SimpliSafe Entry Sensor Review

The SimpliSafe Entry Sensor is not flashy, and that is exactly the point. It is the workhorse component you add to a SimpliSafe Gen 3 system to make sure every door that opens gets noticed. If a starter kit is the foundation of your security setup, entry sensors are the bricks you keep adding until every entry and egress door is covered.

The role in your system

Cameras show you what happened. Entry sensors tell you the instant a boundary changes. When a door or window opens, the two-piece magnetic sensor separates and the system knows immediately. That certainty is the backbone of a real alarm setup: there is no guessing whether a shadow was a person or whether motion was the cat. A door either opened or it did not.

This is why entry sensors are usually the first thing to buy after a base kit. They are inexpensive relative to cameras, they install in minutes, and they directly secure the highest-risk part of any home: the doors people actually use to get in and out. For entry and egress doors specifically, this sensor is the right tool for the job.

How many you need

Most people will need at least one or two of these beyond whatever a starter kit includes. Begin by listing every entry and egress door: the front door, the back or patio door, and the door from the garage into the house. That garage-to-house door is the one homeowners forget most often, and it deserves a sensor just as much as the front door does.

Once your doors are covered, the same sensor handles vulnerable windows: ground-floor windows, basement windows, windows hidden from the street, and any window reachable from a porch roof or low extension. You do not need to sensor every second-story window on day one, but plan to expand opening by opening until the easy access points are all protected. Because the sensor is sold individually, it is simple to scale coverage at your own pace.

Install and placement

Installation is genuinely fast. The sensor uses peel-and-stick adhesive, so most doors and windows take only a few minutes: place the larger sensor body on the frame, align the smaller magnet on the moving door or sash, and confirm the gap is within range. Included screws are there if you want a permanent mount or if a surface does not hold adhesive well.

Placement is where you get reliability. Keep the two pieces close and aligned when the door or window is closed, mount on clean surfaces, and avoid textured or dusty trim where adhesive can fail. On tricky surfaces, clean first and consider the screws. A sensor that falls off in a month is worse than no sensor because it creates false confidence, so it is worth taking an extra minute per opening to mount it well.

Chimes and Secret Alerts

Day to day, the most useful feature is the instant chime from the Base Station, paired with sensor-specific voice announcements. Once each sensor is named, you do not just hear that something opened, you hear which door. That turns the system into ambient awareness even when it is not armed: you know when the back door opens while you are in another room.

Secret Alerts are the clever extra. They send a phone notification when a chosen sensor opens without sounding the alarm. That is ideal for quietly monitoring a medicine cabinet, a liquor cabinet, a home office, a gun safe area, or a door that kids use to come and go. It lets one sensor pull double duty as both a security device and a discreet awareness tool.

What owners are saying

Owners consistently praise how easy these sensors are to install and add to an existing SimpliSafe system, often noting that setup takes just a few minutes per door or window. The reliable chime and smartphone notifications come up frequently, and many people specifically call out Secret Alerts for keeping tabs on cabinets, garages, or kids without sounding the main alarm.

The critical feedback is narrow and predictable: adhesive strength can be hit or miss on certain surfaces, and the per-sensor cost adds up when outfitting a large home with many openings. Neither issue undercuts the core value. With a high overall rating across thousands of reviews, the consensus is that these sensors are reliable and simple, which is exactly what you want from the most-repeated component in your system.

Editor notes

Day to day, these entry sensors just work. Once they are named and set up, I get clear alerts whenever a door or window opens, so I always know what is happening around the house. The compact form factor makes them easy to place cleanly on frames, and the Secret Alert option is great for doors I want to monitor quietly without triggering a full alarm.

Who it's for

This is an easy recommendation for any SimpliSafe Gen 3 owner who needs to cover more doors and windows, which is nearly everyone building out a system. It is the right pick for entry and egress doors, vulnerable windows, and cabinets you want to monitor quietly. Skip it only if you are not on the Gen 3 platform or if you specifically need a different brand's ecosystem.