Motion Detector or Window Sensor?

Technology has done the security system some well-deserved justice. It has made various security inventions available on the market; you’d sometimes get torn about what to choose. And today, should you have a motion detector or window sensor?

It can be challenging to determine what product or device will best suit your needs when investing in a home security system. 

When comparing or choosing between a Motion Detector and a Window Sensor, one common feature is that they alert you of trespassers in and around your property.

Read on to find out more! 

What Is a Motion Detector?

Motion Detector or Window Sensor?
A Motion Sensor In Action

Motion sensors use different technologies to detect or measure movement.

However, most motion sensors are specially designed to use infrared technology to identify body movement or heat in a demarcated area.

 Once it detects movement, an alarm or smartphone notification will alert you. Motion sensors have some unique features; let’s look at them! 

Motion detectors monitor and measure movement in large spaces.

The space could be an entire room. This is usually the device’s most popular selling point, which means you don’t need several devices for a spacious room. 

Also, the fewer the devices, the more manageable the installation process is. Motion sensors require no electrical wires. You can easily mount them on the wall or ceiling using screws and brackets. 

Additionally, since motion sensors are lightweight, you will not need to worry about damaging your walls or finding a stud. 

Installing a motion sensor is affordable and pocket-friendly, as a single device is enough for a whole room.

On the other hand, a motion sensor’s ability to monitor a wider area is also disadvantageous. When placed in a large area, they become more susceptible to false alarms. 

For instance, it will trigger when you wake up in the middle of the night for a snack or when your pets wander around in the wee hours. Luckily enough, this is an easily solvable problem. 

All you’ll need to do is to adjust the location and settings, and voila! You will have no more false alarms.

The following are the advantages of installing a motion sensor in your home:

  • Motion sensors detect movement or heat within a targeted area using different technologies. They capture Prowlers or intruders within or outside your home. Therefore, they will trigger your security system’s alarm when an intruder approaches the guarded area.
  • You can wire your motion sensors into nearly any property you want to protect. Motion sensors are available in wired and wireless options, so you can choose one that fits your needs.
  • Active motion sensors can be used in harsh environments with irregular heat cycles. 
  • Motion sensors are durable. The active-type motion sensors have a lifespan of approximately 100,000 hours. 
  • Motion sensors are convenient. They are not limited to the time of the day as they can detect motion in dark, light, indoor, or outdoor conditions.
  • Installing motion sensors, especially wireless ones, is easy. You don’t need an electrician to do the work.
  • Some motion sensors use radio frequency (RF), which can harm humans. According to some scientific studies, when humans are exposed to very high RF intensities, their biological tissues are damaged, and the body temperature rises. The following are the disadvantages/cons  of using a motion sensor: 
  • Some motion sensors’ ability to function is affected by temperature. For instance, those who use PIR technology cannot work in temperatures above 350C.
  • Also, passive sensor types are limited to working only in their line of sight (LOS). This means that they cannot work in non-line-of-sight regions.
  • Motion sensors that use PIR technology are more prone to false alarms. This is because they are wired to detect heat from objects. Almost everything, living and non-living, can emit heat, so any moving object can trigger the PIR sensor.

Before we look into window sensors, look at the listed benefits below that will encourage you to install a motion sensor.

  • It improves your home security.

Most criminals will target a house for criminal activities when the owners are away or asleep. A movement sensor, floodlights, door lighting, or other outside lighting will help deter potential criminals. 

Such lighting is meant to activate mechanically anytime anyone comes too near to your private home.

  1. Enhanced Safety

If you thought humans were the only creatures you may want protection from, then you thought wrong! Flora and fauna can pose a security risk to you, your relatives, and your pets. 

Wild animals, such as raccoons, coyotes, mountain lions, and bears, can also wander to your property in search of food, putting you in danger. 

However, please don’t hold your breath as motion sensor lighting fixtures solve such issues as they scare the animals away.

Also, if you live in areas that experience bloodless winters, motion sensors will be handy! The lights will turn on as soon as you approach the outdoors. 

This will help you easily navigate icy and snowy surfaces, thus reducing the risks of possible injuries.

  1. Energy Saving

If you still use the traditional lighting, you will want them to stay on all night and day for optimum protection, especially if you are away. 

While this provides security, you will soon realize that installing motion sensors could save you energy. 

The sensors greatly help minimize energy consumption in your home or business premises! With them, you will not need to maintain your lighting 24/7.

  1. Cost-Effective

A movement sensor eliminates the need to keep your porch or driveway light on unnecessarily. Instead, it will only turn on once it picks movement or heat, thus reducing the amount of power used. 

You’ll be happy to see your invoice at the end of the month! A motion sensor offers you protection and comfort and reduces power consumption, thus keeping your electricity bill payments at an all-time low.

Although they use different working mechanisms, motion, and window sensors are crucial security necessities for your home. Let’s explore the window sensors and how they operate.

Window Sensors

Motion Detector or Window Sensor?
Image of Window Sensor

Most home/property owners often forget to guard their windows as they assume burglars mostly break in through the front door and ground floors. 

However, windows are the most accessible place for a prowler to trespass. Therefore, they are the best place to tighten security; that’s why you need window sensors! 

Window sensors are simple magnet mechanisms that alert you if one of your windows is suspiciously opened. You will find most home security systems equipped with window and door sensors.

This type of sensor comprises two parts that form a circuit: a magnet and an alarm transmitter. Therefore, a window opening will cause the magnetic contact between the two sections (the alarm transmitter and the magnet) to separate. 

This will, in turn, trip the electrical circuit, thus sending a signal to your alarm keypad or home security app. This is how a window sensor informs you that someone has opened the window.

The following are some advantages/pros of a window sensor that will encourage you to install them on your property:

  • Keep out criminals

Security is increasingly becoming a fundamental need for everyone. A window or door sensor looks out for this need for you and your loved ones. 

The device will alert you through your security system anytime anyone triggers the sensor.

The service of this window sensor is more appealing if your home security system contains a monitoring feature. 

This feature will notify the service providers should anything trigger the sensor. This is a great way to beef up your security, as the service providers can contact authorities and even check up on you by phone to ensure you are safe. Isn’t this such a good deal?

  • Window Sensors Help Ensure Your Loved Ones Stay Necessarily Indoors

While most people will install window sensors to ensure burglars don’t break into their homes, you could also use them to ensure your loved ones stay in. 

The window sensor will inform you on their behalf anytime they want to act slick and sneak out. You could have a teenager who enjoys exploring outside without informing you. 

You could also house your aged parents or relatives who want to leave home without communicating. 

A window sensor is an excellent way to stay on top of things and ensure the people you care for are safe! 

  • Extra Deterrent

If there is one thing a prowler or a criminal hates, it is attention; that’s why they like sneaking in when no one is paying attention. 

Window sensors serve them with what they hate most. If you have an active security system, the window sensors will trigger a loud alarm when anyone forces their way through the window.

This loud alarm will scare away potential criminals who don’t want to attract attention. Also, it will notify you and your family that you are in danger and someone is attempting to break in. 

This will help you take the necessary security precautions on time!

  • Peace of Mind

We all know how the risk of insecurity can trigger anxiety and frustration. A window sensor offers you peace of mind. 

With it, you stay assured that you’ve done everything possible to protect your loved ones, property, and yourself from potential criminals. The sensors can be used in all possible entry points, including the doors!

While we enjoy the above-suggested benefits of installing a window sensor, consider the following pros/Disadvantages.

  • Window sensors are designed to detect when a door or window is being opened. While this is commendable since these are criminals’ most common entry points, others could be slick enough not to use the window or door. If this happens, the window sensor will not protect nor alert you in case of an intrusion. 
  • Like motion detectors, window sensors are susceptible to false positives, especially when they experience loud sounds. Constant false alarms can also cause unnecessary panic, havoc, and frustration! This can reduce its sensitivity and effectiveness, thus putting you at risk. 

Now that we know all the benefits and disadvantages of window sensors, it will also help to understand their anatomy and how they work. Let’s look into it!

Window Sensor Anatomy

You’ll mostly find wireless window sensors that operate on long-lasting batteries. We described earlier that they contain two parts: the alarm transmitter and the magnet. 

Window sensors are structured to communicate with control panels through these transmitters. You’d enjoy using the wireless window sensors as they are easy to install and can be done as a DIY project.

If you want otherwise, don’t feel left out. Wired window sensors are still available and professionally installed. 

The manufacturing company will install them by connecting wires within your walls and running them back to the main alarm control panel.

One common denominator of most modern companies is that they produce sleek and inconspicuous window sensors. A window sensor is a versatile product, available in various sizes and looks. 

Check out what’s available in the market; you’ll be impressed by how many designs you’ll find for your different aesthetic ideas.

The following are helpful tips to consider when scouting for a window/door sensor:


A window sensor is one of the most affordable investments I’m your alarm system components. Most window sensor prices range between $15-$35 apiece. 

A $25 should be enough to get you by. The estimated cost is unlikely to interfere with your overall security bill.


These devices are available in a variety of sizes and styles. Some are sleek and inconspicuous, some are a bit bulky, and some are branded with a company logo. 

Consider a window sensor appearance that would suit your aesthetic needs. 

Smart Phone Controls

We are in the 21st century, where almost everything is digital! Therefore, a security plan with smartphone controls may be appealing to you. 

Such security plants will allow you to monitor your window sensors remotely, regardless of your location. I doubt there is anything more convenient than this! 

Smart Home Automation.

A security plan with smart home automation allows you to sync it with other smart home devices. 

For instance, you can adjust your settings so that your smart lights will turn on anytime your windows open. This is an excellent consideration for more armed security.


The location of any security appliance is critical as it determines its effectiveness in guarding your home or other properties.

The ground-floor windows are the most accessible to intruders. Therefore, it’ll make sense to install sensors on your ground-floor windows. 

Also, you only want to use your window sensors for windows that open (Window sensors are designed to detect when a window opens).

We now know the individual benefits of having a window or motion sensor. Some will wonder if you can use only one of the two for security or both! I’ll answer you in the section below.

Do You Need Window Sensors If You Have Motion Detectors?

Motion sensors detect body movement or heat in a targeted zone. This could be a significantly large area. 

However, window sensors only detect movement when a specific entry point, like a window or door, is opened. 

Since both are security essentials, one may be curious whether they need window sensors when they have motion sensors. Here’s the thing:

Our article describes that these security devices have different working mechanisms. This explains why it will help if you install both the window/door and motion sensors for your security setup. Why choose one when you need both?

Using both security devices will optimally protect your property and your loved ones. They will also make it hard for intruders to get around your property.

If you limit yourself to one type of security sensor, other intruders may become familiar with it and soon be able to circumvent it. 

However, combining the door/window and motion sensors leaves no room for intrusion. Besides, if one sensor malfunctions, the other can be a backup plan. 

You can place a door and a window contact on a door frame or window that can be opened. 

 Usually, a magnet is placed on the moving part of the entry frame. This magnet will notify you if anyone opens the structure. 

However, on rare occasions, an intruder may be smart enough to trick the sensor into believing the window/or door is closed despite opening it. 

In such a case, the security system will miss the intruder’s presence, so you won’t be notified unless you have another security method.

On the other hand, most motion detectors are structured to use passive infrared technology (PIR). This technology allows the sensor to depict any changes in infrared energy within a vicinity. 

Unlike a window sensor, an intruder can hardly trick or manipulate this technology, especially when the sensor is working perfectly. 

However, if they(intruders) are skillful enough to avoid detection from the sensor, then the security system will not identify them.

We are picking that one can easily fool one type of motion-sensing device. However, it’s almost impossible that they can trick both the window/door and the motion sensor. 

This is precisely why using both sensors is adequate for your home or business security systems. Besides, don’t we all agree that having a plan B is important? 

Please never doubt the importance of having multiple security plans, as they will save you from any eventualities.

Will a Motion Sensor Work Through a Window?

You may be tempted to install a motion sensor on your window for various reasons. You could hide it from intruders or protect it from damage caused by physical elements. 

Whatever your reasons are, please do not consider installing a motion sensor on a window. Here’s why:

Motion sensors cannot detect movement or heat through a window. Most of them use Passive Infrared technology (PIR) to pick motion. 

However, a glass window will absorb heat from any object in front of it, making it difficult for the motion sensor to detect changes in IR energy through the glass.

You might also be intrigued by the question, “Why should a window block infrared energy or radiation?”

Any energy associated with heat production is generally considered “infrared.” While your sensor detecting these radiations or heat changes is essential for your security, it would feel uncomfortable if your home remained heated throughout. This is why you have glass windows!

The sun is the largest source of heat for humans, and without windows, the sun would penetrate your house, making it sweltering and unbearably hot for most of the day. However, a window will keep the radiation from the sun away from your home.

Please don’t get into a fret state because of this. Modern technology makes it impossible not to have a solution! If you want your motion sensor to work through a window, you can use a few tricks. Read on to find out!

How Do You Sneak Past a Window Sensor?

Most homeowners will integrate security systems into their homes to deter criminals and wild animals and protect their younglings from sneaking in and out. 

However, in some situations, people want to go in and out of their homes without triggering their sensors. 

Since sensors are unique, depending on the brand, there are also unique ways to sneak undetectably. 

Let’s begin with magnet sensors, commonly used on entry points like windows and doors. Here is how you sneak past them:

  1. Identify Your Ideal Escape Route

Most alarm magnet sensors are installed on the doors and windows of a home. If you want to sneak past it, opt for an easily navigable window. You also want to consider the path you’ll use after exit.

The magnet sensors of most alarms are on your home’s windows and doors. Choose a door or window that’s easy to access and escape. For windows, consider your path after you exit.

You can also sneak past the second-story building, although it will be difficult. For safety purposes, consider using extra tools like a ladder. 

Otherwise, we encourage you to use a ground-floor window with a chest height and avoid the second-story one.

  1. Inspect the Alarm Mechanism to Verify if it’s Magnetic

Magnet sensors usually appear like small metal boxes. Some may have exposed magnet pieces that have a dark color. 

You’ll notice the sensor has two parts: one stationary part and another attached to the movable part of your window.

The alarm will activate once the bond between the magnetic and the movable part is broken or interfered with.

Most people prefer mounting their window sensors on the window top, bottom, or one of the sides.

Unfortunately, it would be impossible to bypass some magnetic sensors, as they are often mounted inside the door jamb and the door itself.

  1. Use a Magnet to Bypass the Sensor.

Please exercise caution when using this method. Some sensors are of high quality, and this technique may not work against them. 

However, in some scenarios, you can place a fridge magnet on the sensor to confuse it into imagining the window has remained closed even when opened.

If the sensor is more sophisticated, consider using tools like a screwdriver to detach the movable part of the sensor from the window. 

Once removed, place it on the stationary part to trick it into thinking the window has remained closed.

NOTE: Consider snapping the magnet sensor before detaching any of the parts. The picture will be a reference when you assemble it back together.

You also want to ensure that your fridge magnet won’t fail you. Therefore, apply it first to the sensor and check the security system. If the sensor determines and reads “closed” when you’ve mounted the fridge magnet and opened the window, then you are sure that this trick will work just fine! 

  1. Return the window/door to normal.

You want to ensure your house is fully protected from burglars and that they won’t use your temporary escape route to break in. 

Therefore, re-engage your alarm as soon as you are back. To do this, fully close your window and detach the fridge magnet you used to trick the sensor.

If your magnet was more sophisticated and you had to use a screwdriver to detach the movable part, fasten it back into place, and you’ll be good to go!

If you can’t remember how to reinstall the mechanism, you’ll need the photo you took here. Use it as a reference.

Should I Put Sensors On Every Window?

We advise that you should mount sensors on every window. This is because a window, door, or any other entry area are common points intruders use to break in. 

Therefore, you want to ensure your security is armed by placing the sensors on all doors and windows.

Your home security needs and the types of windows in your home will determine whether or not you need the sensors. However, not every window will require a sensor. 

For instance, there are windows too small for humans to fit in. In such a case, you won’t need a sensor as it is unlikely that an intruder will break in through this window.

However, install a motion sensor if you have a window through which an intruder can easily break. These sensors will alert you anytime the window opens, thus giving you adequate time to react appropriately.

You can also design your window sensors to work simultaneously with your motion sensors so that the alarm will go off once they detect an intruder. 

Ultimately, your individual security needs will guide you in deciding whether or not to put motion sensors in all windows.

Do Window Sensors Work If Glass Is Broken?

While window sensors are fundamental parts of a home security system, they need to be complemented by other security devices. 

This is why, earlier in the article, we encouraged you to install both the window and the motion sensors. 

In some situations, having window sensors alone may not protect you against home invasion. 

For instance, if an intruder breaks your window and enters through this “broken opening,” the magnet sensors on the window will not trigger the alarm system. 

Why? A window sensor is meant to function when the window is opened. If a person breaks the window and uses it as an entry point, it will mean that they will not have to open the window to intrude.

This confirms that a window sensor will not function if the glass is broken. It will also not be triggered if the window remains closed and an intruder uses the broken glass to invade a home.

Motion Detector Vs. Window Sensor

Although a motion detector and a window sensor are both fundamental home security necessities, they differ in several aspects. Below are some of the differences.


A window sensor is typically sold in packs of 3-4 and has adjustable settings, such as turning the chime on, arming, and disarming. 

The alarm on its sensor gets triggered when the window opens, emitting sounds up to 120 decibels. Window sensors require no wiring, mounting, or hardware. 

This feature makes its installation process quite manageable. Also, they don’t thrive in outdoor environments.

Like window sensors, motion sensors also require no wiring, mounting, or hardware, thus having an effortless installation procedure. 

On the contrary, motion detectors thrive in both outdoor and indoor conditions. No wonder they can be used on driveways, hallways, or staircases! You can fit them in any suitable location.


Both types of sensors are made of plastic. They operate using lithium-ion batteries and other metallic electronic components. 

However, the window sensor is also made with magnets, whereas a motion detector is not!


Like every other device, window and motion sensors have limited lifespans. They require replacement every two years, which can be costly. 

Cost Differences

Most manufacturers sell their window sensors in sets of 2-12 units, with the prices ranging between $2-$15 per unit. 

On the other hand, motion sensors are sold in packs of 2-4 units, with prices ranging between $15-$50 per unit.

This tells us that motion sensors are more costly compared to window sensors. This is because they use heat and motion detection technologies that are more complex than the reasonably rudimentary electromagnetic system adopted by the window sensors.

Motion Detector or Window Sensor?

When figuring out your home security device choices, motion and window sensors are the first to appear in a debate. A motion sensor detects motion or heat in a targeted area, while a window sensor detects when a window is opened. 

A window sensor will alert you when a criminal attempts to break in, while a motion sensor will alert you when the criminal is within your home. One expected advantage of both devices is that they will alert you in cases of insecurities.

Both devices are fundamental security essentials that complement each other. Therefore, we encourage you to install both of them for maximum security.

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