hurray your mega menu works

What is a Master Key System and How Does it Work?

Despite being so small, keys play an integral part in the overall security of your property. They allow access into buildings and help secure areas from unauthorised access, making proper key management critical to support smooth day-to-day operations.

Although an increasing number of property owners are now switching to electronic access control systems, many still rely on traditional keys for managing access.

The car keys, the front and back door keys, spare keys, and keys to your security safes and lockboxes can all be a bit challenging to keep safe but you try your best to manage. Now imagine doing the same for big residential and commercial properties.

For big businesses, factories, warehouses, and huge apartment complexes with lots of doors, it can often be extremely difficult to juggle different keys for every door on the property, and it might not always be the most practical.

For that reason, it is recommended to switch to a master key system that lets you ensure access permission according to the level of authorisation, all the while maintaining a high level of security for your property.

Read on to find out what a master key system is, how it works, the advantages of having one, and how Calder Security can help you achieve your security goals:


A master key, in the simplest terms, refers to a key that allows you to access more than one door or lock within a building.

Usually, master keys are only given to certain individuals, such as the property managers, so that they can open all the doors, while lower-level individuals, such as employees and residents, may have sub-master keys that allow them to open only a single door, or limited doors, depending on their level of authorisation.

The purpose of a master key is to simplify the key needs of individuals with high-level access within a property or organisation.

Without a master key, property managers need to carry multiple keys for different doors, which is not only extremely inefficient and burdensome but can also result in security breaches if the keys are lost.

A master key allows them to carry a single key and retain access throughout the property and its multiple doors.


In simple words, a master key system is a security system that uses a multi-tiered framework to grant individuals different levels of access within an organisation.

It consists of the master keys, locks, users, and the complete hierarchy that makes up key management for master key holders.

While a single master key can grant high-level access to an individual user, it is the master key system that determines how securely the master keys are being used in the entire organisation and at different levels of master key access.


A master key typically refers to a key that can access multiple doors and access points within a building, the capabilities of which have changed to include varying levels of master key access.

These access levels allow organisations with several access points to provide individuals with only the access that they need according to their designation within the organisation while limiting unauthorised access.

For instance, for businesses with several employees and access points, managing each location separately may be a hassle, and using a master key may become necessary to avoid having to manage dozens of keys throughout the property.

By designating different levels of master key access, you can maintain a higher level of security and manage access in a much better capacity.

Most master key systems will have between two and five levels of access that can be fully customised, allowing you complete control over your property’s security access control.

The most commonly used designations within a master key system include:

Great grand master key

The great grand master key (GGMK) is the highest-level access for a master key system that can open all the access levels beneath it. It allows access to the entire organisation, including all the doors, locations, and facilities.

GGMKs should be given to only certain people within the organisation who require complete access as it will limit the number of individuals with high-level access and make your master key system as secure as can be.

Grand master key

The grand master key (GMK) is a tier down from the GGMK in the master key access level. It has a higher level of access than master keys but they cannot open all the doors that a great grand master key can.

GMKs are often used for multi-site locations and, similar to GGMKs, they should also be limited to just a handful of individuals within the organisation.

Master key

A master key (MK) can open all access levels beneath it but cannot open locks that the great grand master and grand master keys can.

MKs are usually designated to individuals who require a high level of access within their area, such as district, area, or regional managers, who can access all the areas within their facility but not those areas outside of their access level.

User key

A user key also called a change key, is another name for the regular keys that allow you to open a single lock, like the front door or your office door.

They are given to individuals who do not need high-level access since they are at the lowest level of master key access and cannot open any other doors.


At the most basic level, you need to know that a master key system allows you to open two or more locks using the same key, and to make this work, pin tumbler locks are often used.

Pin tumbler locks consist of a driver pin and a key pin, both of which are lifted so that they rest on the opposite side of the shear line when the right key is inserted. A key must have the right set of grooves in it to lift the key pins to the required height.

If you wish to convert a standard pin tumbler to accommodate a master key system, you will need to add a master wafer in between the driver pin and key pin.

Master keys are related to one another in a hierarchy which is clearly depicted in your master key system schematic that refers to the diagram or blueprint that allows you to visualise the access levels and key security across the property.

The master key system schematic is used to establish your master key system and to mathematically cut keys. It also allows you to determine how the master key system will be organised, how many master keys are required, and who will be selected as master key holders before the keys are cut.


Depending on the size and nature of the organisation, key management can be complex and may include hundreds and thousands of keys.

To ensure effective key management, there are a few important aspects that need to be considered in order to keep track of all the keys required to access different areas of the property. They include:

  • Hardware keying design
  • Access permission policies
  • Key tracking
  • Key storage

Hardware keying design is the first step in designing an effective key management system and is directly related to the structure of the facility.

It involves determining the various entry points that will require keyed locks and creating a security hierarchy that includes each access point.

The hardware keying design corresponds to the access permission within the organisation and requires you to determine which entry points will allow access to the general public, limited users, or require high-security access control, which is something an experienced professional locksmith can help you with.

The access permission policies refer to the second part of setting up an effective key management system and apply to the key holders and users within the system.

For this, you will need to outline the different categories of residents, employees, staff, visitors, and other users in the system who will require access through the various access points within the organisation.

Along with the access permissions, it is also necessary to assign access restrictions to the users since they determine the type of users that won’t be permitted to access high-security areas.

The third part refers to key tracking that allows the property owners to keep a record of all the key’s access permissions along with the person responsible for them.

All keys, including all keys in a master key system, must be stamped with unique serial numbers and assigned to a particular access level.

This record-keeping allows you to keep track of who the keys are given to, who approved the access permissions, and the dates of issuance and return.

The last part is proper key storage which refers to providing a secure place to keep the keys, their duplicates, as well as their backup copies.

There are different types of storage cabinets depending on the number of keys included in the system, all of which make it possible to locate the keys, identify if any are missing, and track who is responsible for each one.

Many property owners are now turning to electronic key management systems, which are cabinets made of steel and require a code or proximity access card to unlock them.

In addition to providing safe key storage, they also keep a digital record of key issuances and users and automatic notifications when the keys are not returned on time.


Master key systems not only help manage keys but also maximise security by controlling access and providing added control and flexibility.

Here are all the reasons why having a master key system is a good idea for your property, especially if you have multiple access points and users with varying access permissions:

Key management

Managing keys can be a huge hassle, especially since they are often lost, stolen, or misplaced, forcing you to go through the process of replacing them or rekeying the locks, both of which can be time-consuming and expensive.

Master key systems offer an easy solution for this problem by designating different levels of access based on the user’s role in the organisation, particularly for commercial and industrial properties with multi-level access.

In addition to simplifying things and making the keys easy to manage, master key systems also help prevent unauthorised access into the building as well as internal theft.

Access control

Security is a top priority for all types of properties, and with the right security measures in place, you can have peace of mind knowing that only authorised individuals will be granted access into the building and all kinds of unauthorised entry will be prevented.

Master key systems offer complete control over all the areas of your property so that you can limit access as much as is needed. You also won’t have to worry about unauthorised key duplication since master keys prevent this from happening.

Affordable security

One of the best ways to keep your property safe is to secure the access points within it, and what better way than by implementing a master key system?

Master keys are both affordable and easy to use and allow you to control who has access to your property, making them an attractive option for residential, commercial, and industrial properties.

They also allow added flexibility with how you want only certain people in specific parts of the building and eliminate the need for multiple locks on each door.

Ideal for multi-tenant buildings

Managing multi-tenant buildings such as apartment complexes can be difficult, considering the number of keys and the different tenants who all need access.

The best way to manage this is by implementing a master key system into your property, which won’t only limit access but also allow complete control over who has access to which access point in the building.

It is a perfect solution for property managers and allows them to keep a single key for several doors in the building and keep records of key issuances and usage.

A great solution for big businesses

Since there are several employees in a business, all with varying levels of hierarchical access, it can often be extremely difficult to manage who has access to where and who doesn’t, which can often lead to security breaches.

With a master key system, you can solve this problem by granting access to the employees based on their access permissions and designation within the organisation.

This way, you can know who has access to which areas of the business, which can be particularly useful in the event of a security breach or emergency, and you can also limit lower-level employees from accessing areas they don’t need access to.

While master key systems offer great advantages in the form of controlled access and better key management, many property owners are now moving to electronic access control systems that completely eliminate the need for physical keys along with the risk of them being lost or stolen.

Instead of relying on physical keys, you may opt for modern authorisation methods such as digital codes, proximity cards and fobs, and biometric identification.


Calder Security has been in the security industry since 1976 and we are members of the Master Locksmith Association (MLA).

We provide all kinds of security solutions designed bespoke to your property’s requirements and are experts in both master key systems as well as electronic and keyless access control systems.

Our expert team of SSAIB approved installers can help you assess your security needs and offer the right master key system or different types of access control systems including intercom, proximity fob, card swipe, keypad, and biometric systems that work with fingerprints or retina scans.

We are experienced with creating sophisticated access control systems for residential properties, large scale commercial enterprises, as well as smaller businesses.

We offer expert key cutting services from our Lock and Safe Shop in Wakefield where you can get your keys cut while you wait. We can cut virtually any key to a high degree of accuracy without having to send them away to be cut using our state-of-the-art digital equipment and key cutting machinery.

We can also work on a wide range of locking mechanisms, are specialists in wooden, UPVC, and aluminium doors, and the official suppliers for leading lock brands including Chubb, Yale, Securikey, and Garrison.

Contact us here or call us on 0800 612 9799 to talk to our professional locksmiths right away!

Photo by Florian Berger on Unsplash