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Shelly Presence Gen4 is an indoor mmWave radar sensor designed to detect people who remain still, including seated occupants, without using a camera. Shelly’s consumer page advertises simultaneous tracking of up to 10 people and 10 customizable zones, while the company’s technical and safety documents specify up to six detected people. That conflict matters if you are planning room automation for a busy space.
What Shelly Presence Gen4 does
Presence Gen4 (model S4SN-0U61X) uses 60–64 GHz millimeter-wave radar rather than optical imaging. Radar can continue to report a person’s presence when they are sitting quietly, an area where ordinary motion sensors may turn lights off after a period of inactivity. Shelly positions the device for automated lighting, heating and cooling, and energy routines.
The sensor is intended for indoor automation, not security, medical supervision or emergency response. Shelly’s safety guide explicitly says, “This device is not a safety system. Do not rely on it for life-critical or emergency applications.”
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How many people can it detect?
The answer depends on which official document you consult. Shelly’s current consumer product page says “Multi-person tracking: Tracks up to 10 people simultaneously” and also advertises up to 10 customizable detection zones. Shelly’s US technical documentation lists object detection as “Yes, up to 6 objects (people),” and the company’s IFA announcement and safety guide likewise state a limit of six people.
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The API exposes a tracking-range setting from 1 to 10 objects. That setting may explain the consumer-page wording, but it does not independently establish that released hardware can reliably identify 10 real people at once. Until Shelly reconciles the documentation, treat six as the supported figure in technical planning and verify the firmware version and regional documentation before relying on a 10-person limit.
| Official material | Claim | How to interpret it |
|---|---|---|
| Consumer product page | Up to 10 people simultaneously; up to 10 zones | Marketing claim for the current product listing |
| US technical documentation | Up to 6 detected people; up to 42 m² coverage | Engineering specification |
| IFA announcement and safety guide | Up to 6 people | Additional official limit stated in company materials |
| API documentation | Tracking range configurable from 1–10 objects | Software setting, not proof of simultaneous real-world accuracy |
Zones and room coverage
You can divide the sensing area into as many as 10 customizable zones. Zones let an automation distinguish, for example, a desk, sofa and doorway instead of treating the entire room as one presence field. The technical documentation specifies coverage of up to 42 m² (about 450 square feet). Actual results depend on mounting position, room geometry, furniture and radar sensitivity, so the rated area should not be treated as a guaranteed usable range in every layout.
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Presence Gen4 also includes a light sensor that reports dark, twilight and bright states. Automations can therefore combine occupancy with ambient light—for example, turning lights on only when a zone is occupied and the room is dark.
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- Wi-Fi 6 for network connectivity
- Bluetooth 5 LE
- Zigbee 3.0
- Matter-over-Wi-Fi
- Documented integration with Shelly Cloud, Home Assistant and other supported platforms
Matter-over-Wi-Fi can make the sensor available to compatible Matter controllers, while Zigbee offers a separate mesh-radio option. Home Assistant users should check the current integration and firmware notes for the features they need, especially multi-zone data and person-count reporting. Connectivity standards do not change the six-versus-ten capacity discrepancy.
Rank #3
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Power, dimensions and installation
| Specification | Official figure |
|---|---|
| Power input | USB-C, 5 V / 1 A |
| Consumption | 2.5 W nominal; 3.5 W maximum |
| Size without stand | 64 × 41 × 26 mm |
| Size with stand | 73 × 41 × 37 mm |
| Operating environment | Indoor; −20 °C to 40 °C; 30–70% relative humidity |
The unit can stand on its base, attach with adhesive tape, or mount with screws and wall plugs. Documentation covers both wall and corner mounting patterns. Position it where furniture and walls do not unnecessarily obstruct the sensing field, then configure sensitivity and zones for the room rather than assuming the default settings are optimal.
Filtering pets and small moving objects
Sensitivity and filtering controls are intended to reduce triggers from small objects, including pets and robot vacuums. Filtering is useful for lighting and HVAC routines, but it is not an accuracy guarantee: the room, mounting angle and object movement still affect results. Test each automation during normal use and adjust thresholds if a pet or appliance repeatedly changes the room state.
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Privacy and practical limits
Because the sensing method is radar rather than a camera, there is no optical image stream described in Shelly’s product and safety materials. That can be preferable in bedrooms, bathrooms or workplaces where cameras are unacceptable. Radar presence is nevertheless a sensor reading, not proof of identity or a substitute for visual verification. It should not be used to decide whether someone needs medical help, whether a building is secure, or whether an emergency has ended.
No independent accuracy percentage or error-rate test is established in the available official material. Buyers should therefore avoid interpreting the person-count claim as a measured guarantee under all room conditions.
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Availability and buying checks
Marketplace coverage is still uneven. A report from T3 described listings in Spain and Germany while noting that wider availability and pricing had not settled. If you look for “Shelly Presence Gen4” on Amazon or another marketplace, confirm the seller, shipping region, firmware or hardware revision, warranty terms and current price at checkout. Do not assume a listing’s “10 people” wording overrides the six-person figure in technical documentation.
Quick Recap
Who should consider it?
- Good fit: rooms where lights or climate controls must stay active while people sit still; households that want camera-free sensing; installations needing Matter, Zigbee or Home Assistant connectivity.
- Plan carefully: large or crowded rooms, projects that require a guaranteed count of 10 people, or layouts exceeding the documented 42 m² area.
- Wrong tool: life-safety, emergency, medical or security applications.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
