both are good solutions, but understanding their differences is crucial for making the right decision for your needs.

Keyed Alike

Imagine a single key that opens every door in your house. That’s the basic idea of a keyed alike system. All the locks within the system share the same internal mechanism, allowing one key to operate them. (One key fits all)


  1. Convenience: No more hunting around for the right key – one key unlocks everything. This is perfect for homes, small offices, or storage units with multiple doors.
  2. Cost-Effectiveness: The initial investment is lower compared to master key systems due to the simpler lock design.
  3. Easy Key replacement: Duplicate keys are easily obtainable, making replacements readily available when needed.


  1. Security Concerns: A lost or stolen key is a huge security concern as anyone with a key can open all the doors.
  2. Limited Access Control: Everyone with a key has the same level of access. There’s no way to restrict access to specific areas.
  3. Scalability Problems: Adding new locks often requires replacing existing locks to match the key configuration.

Master Key Systems

Master key systems provide a more sophisticated approach to access control. In simple terms, it can be thought of in this way. Imagine you have a big heavy bunch of keys for different doors in your house. A master key system is like having one key that opens most of the doors, but there can also be special keys for certain other rooms. In this scenario you could have a:

Master Key: This key opens all the doors in the home, like a manager key.

Normal Keys: These keys might open just a few doors, like a bedroom or garage, depending on your needs.

Special Locks: Some locks might only be opened by the master key, like a safe or a storage room.


  1. Prevent unauthorised key copying: The big plus about master keys is that they are very secure. Master keys can only be copied by the locksmith who originally designed them. This is useful if you need to give a tradesman a key while you are at work or a neighbour one, while you are on holiday.
  2. Controlled Easy Access for Caregivers: If you have elderly family members or require in-home care, a master key can grant caregivers access to certain areas of your home instead of access to the whole property
  3. Flexible: The system can grow as your needs change. If you add an extension etc. new locks can be easily integrated and specific access levels can be assigned to different keys.


  1. Higher Initial Cost: Master key systems involve more complex lock mechanisms, making them slightly more expensive than keyed alike systems.
  2. Complexity: Designing and managing a master key system requires expertise. It’s crucial to choose a qualified locksmith.
  3. Strict Key Control: Lost or stolen master keys pose a significant security risk. Careful control procedures are essential.

Choosing the Right System

The choice between keyed alike and master key systems depends on your specific needs. A keyed alike system might be sufficient for a small house or storage unit where convenience is the priority. Whereas a master key system is ideal for offices, apartment buildings, or properties requiring different access levels.

Ultimately, a qualified locksmith can assess your needs and recommend the best system for your situation. They can design a master key system that offers optimal security and convenience, or advice on whether a keyed alike system would be a suitable option. By understanding the strengths and weaknesses of each system, you can make an informed decision that meets your specific security and access control requirements.


Hero Locksmith is an affordable Edinburgh locksmith. Please get in touch if you need help with your locks.