Where to Put Motion Sensors: Placement Rules From Manuals

How high should a motion sensor be mounted?

Use your model's figure, not a generic rule. Manufacturers design the detection pattern for a specific height, and a sensor mounted too high or too low sees the floor differently. Published guidance as of October 1, 2026:

Two things stand out. SimpliSafe's own pages disagree slightly: the product page says 6 feet, the install guide says 4 to 6 feet with the setup button facing up. Mount at 6 feet and you satisfy both. Ring's 1st and 2nd generation detectors want different heights (7 feet versus 7 feet 6 inches), so check which one you own before drilling. If your model's page gives no height, check the installation guide or manual before guessing.

Corner mounting is the common thread. Ring says a corner placement covers the whole room and is better at catching side-to-side motion; SimpliSafe says its sensor looks out and down with a 90-degree field of view and sees best from a corner.

Which way should a motion sensor face?

Across the path, not down it. Passive infrared (PIR) sensors, which Ring and Abode both name as their detection method, react best when a warm body crosses their field of view. A person walking straight at the sensor produces less change.

The makers say this directly:

• ADT: mount the sensor where the logical path of an intruder would cut across its view, rather than heading directly toward the device.
• Ring: a corner sensor is more likely to notice the side-to-side motion it is better at detecting, and a sensor facing sunny windows means an intruder would walk directly toward it, which it is not as good at detecting.

In practice, stand where an intruder would enter (a back door, a patio slider) and trace the route to the stairs or the primary bedroom. Put the sensor on the wall where that route crosses in front of it.

Which rooms need a motion sensor?

Ring's placement guide and SimpliSafe's product tips point to the same rooms:

1. Entryways and the area just behind the front door. Ring has an Entryway setting with an entry delay so you can disarm.
2. Hallways that connect bedrooms and living areas, since nearly any route passes through them.
3. Rooms with several access points or many windows. SimpliSafe suggests a motion sensor instead of individual entry sensors for rooms with 3 or more windows.
4. The primary bedroom, which Ring calls a common first target.
5. Basements with outside access. Ring suggests covering the staircase up to the main floor.

Motion sensors pair with entry sensors rather than replacing them: an entry sensor fires the moment a door opens, a motion sensor catches someone who came in another way. Our door and window sensor comparison covers the other half. Glass break sensors are the third option, useful because many households leave motion off at night; Ring arms motion detectors only in Away mode by default. See are glass break sensors worth it.

What placement mistakes cause false alarms?

The makers' don't-lists overlap almost completely:

• Windows and direct sunlight (Ring, ADT). Sunlight changes the heat picture the sensor reads.
• Heaters, radiators, fireplaces, furnaces and air vents (Ring, SimpliSafe, ADT). Sudden temperature changes look like motion.
• Drafty spots near air conditioners or fans (ADT). Excess air movement can trigger it.
• Facing a staircase (Ring).
• Blocked by furniture or curtains (ADT).
• Outdoors, extreme heat or cold, detached garages and sheds (Ring). Indoor detectors belong inside the same building as the base station.

Pets are the biggest source of trouble. Each model's pet setting has a weight limit (60 lb for SimpliSafe Pet Mode, under 50 lb for Ring's newest model, under 85 lb for ADT Blu), and a cat that climbs onto furniture can still enter the field. Our pet-friendly motion sensors guide covers that in detail.

After mounting, walk the room and trigger the sensor deliberately. Ring recommends testing after installation to confirm the location and settings, including for pets. Cameras follow different placement rules; those are in where to place security cameras.