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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SecurityRelated Tools — You may also find these useful
Alarm Zone Planner
Group your alarm sensors into panel zones so you can see where a trigger came from and arm the perimeter at night while you sleep inside. Enter the sensor count and grouping style to size the zones and the panel. A planning aid; label every zone.
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Describe your home in plain language and get an AI security risk assessment — your main vulnerabilities, the likely threats for your context, and a prioritised, layered set of measures. Strictly defensive and indicative; confirm with a professional site survey.
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Plan a layered home-security stack from your home type and threat level — essentials, recommended and advanced tiers, from locks and sensors to alarms, monitoring and perimeter detection. An indicative starting plan; a professional risk assessment tailors it to your actual home.
Home Plan