Different Grade Locks and Their Security

If you are not a locksmith and have never dealt with changing locks or upgrading the security of you home then you are probably unaware of the different security grades locks are given. This, however, is important information to have in mind if you want to ensure that your home is well protected or when you are changing your locks. To assist with the process DG Locksmiths created this guide as a most basic information resource on lock grades. As a registered locksmith Glasgow, Edinburgh, Falkirk and Paisley we have an extensive range of products and services tailored to the needs of our customers. These include all grades locks, and we can provide professional advice on which ones are most suitable for you. So what grades locks exist?

Grade 3 Locks

The lowest quality locks are Grade 3 and are certified for use on any kind of doors. They have the lowest acceptable quality of finish, fit and operation and are not pick resistant, fire resistant, or resistant against physical attacks. These are most often used on residential building with low security risks. As a result of the lock quality grade they are the cheapest.

Grade 2 Locks

The Grade 2 locks are testes for double the opening number of the Grade 3 locks. They meet quality standards and undergo tests with one requirement being having some resistance against physical attacks and fire. Their fit, finish, material and operation is better than the ones of Grade 3 locks. They are used on commercial properties and in residential properties in which higher grade security is required by the occupants. They are more expensive than Grade 3 locks as a result of the manufacturing process and the higher security.

Grade 1 Locks

Grade 1 locks have the highest levels of finish, fit and operation. They are tested for double the number of openings of Grade 2 locks. They often have features that make them resistant to manipulation and physical attack. These are more expensive than Grade 2 and Grade 3 locks.


The security provided by the lock, however, does not depend only on the lock grade. It is greatly affected by the level of security of the cylinder used in the lock. These can be split in three categories: low security, medium security and high security cylinders.

Low Security Cylinders

The low security cylinders can be used with any grade locks discussed earlier. This type of cylinders are not pick or drill resistant, and often use wide keyways to allow used convenience during inserting the key. They may have a plug to shell tolerance of between 0.003 and 0.010 to allow smooth operation. As a result they offer low level of security.

Medium Security Cylinders

The medium security cylinders also work with any grade lock. They usually offer pick resistance and tighter plug to shell tolerance of 0.005. The pick resistance can come in the form of mushroom, serrated, or spool pins/wafers/drivers. They have tighter or more complex keyways and could use more than the standard 5 pin/wafer combination.

High Security Cylinders

High security cylinders only work with Grade 2 or Grade 1 locks. They offer high pick resistance, through a range of means. These include non-paracentric keyways, split wafers, stainless steel pins/wafers, sidebars, and use of more resilient materials such as magnets, biaxial configurations, multiple rows of pins/wafers and so on. Through the installation of hardened inserts at strategic places these cylinders offer drill resistance and are considered high security.


Do you need help choosing the right lock?

If you are uncertain as to which lock to choose then DG Locksmith can help. As a registered locksmith Glasgow residents have relied on for years, we can provide quality advice regarding the lock and cylinder you require. We are also a registered locksmith Falkirk and locksmith Paisley. DG Locksmiths also provides services in other cities, being one of the best locksmiths Edinburgh. Our extensive range of services for residential properties and commercial properties has exactly what you are looking for. To learn more about the ways in which we can help you improve your home security contact us today.