Milesight WS202 vs WS203 vs VS370: PIR vs mmWave occupancy sensors

Short answer: The WS202 and WS203 are PIR motion sensors; the VS370 pairs PIR with 24 GHz millimetre-wave radar and is the only one of the three whose datasheet quotes a slight-movement detection distance – 4.8 m, alongside 7.5 m for ordinary movement. That single line is the whole PIR vs mmWave decision. The WS202 adds a bright/dark light status; the WS203 adds temperature and humidity.

Which of these three should go in my room?

Choose the WS202 if the room empties and refills and you are driving lights. It has the longest PIR reach of the three, up to 8 m across 120 degrees horizontal by 100 degrees vertical, and reports a bright/dark status against a threshold you set anywhere in the 1-60,000 lux window. It is the cheapest and the smallest, at 50 x 50 x 23.8 mm.

Choose the WS203 if “is anyone in there” is only half the question and you also need the conditions. Same 120 x 100 degree PIR pattern but 6 m rather than 8 m, plus temperature (-20 to 60 degrees C, typically +/-0.2 degrees C over 0-60) and humidity (0-100% RH, typically +/-2%). It is the only one of the three that stores readings on board, 1,000 entries with data retransmission, for rooms at the edge of gateway coverage.

Choose the VS370 if people in the room sit still: desks, meeting rooms, waiting areas. Its 24 GHz radar covers 150 degrees and is specified to 7.5 m for movement and 4.8 m for slight movement, with a quoted recognition rate up to 99%, and a PIR element (110 degrees, within 7 m) alongside it. It costs roughly twice the WS202, and its operating window is 0-30 degrees C.

PIR vs mmWave: does a PIR sensor see someone sitting still?

A PIR element responds to infrared moving across its field, so it is a motion detector being used as an occupancy detector. Milesight’s own figures show where the line falls: the WS202 and WS203 each publish one detection distance, 8 m and 6 m, and no figure at all for slight movement, while the VS370 publishes two, because the radar covers the second case. If your space empties and refills – corridors, WCs, stores, classrooms – PIR is enough. If people sit and read, type or listen, a PIR-only sensor will keep declaring the room empty.

Two things the VS370 is not. It is not a camera and not a people counter: the radar returns presence and a bright/dim light status, never an image and never a headcount. And neither the WS202 nor the VS370 is a light meter – both report a bright/dark state against a threshold, not a lux reading you can log.

Where can each one physically go?

All three are rated IP30, so all three are dry indoor devices; none is specified for outdoor or washdown use. The VS370 narrows further, rated 0-30 degrees C against -20 to 60 degrees C for the WS202 and WS203, so it belongs in heated occupied space rather than a loading bay. On the network, the PIR vs mmWave choice changes nothing: EU868 for the UK, LoRaWAN Class A with OTAA or ABP, NFC setup from a phone, and Milesight D2D on all three to trigger another device directly.

The battery figures are not like for like – around 4.2 years for the WS202, 10.7 for the WS203 and 6.7 for the VS370, all at SF7 on EU868, but each is quoted at a different daily trigger count (30, 64 and 50). Read them as three separate claims, not a ranking.

Milesight WS202 PIR & Light Sensor

WS202-868M

£32.92 ex VAT (£39.50 inc. VAT)

PIR detection distanceMaximum 8 m, over a 120° horizontal / 100° vertical detection area

View the WS202-868M

Milesight WS203 Motion & TH Sensor

WS203-868M

£38.90 ex VAT (£46.68 inc. VAT)

PIR Detection DistanceMaximum 6 m (120° horizontal, 100° vertical)

View the WS203-868M

Milesight VS370 Radar Human Presence Sensor

VS370-868M

£74.82 ex VAT (£89.78 inc. VAT)

Radar detection distanceMovement 7.5 m, slight movement 4.8 m, across a 150° detection angle

View the VS370-868M