What is a BS3621 Locks British Standard Lock?

by | Dec 19, 2020

The security of a lock should be any homeowners primary concern, after all some locks are extremely easy to get into. There are many types of locks however insurance providers often stipulate the need for BS3621 locks due to the rigorous testing of the wear and tear of the lock and the testing of durability against the most common methods and tactics of burglars to compromise the lock.

What is BS3621?

BS3621 is a lock standard by the BSI (British Standards Institute) for tamper resistant, thief resistant and durable locks. British Standard Approved locks are usually found on external front or back doors in the home. To the untrained eye, if you see that you have a BS3621 lock you know that you have a decent security standard. Most insurance companies will require you have these locks fitted to your door.

About BS3621 British Standard Locks

BS3621 was first introduced in the 1960’s and covers “locks operated by key from both the inside and outside of the door”, here are some key facts about BS3621 locks:

  • Commonly found on wooden or timber doors in residential properties.
  • Key operated – meaning the key is used to unlock and lock the door.
  • Current Standard Version is BS3621:2017
  • Identifiable by the kite symbol and standard number on the inside of the lock
British Standard Lock Kite


The main advantages of having a BS3621 British Standard approved lock is:

  • Heavily tested against common burglary techniques like lock drilling and lock picking
  • Insurance approved – BS3621 locks adhere to most major insurance policy requirements
  • Provide added security and safety

What is a Insurance Approved Lock?

Some insurers require locks that meet a suitable standard, generally this standard is BS3621. Often kite marked locks are also referred to as Insurance Approved Locks, this means that some insurers require this standard of lock fitted to your external doors.

It is important to remember the approval body is the British Standards Institute themselves.

What type of locks are approved to British Standard 3621?

There are many types of lock that conform to British Standard 3621 (BS3621)

Common locks that conform to BS3621:

  • Mortice Sash Lock
  • Mortice Dead Lock
  • Euro Sash Lock
  • Euro Dead Lock
  • Night Latches
  • Rim Locks

Mortice Locks have to have 5 levers to conform to BS3621 Standard (5-lever mortice lock). It’s important to remember not all 5-lever Mortice locks conform, for free advice call one of our locksmiths in Bangor who can advice you further.

What do BS3621 locks look like?

What is the British Standard Kitemark?

The Kitemark, is a UK specific product and service quality trade mark. The Kitemark is owned and used by the British Standard Institution.

Kitemark logo

The Kitemark is most commonly found on products where safety is paramount. You can find the Kitemark on security locks, man hole coverings, helmets and fire extinguishers.

Requirements for BS3621 Locks

For a lock to comply with British Standard BS3621 it must have:

  • 5 Levers including + 1000 key differs
  • Anti-Drilling Qualities (usually with a hard plate)
  • Anti-Picking Qualities (top half pin stack ridged, indented or mushroom shaped)

British Standard Versions

British Standard has moved through many different versions. While the Kitemark is important, the later the version the more rigorous the testing has been. The latest version of British Standard Lock is 2017, see the full list of British Standard lock versions below:

  • BS 3621:2017
  • BS 3621:2007
  • BS 3621:1998.
  • BS 3621:1980.
  • BS 3621:1963

Summary of BS3621 British Standard Locks

To check if your locks comply to British Standard look out for:

  1. British Standard Kitemark engraved into the lock
  2. Lock Standard Number engraved into the lock

Remember if it’s a Motice lock, only 5-lever Mortice locks comply (but not all).

If you are looking to upgrade your locks you should call a qualified locksmith to assess and recommend the best lock.
Prices: Prices can vary dependant on the lock itself, see our locksmith pricing Ireland & UK guide.

Written By Paul

A local locksmith in Belfast with a love for the city (Belfast is a great place to live), history & food. When I'm not changing locks, you will find me writing about them.

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