Two phrases come up constantly when a business sorts out its keys: master key and keyed alike. They sound similar, they both reduce the jangling bunch of keys, and they are often confused — but they solve different problems, and choosing the wrong one means either too little control or needless cost. This guide is a straight comparison: what each does, where each fits, and how to decide which your business actually needs.
This guide is the decision. For how the systems are built — pinning, hierarchies, restricted keys — see our deeper guide to master key systems explained.
A keyed-alike set is the simpler idea: several locks are all cut to the same key, so one key opens all of them. There is no hierarchy — every door in the set is equal, and the one key opens every one of them. It is the “I just want to carry one key” solution.
Where it fits: a small shop where the front, back and stockroom doors can all share a key; a single office suite; a set of doors that the same people all need to reach anyway. It is cheap, simple and convenient. Its limit is also its nature — because every key is the same, you cannot give one person access to some doors but not others. Everyone with the key opens everything.
A master-key system introduces a hierarchy. Each door has its own individual key (a “change key”) that opens only that door, while a single master key opens all of them. So a member of staff carries a key to just their area, the cleaner carries a key to just the rooms they clean, and the manager carries one master that opens the lot.
Where it fits: any business with zones and different access needs — offices with departments, a building with shared and private areas, a property with multiple tenants. The whole point is selective access: people reach what they need and nothing more.
Keyed alike = one key opens several doors, everyone equal. Master key = each person opens only their own door(s), one master opens all. Choose by whether you need different people to have different access.
It comes down to one question: does everyone need the same access, or different access?
Many businesses end up with a blend: a master-key system overall, with keyed-alike sub-groups inside it (for example, all the stockroom doors keyed alike under the master). A good locksmith designs the hierarchy around how your business actually runs.
For larger premises, the hierarchy can go deeper. A grand master system adds sub-master levels — a department head’s key opens their floor, a building manager’s key opens the building, and a grand master sits above everything. The same logic, more layers. It scales from a handful of doors to a whole estate without losing the principle: each key opens exactly its remit.
Whichever you choose, the system is only as secure as your control over the keys. If the keys are ordinary blanks, anyone can copy them at a kiosk — and an uncontrolled copy of a master key compromises every door it opens. For any business system, use restricted or patented keys that can only be cut under your authorisation, and keep a register of who holds what. Our guide to restricted and patented key systems explains why.
One practical advantage of a well-designed system: when a member of staff leaves or a key goes missing, you re-key only the affected cylinders rather than the whole building. With a master system you can re-pin the relevant doors and reissue; with keyed-alike you re-key the set. Either way it is a contained job, not a full replacement.
A named, vetted master locksmith covers your area — no call-out fee.
Getting the choice and the hierarchy right is a design job before it is a fitting job — and it pays off for years. Every LocksmithLocal locksmith can assess how your business works, recommend keyed-alike, master or a blend, and supply it with proper restricted-key control. See our commercial locksmith services, or find your local locksmith to talk it through.
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