Milesight VS340 vs VS121 vs VS321 vs VS330: Which Desk Occupancy Sensor Do I Need?

Short answer: Choose the Milesight VS340 to report whether one desk or seat is occupied, the VS330 for a toilet cubicle or other small enclosed room, the VS321 for battery-powered ceiling coverage of a room with people counting plus temperature, humidity and light, and the VS121 when one sensor has to cover a wide open-plan zone with up to 16 mapped counting regions. The VS340 and VS330 answer “is this one space in use?”; the VS321 and VS121 answer “how many people are in this area?”. Only the VS121 is mains powered.

Which Milesight desk occupancy sensor do I need?

Choose the VS340 if the question is “is this desk in use?” and you are willing to fit one sensor per desk. It mounts with 3M tape or screws, detects within 1 m using PIR at up to 95% recognition, and ships with interchangeable covers that reshape the field from 1 m × 0.9 m for a single desk up to 1.8 m × 1.8 m for a round table. It is the cheapest of the four.

Choose the VS321 if you want room-level occupancy without running power to the ceiling. It installs at 2.4 m to 4 m, covers 6.0 m × 11.0 m at 4 m (4.6 m × 8.7 m optimal), switches between people counting and desk occupancy modes, and also reports temperature, humidity and a bright/dim light status. It needs 50 Lux of illumination to work.

Choose the VS121 if one sensor has to cover a whole open-plan zone. A 190° × 112° field of view gives 6.8 m × 18.8 m at 4 m, with up to 16 mapped counting regions and dwell time, bi-directional counting with U-turn filtering, and recognition up to 98%. It is the most expensive of the four.

Choose the VS330 if the space is a toilet cubicle, shower or changing room where a person may stay still for a long time. It pairs a Time-of-Flight sensor (0.040 m to 3.500 m, ±2 cm, 27° field of view) with an 80° PIR element for a stated detection accuracy over 99%.

One sensor per desk, or one per room?

The VS340 is not a people counter. It reports the occupancy state of the single desk or seat it is aimed at, so a 40-desk floor needs 40 of them. The ceiling units work the other way round: one device watches an area. If you need per-desk truth on a handful of hot desks, the VS340 is simpler; if you need utilisation across a whole zone, one VS121 or VS321 replaces dozens of desk sensors, and you map the detail back in with the VS121’s 16 regional counting areas or the VS321’s desk occupancy mode.

Neither ceiling sensor is a camera in the sense that matters to a facilities policy. The VS121 collects no images, supports up to 8 privacy masks and lists GDPR among its approvals; the VS321 likewise collects no images.

Which of these need mains power?

Only the VS121, which takes 5 V / 3 A over Type-C, draws 9.4 W and runs LoRaWAN Class C. The other three are Class A on replaceable batteries: the VS340 uses one 4000 mAh ER18505 for around 5 years at 100 triggers a day, the VS321 four 2700 mAh ER14505 for around 11.3 years at SF7 on EU868, and the VS330 three 4000 mAh ER18505 for around 4.2 years at SF7. UK deployments use the EU868 band on all four. All four are IP30 and indoor-only, and the VS321 has the narrowest operating range at 0°C to +30°C.

Milesight VS340 / VS341 Desk & Seat Occupancy Sensor – VS340-868M (PIR)

VS340-868M

£43.39 ex VAT (£52.07 inc. VAT)

View the VS340-868M

Milesight VS321 AI Workplace Occupancy Sensor

VS321-868M

£124.20 ex VAT (£149.04 inc. VAT)

Installation height / effective detection range2.4 m ~ 4 m; 6.0 m × 11.0 m effective range at 4 m

View the VS321-868M

Milesight VS121 AI Workplace Occupancy Sensor

VS121

£276.82 – £284.30Price range: £276.82 through £284.30 ex VAT (£332.18 – £341.16 inc. VAT)

Installation height and detection range2.3 m to 4 m; 2.6 × 8.6 m at 2.3 m up to 6.8 × 18.8 m at 4 m

View the VS121

Milesight VS330 Bathroom Occupancy Sensor

VS330-868M

£67.34 ex VAT (£80.81 inc. VAT)

ToF detection range0.040 ~ 3.500 m (± 2 cm accuracy, 27° field of view)

View the VS330-868M