Master Key System Calculator
Key bitting calculation for master and sub-master groups.
Inputs
Results
Total key combinations
1,000,000
MACS-compliant combos168,070
Available change keys42,016
Keys per group (max)10,504
Incidental keys (risk)96
Capacity used (%)0.1%
System feasible (1/0)1
Estimated cost$1,046.00
How to Use This Calculator
- Enter the number of individual doors (changes) in the system.
- Set the number of master key levels needed (grandmaster, master, sub-master).
- Input the number of key holders at each level.
- Review the minimum key blank series and cylinder count required.
- Select a restricted keyway to prevent unauthorized key duplication.
How the result changes with Pin positions
| Pin positions | Total key combinations |
|---|---|
| 4.3 | 10,000 |
| 5.05 | 100,000 |
| 5.95 | 1,000,000 |
| 6.7 | 10,000,000 |
What each input means
- Pin positions
- Number of pin chambers in the lock cylinder (typically 5 or 6).
- Depths per pin
- Number of available cut depths (e.g., Schlage = 10, Kwikset = 7).
- MACS
- Maximum Adjacent Cut Specification — max depth difference between neighboring pins.
- Master levels
- Hierarchy depth: 1 = master+change, 2 = grand master, 3 = great-grand master, 4 = max.
- Sub-master groups
- Number of sub-master groups (e.g., departments, floors, or zones).
- Keys per group
- Number of individual change keys needed in each sub-master group.
What each result means
- Total key combinations
- Theoretical maximum key bittings (depths^pins) before constraints.
- MACS-compliant combos
- Usable combinations after applying MACS constraint to adjacent pins.
- Available change keys
- Total unique change keys the system can support across all groups.
- Keys per group (max)
- Maximum unique change keys available per sub-master group.
- Incidental keys (risk)
- Estimated number of cross-keys that could unintentionally open other locks.
- Capacity used (%)
- Percentage of system capacity consumed by requested keys (keep under 100%).
- System feasible (1/0)
- 1 if the system can accommodate all requested keys, 0 if over capacity.
- Estimated cost
- Approximate cost including system design fee and per-lock keying charge.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersPin positions = 6, Depths per pin = 10, MACS = 4, Master levels = 2 = 6 input(s) provided
- Calculate Total key combinationsTotal key combinations1000000 = 1000000
- Calculate MACS-compliant combosMACS-compliant combos168070 = 168070
- Calculate Available change keysAvailable change keys42016 = 42016
Related Calculators
The questions that sit next to this one — chosen by subject, including calculators filed under a different category.
More in Home, Garden & Maintenance.