So there are two main differences that define all standard keys. Although maybe we should define what we mean by “standard keys” first. Key systems can be broadly categorised into two types:
Restricted key systems are more commonly used in commercial premises and are typically higher security systems and so have additional features that make them harder to pick. They also are often master key systems set up so that different keys access differing doors, with a master key that can access all doors. One significant feature of restricted key systems is that they are a controlled system and only the locksmith who installed the system can cut keys and then only after receiving authorisation from the system owner.
Standard key systems are those that comes pre-installed in any door, padlock, etc. They are generally simple systems and fairly standardised throughout the building industry. They have no restrictions on them, so any locksmith can replicate keys bought in by any customer. Pretty much every home will have a standard key system installed, as will smaller businesses who primarily only lock external doors.
The two differences that define all standard keys are:
The key profile is the shape of the key as you look at it from the tip of the key, as shown in the first photo below. This profile dictates whether the key will fit in the lock or not and while there are numerous different key profiles – two main key profiles make up about 50% of the market.
The cut profile is the depth of the various cuts in the key when looked at from side on, as shown in the second photo below. With standard keys, the cut varies in depth from 0 to 9, with 0 being the shallowest and 9 the deepest. Standard key systems also usually come in a 5 or 6 pin lock, meaning that there will be 5 or 6 cuts in the key, typically the better systems come in 6 pin as the more pins, the better the security. The key below is a 5 pin system (5 cuts) with the first cut a very shallow cut.