When ordering door locks, cylinders, deadbolts, or commercial hardware, one of the most important decisions is how the locks should be keyed. Terms such as keyed alike, keyed different, master keyed, change key, control key, and keyway describe different parts of the keying system, and confusing them can result in locks that do not operate the way you intended.
The basic difference is straightforward. Keyed alike locks use the same operating key. Keyed different locks use different operating keys. A master keyed system allows individual locks or groups of locks to have their own operating keys while also allowing one or more higher-level keys to operate multiple locks.
This guide explains how each option works, when each is commonly used, and what to verify before ordering residential or commercial door hardware.
Keyed Alike vs. Keyed Different vs. Master Keyed: Quick Answer
Keyed Alike (KA): Two or more compatible locks or cylinders are keyed to the same combination so the same operating key works all of them.
Keyed Different (KD): Locks or cylinders are keyed to different combinations so one lock's operating key normally does not operate the others.
Master Keyed (MK): Individual locks or groups of locks can have their own keys while a master key is designed to operate multiple locks within the system.
The right choice depends on the number of doors, who needs access, how much separation is required between areas, whether the building already has a key system, and how the facility will be managed over time.
What Does Keyed Alike Mean?
Keyed alike means that two or more compatible lock cylinders are prepared so they operate with the same key.
For example, a home might have a front door deadbolt, side door deadbolt, and garage-entry lock that are all keyed alike. Instead of carrying three separate keys, the homeowner can use one key for all three doors.
Keyed-alike arrangements are also used in commercial applications when several doors should provide the same level of access.
Common examples include:
- Several exterior doors used by the same staff
- A group of storage rooms that should share one key
- Multiple rental-property service doors controlled by the same maintenance team
- Several padlocks or cabinet locks assigned to one department
- Residential entry locks that should operate from a single key
Keyed alike does not necessarily mean that every lock in an entire building must use the same key. Locks can be organized into separate keyed-alike groups.
Example of Keyed-Alike Locks
Suppose a small office has four exterior doors.
If all four locks are keyed alike, one operating key can open all four doors.
Employees who receive that key therefore have access to every door within that keyed-alike group.
This is convenient and reduces the number of keys people need to carry, but it also means that access cannot be separated between those four openings unless the keying arrangement is changed.
What Does Keyed Different Mean?
Keyed different means that each lock or cylinder is prepared with a different key combination.
A key that operates one keyed-different cylinder normally does not operate another keyed-different cylinder unless those cylinders are intentionally incorporated into a broader master-key system.
Keyed-different locks are useful when access needs to remain separate.
Examples include:
- Separate offices used by different employees
- Individual storage rooms
- Tenant spaces
- Utility rooms with restricted access
- Separate equipment rooms
- Individual classrooms or departmental spaces
Keyed different provides separation at the individual operating-key level.
Example of Keyed-Different Locks
Imagine four private offices identified as A, B, C, and D.
If the locks are keyed different:
- Key A opens Office A
- Key B opens Office B
- Key C opens Office C
- Key D opens Office D
Each person can receive access only to the door assigned to that key.
This provides more separation than simply keying all four offices alike.
What Is a Master Key System?
A master key system adds another level of access above individual operating keys.
In a basic master-keyed system, individual locks or groups of locks can have separate operating keys while a master key is designed to operate several or all of those locks within the designated system.
The individual operating keys are commonly called change keys.
For example:
- Office A has Change Key A
- Office B has Change Key B
- Office C has Change Key C
- Office D has Change Key D
- A Master Key operates Offices A, B, C, and D
The person using Change Key A cannot normally open Office B, but a person authorized to carry the master key can access both.
What Is a Change Key?
A change key is the normal operating key at the lower level of a master-key system.
It may operate one cylinder or a group of cylinders that are intentionally keyed alike.
For example, a maintenance employee might receive a change key that operates several maintenance closets while another employee receives a different change key for office doors.
The master key is designed to operate those locks at a higher access level.
Master Keying Does Not Mean Every Door Uses the Same Key
This is one of the most common misunderstandings.
If ten locks all use exactly the same normal operating key, they are simply keyed alike.
A true master-key arrangement allows different change-key combinations to exist beneath a higher-level key.
That distinction makes master keying useful when a building needs both individual access control and centralized access.
Keyed Alike vs. Master Keyed
Keyed alike and master keyed are not the same thing.
With keyed-alike locks, the same normal operating key works every cylinder in the keyed-alike group.
With a master-keyed system, several different change keys can operate their assigned cylinders while a master key operates a broader group of those cylinders.
For a small home or office where everyone should have the same access, keyed alike may be all that is needed.
For a facility with departments, offices, classrooms, maintenance spaces, or multiple access levels, master keying may provide a more useful structure.
Keyed Different vs. Master Keyed
Keyed-different cylinders can also be part of a master-key system.
From the perspective of the individual change keys, the locks remain different. Each change key operates only its assigned cylinder or group.
The difference is that the cylinders have also been designed so a higher-level master key can operate them.
Therefore, the terms keyed different and master keyed are not always mutually exclusive.
Can a Master Key System Have Keyed-Alike Groups?
Yes.
A master-key system can include groups of locks that are keyed alike beneath the master.
For example, a school might have:
- Five maintenance rooms keyed alike to one maintenance change key
- Ten administrative offices keyed alike to another departmental key
- Individual classroom keys
- A master key that operates the designated groups within the system
The exact structure depends on the building's access requirements and the capabilities of the selected cylinder and key system.
What Is a Grand Master Key?
Large key systems can contain more than one level of master keying.
A grand master key can operate multiple groups that each have their own master key.
For example, a campus might be divided into several buildings:
- Building A has its own master key
- Building B has its own master key
- Building C has its own master key
- A grand master key operates designated locks across all three buildings
Even larger systems can contain additional hierarchy, but greater complexity requires careful planning and key control.
Who Commonly Uses Master-Key Systems?
Master-key systems are commonly considered for facilities where different people need different levels of access.
Examples include:
- Schools and universities
- Office buildings
- Healthcare facilities
- Hotels and hospitality properties
- Multifamily properties
- Warehouses
- Government buildings
- Retail facilities
- Industrial buildings
- Property-management portfolios
A well-planned system can reduce the number of keys carried by authorized personnel while preserving separation between individual rooms or departments.
What Is a Keyway?
The keyway is the shape or milling configuration inside the cylinder that determines which key blank can physically enter it.
Keyway and keying are different concepts.
Two cylinders may use the same keyway but have completely different key combinations.
Likewise, a master-key system normally requires compatible cylinders and keyways that are designed to operate within the intended system.
When adding locks to an existing building, identifying the current keyway is often just as important as deciding whether the new hardware should be keyed alike or master keyed.
Factory Direct Hardware carries a variety of Commercial Door Cylinders and IC Cores for commercial keying applications.
Does the Lock Brand Matter?
Yes.
Do not assume that locks from different manufacturers can automatically be keyed together simply because their keys appear similar.
Compatibility can depend on:
- Manufacturer
- Cylinder format
- Keyway
- Number of pins
- Existing key system
- Restricted or proprietary keyway requirements
- Interchangeable-core format
- Lock series
If you are matching an existing system, identify the cylinder and keyway before placing the order.
Can Different Types of Locks Be Keyed Alike?
Often, yes, provided the hardware uses compatible cylinders and keyways.
For example, a compatible keyed lever and deadbolt from the same key system may be able to operate from the same key.
Commercial systems can sometimes incorporate cylindrical locks, mortise locks, deadbolts, padlocks, cabinet locks, and other compatible cylinder products into a coordinated key system.
Compatibility must be confirmed for the exact products.
Can Different Brands Be Master Keyed Together?
Sometimes, but never assume that this is possible from the brand names alone.
Some commercial hardware is available with cylinder preparations or keyways designed to coordinate with another manufacturer's system. Other products use manufacturer-specific cylinders or proprietary systems.
If a project must integrate multiple brands, confirm the keyway, cylinder format, and key-system requirements before selecting the hardware.
How Do Interchangeable Cores Fit Into Master Keying?
Interchangeable cores are frequently used with commercial key systems because the removable core can simplify future keying changes.
If a key is lost or access needs to change, an authorized person with the correct control key can remove a compatible interchangeable core and install another properly prepared core without replacing the entire lockset.
This is particularly useful in buildings where personnel or access requirements change frequently.
To understand the difference between small- and full-size interchangeable-core systems, read our Interchangeable Core Locks: SFIC vs. LFIC/FSIC guide.
What Is a Control Key?
A control key is used to remove and install a compatible interchangeable core.
It serves a different purpose from a change key or master key.
A change key operates the lock according to its assigned access level. A master key operates designated cylinders within the key hierarchy. A control key operates the retaining mechanism that allows an interchangeable core to be removed from or installed into its housing.
Control keys should be carefully managed because they provide the ability to exchange compatible cores.
Keyed Alike Does Not Mean Master Keyed
Another common ordering mistake is requesting locks keyed alike when the actual goal is to create different user-access levels.
If every employee receives the same keyed-alike key, everyone with that key has the same access.
If some employees should enter only certain rooms while supervisors or facility managers need broader access, a master-key system may be more appropriate.
Master Keying Does Not Change the Lock Function
Keying determines which keys operate the cylinder. It does not determine how the lock itself functions.
A commercial lever might be:
- Entry or office function
- Classroom function
- Storeroom function
- Passage function
- Privacy function
- Institution function
The internal lock function determines how the inside and outside trim operate.
The cylinder and keying determine which authorized keys can operate the keyed portion of that function.
Compare our Commercial Entry Door Levers, Commercial Classroom Door Levers, and Commercial Storeroom Door Levers when choosing the operating function of a commercial lock.
Keyed Alike for Residential Doors
For many homes, keyed alike provides the simplest solution.
A homeowner may want the front door, garage-entry door, side door, and rear entry to operate from one key.
This reduces the number of keys needed without adding the complexity of a commercial-style master-key hierarchy.
Before ordering, verify that the selected locks use compatible cylinders and keyways.
Keyed Alike for Rental and Property Management
Property managers should consider how access will be separated before keying an entire property alike.
Keying every tenant door alike would obviously eliminate needed separation between units.
Instead, a property may use individual tenant keys, maintenance access, common-area keys, interchangeable cores, or a carefully planned master-key system depending on the building and applicable requirements.
The keying arrangement should reflect who actually needs access to each opening.
Master Keying for Offices
An office building provides a simple example of why master keying can be useful.
Employees may receive keys that operate only their assigned offices. Department managers may need access to several rooms. Facility personnel may require broader access for maintenance.
A properly designed key hierarchy can provide these different access levels without requiring every authorized person to carry a large ring of individual keys.
Master Keying for Schools
Schools often contain classrooms, offices, storage rooms, mechanical spaces, exterior doors, and other openings with different access requirements.
A key system may need to distinguish between teachers, administrators, custodial staff, maintenance personnel, and other authorized users.
Because schools can involve many cylinders and access levels, the key system should be planned before ordering replacement hardware rather than developed one lock at a time.
Master Keying for Commercial Projects
For larger projects, create an access plan before placing the hardware order.
Identify:
- Every keyed opening
- Who needs access to each opening
- Which openings should be keyed alike
- Which openings require unique change keys
- Which people require master-level access
- Whether additional master levels are necessary
- The required keyway
- The cylinder or core format
- Existing key-system information
- How future expansion will be handled
A little planning at the beginning can prevent significant rekeying work later.
What Information Is Needed to Match an Existing Key?
If new locks must operate with an existing key, do not rely solely on the appearance of the key.
Useful information can include:
- Lock manufacturer
- Cylinder manufacturer
- Keyway
- Key code or bitting information when available and appropriate
- Existing master-key system documentation
- Cylinder or interchangeable-core model
- Photographs of the existing key and cylinder markings
- Project or key-system records
See our Door Hardware Key Codes page for additional information on identifying keying requirements.
What If You Do Not Know the Existing Key System?
Do not guess.
Trying to add locks to an established commercial master-key system without identifying the existing system can result in cylinders that physically fit the locks but cannot operate with the required keys.
Start by identifying the manufacturer, cylinder format, keyway, and any available key-system records.
For large or restricted systems, the facility's locksmith or key-system administrator may need to provide the required information.
Restricted and Patented Key Systems
Some commercial key systems use restricted or patented keyways intended to provide additional control over authorized keys and cylinders.
These systems can have ordering restrictions, authorization requirements, or controlled distribution.
If the existing building uses a restricted system, do not order a standard open-keyway cylinder as a substitute simply because it fits the lock.
The cylinder must be coordinated with the building's actual key-control program.
Should Every Building Use a Master Key System?
No.
Master keying is useful when a building genuinely needs multiple access levels.
A small office with two exterior doors used by the same people may be better served by simply keying those locks alike.
A storage property where each customer requires completely separate access may use keyed-different cylinders without a customer-access master.
The goal should be to create the simplest key system that satisfies the actual access requirements.
Key Control Is Part of the System
A key system is only as manageable as the policies surrounding it.
For commercial projects, determine who is authorized to:
- Receive master keys
- Receive change keys
- Receive control keys
- Order duplicate keys
- Order replacement cylinders or cores
- Approve changes to the key hierarchy
- Maintain key-system records
Master keys and control keys should generally be issued more selectively than ordinary change keys because they provide broader capabilities.
Common Keying Mistakes to Avoid
Ordering Everything Keyed Alike Without Considering Access
One key may be convenient, but it also gives every holder of that key access to every lock in the keyed-alike group.
Confusing Keyed Alike With Master Keyed
Keyed alike means the same normal operating key works the locks. Master keyed means different lower-level keys can exist beneath a higher-level master key.
Assuming Keyed Different Cannot Be Master Keyed
Individually keyed cylinders can still be designed under a master-key hierarchy.
Ordering by Lock Brand Alone
Brand does not provide enough information to determine key-system compatibility. Cylinder format and keyway matter.
Ignoring the Existing Keyway
A lock can fit the door correctly and still be incompatible with the building's keys.
Confusing a Control Key With a Master Key
A control key removes or installs interchangeable cores. A master key operates designated lock cylinders within the key hierarchy.
Waiting Until After Installation to Plan the Keying
For multi-door projects, access levels should be planned before cylinders and locks are ordered.
Keying Selection Checklist
Before ordering keyed door hardware, confirm:
- How many keyed openings are involved
- Whether the locks should be keyed alike or keyed different
- Whether a master-key hierarchy is required
- Who needs access to each door
- Lock manufacturer and series
- Cylinder or core format
- Keyway
- Existing master-key information
- Whether interchangeable cores are used
- Whether control keys are required
- Whether the system uses a restricted or patented keyway
- Whether future expansion is expected
- How keys and system records will be controlled
Frequently Asked Questions
What Is the Difference Between Keyed Alike and Keyed Different?
Keyed-alike locks share the same operating-key combination. Keyed-different locks use different combinations so their individual operating keys do not normally operate one another.
What Is the Difference Between Keyed Alike and Master Keyed?
Keyed alike means the same normal key operates every lock in the group. Master keying allows different change keys to operate individual locks or groups while a higher-level master key operates multiple designated locks.
Can Keyed-Different Locks Have a Master Key?
Yes. A master-key system commonly uses different change-key combinations beneath a master key.
Can Two Different Lock Types Use the Same Key?
Potentially, if their cylinders, keyways, and key systems are compatible. Do not assume compatibility without checking the exact products.
Can Different Brands Be Keyed Alike?
Sometimes, when the products support compatible cylinder formats and keyways. Compatibility must be verified before ordering.
Does a Master Key Open Every Lock?
A master key operates the locks assigned beneath that master within the designed key system. In a larger hierarchy, one master may operate only a particular group while a grand master operates multiple groups.
Is a Master Key the Same as a Control Key?
No. A master key operates designated lock cylinders. A control key is used to remove and install compatible interchangeable cores.
Can SFIC Cores Be Master Keyed?
SFIC systems can be incorporated into master-key arrangements when the selected core, keyway, and system are designed for it. For more information, see our SFIC vs. LFIC/FSIC guide.
Should My House Be Master Keyed?
Most homes do not need a master-key hierarchy. Keying compatible exterior locks alike is usually the simpler approach when the goal is to use one key for several doors.
What Is the Best Keying Option for an Office?
It depends on who requires access. A small office where everyone uses the same doors may work well with keyed-alike locks. A larger office with private rooms, departments, storage areas, and facility personnel may benefit from a planned master-key system.
Choosing the Right Keying Arrangement
The best starting point is not the key itself. Start with the access plan.
If every authorized person should open the same doors, keyed alike may provide the simplest solution.
If each opening should have separate access, keyed different may be appropriate.
If different users need individual access while managers, maintenance staff, or facility personnel need broader access, a master-key system may provide the necessary hierarchy.
For commercial projects, also verify the cylinder format, keyway, existing key system, interchangeable-core requirements, and future expansion plans before ordering.
Browse Factory Direct Hardware's Commercial Door Cylinders and IC Cores, Commercial Door Hardware, BEST Access Door Hardware, and Schlage Commercial Door Hardware for compatible lock and cylinder options.
If you are planning a larger project or need coordinated keying, visit our Contractor & Project Quotes page to discuss the hardware and keying requirements before ordering.
For additional terminology, visit the Hardware Glossary, or browse the Factory Direct Hardware Learning Center for more guides covering locks, cylinders, interchangeable cores, door closers, hinges, and commercial door hardware.
Get more Factory Direct Hardware guides in Google Search.