Intrusion Sensor Quantity Calculator
Good defence is layered — catch an intruder at the skin of the building with perimeter contacts, then again inside with motion sensors. Enter your doors, accessible windows, rooms and key points to size the total sensor count and the panel/zone size to plan for. Planning figures; runs in your browser.
Perimeter first: a contact on every external door and reachable window detects entry at the boundary. Motion sensors are the second catch inside. Wireless zones expand via expanders; hardwired zones map one-to-one.
- Door contacts3
- Window contacts8
- Motion (PIR) sensors5
- Key-point devices2
Planning estimate only — verify against the product datasheet and a site walk-through: sensor ranges, room geometry and blind spots decide the real count, and you should walk-test every sensor after install. Life-safety and alarm-monitoring decisions rest with your installer and alarm-receiving centre, not this tool.
Turn the count into a system
Related Guides — Deep-dive reading
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