A bitting code is a series of numbers that corresponds exactly how to cut the ridges (cuts) on a key so it will operate a lock. Each number corresponds to a depth on the key blade. Instead of physically copying an existing key, a locksmith can enter the code into a key-cutting machine or key-generation software to create a perfectly matched replacement.
Why Bitting Codes Matter
Accuracy: Bitting codes eliminate the errors that sometimes happen when duplicating a worn or damaged key.
Security: Codes allow locksmiths to produce keys without having to see or borrow the original.
Efficiency: Large facilities—such as apartment complexes, schools, and offices—use codes to keep track of hundreds or even thousands of keys without manually copying each one.
How Bitting Codes Are Structured
Manufacturer’s System: Each lock brand has its own numbering system and depth increments (e.g., depths 0–9 where 0 is the shallowest cut).
Sequence of Cuts: The numbers are listed in the order of cuts along the blade, from bow (the handle) toward the tip.
Example: A Schlage code
998569means:Cut positions: six along the key blade.
Depths: 9, 9, 8, 5, 6, 9 (where 9 is deeper than 5 or 6).
Spacing Guides: Space refers to how close to the tip or bow (handle) of the key. For example, the 1st space on a Schlage key (by manufacturer's specifications) is closest to the bow. The 1st space on a BEST key (by manufacturer's specifications) is closest to the tip.
WARNING: Kwikset keys operate using a different specification than most key manufacturers. On standard keys (i.e., Schlage) the codes usually range from 0-9. Kwikset uses codes 1-6 (sometimes 7, depending on it's use type) and is usually uses wider cuts than other key types.
Understanding MACs
MACs (Maximum Adjacent Cut Specifications) define the deepest difference allowed between two neighboring cuts on a key. Lock manufacturers set a MAC to keep keys strong and prevent broken or bent blades.
Purpose: Prevents a thin “weak point” between two cuts that could snap under torque.
Example: If a manufacturer’s MAC is 7, and one cut is depth 2, the next cut can’t exceed depth 9 (because 9 − 2 = 7). A jump to depth 10 would violate the MAC and produce a fragile key.
In Practice: Locksmiths always check MAC compliance when designing bitting codes or creating master key systems.
By following MACS guidelines, locksmiths ensure that keys are both functional and durable.