Distance a Motion Sensor Detects

A motion sensor or detector is considered a linchpin in any security system. It will alert you of the presence of an intruder within your home. It uses various technologies, such as PIR and microwave, to detect movement in a targeted area. The Distance a motion sensor detects depends on the type, brand as well as cost.

Once it detects movement, it sends an alert to your security system’s control panel, thus informing you of an intrusion. Understanding the distance a motion sensor detects is essential, as it will inform you of the number of devices you’d need and where to install them for optimum protection against invasion.

Here is what we found out:

Most motion sensors have a limited range of about 50-80 feet. This is the area coverage within which they can detect movement. For this reason, we advise installing “just enough” motion sensors, particularly in places people frequent, such as the hallways, staircases, bedrooms, and living rooms. 

Also, a motion sensor can hardly detect movement when an object walks directly toward it. Therefore, we advise placing it alongside a hallway where a burglar will walk into it.

As you debate the most suitable location for your motion sensor, consider placing it at least ten feet away from bright windows, radiators, and heat vents. 

Such areas or applications are prone to drastic heat changes, affecting the motion sensor. 

The temperature changes often trigger false alarms, causing unnecessary panic and frustration. You wouldn’t want to experience that, would you?

What Are the Three Types of Motion Detectors?

You can hardly talk about security and energy efficiency without including motion sensors. These devices are a household name for burglary or security cameras. 

They are also excellent for saving energy as they remain off for as long as they sense no motion in the targeted vicinity, especially in office buildings or restrooms. 

While there are various motion sensor brands, only three types are most popular in security systems. These include Passive Infrared (PIR),/Microwave, and Dual Tech/Hybrid. Let’s discuss them more!

Passive Infrared Sensors 

Distance a Motion Sensor Detects
A Motion Sensor

You may have encountered a PIR motion sensor in an office or a frequently visited restroom. PIR sensors are small, easily manageable, and affordable. They usually have a white cover.

It senses a body in motion by detecting a temperature change between the background and the body. 

The PIR technology sensors contain pyroelectric elements that detect infrared radiation. Everything, living and non-living, can produce low radiation levels. 

However, the human body produces significant heat, easily detectable by the pyroelectric sensors.

The PIR sensor contains two slots made of unique material. These slots are sensitive to infrared energy. Therefore, if the sensor detects a differential change between the two slots, it causes a pulse. The device registers this pulse as “movement,” hence triggering the alarm.

NOTE: The infrared light emitted from objects and people is invisible to the human eye but detectable by the PIR technology.

The PIR sensor, which uses the Fresnel lenses arrayed to reflect the infrared energy into the sensor, only gets triggered when it detects a rapid heat change in its field of view. 

However, if the changes are dramatically slow, chances are the sensor will not be triggered. This allows for manipulating or tricking the sensor, especially if an object moves slowly. 

This scenario can only happen theoretically. Practically, Lu, it is impossible to determine this threshold on the fly, and defeating a PIR sensor is not as easy as research speculates.

You can also attach your PIR sensor to a silent alarm, floodlights, a siren, or a camera to signal the security system.

Microwave Motion Sensors 

As its name suggests, microwave sensors use continuous microwave radiation to pick a movement. It works similarly to a radar speed gun. 

Microwave sensors send out radio frequencies, thereby measuring the reflection from an object by identifying a change in the frequency shift. This is how the motion detector is 


Some property owners prefer the microwave sensor over the PIR because of its ability to cover a larger area. However, it is more expensive and less affordable than PIR sensors.

Microwave sensors also have a unique feature that enables them to penetrate “see-through walls.” While this gives them an upper hand compared to other sensors in the market, it is also a disadvantage as it makes them more susceptible to false alarms.

Dual Tech Motion Sensors 

From the discussion above, we’ve noted that both PIR and microwave sensors are susceptible to false alarms. However, thanks to technological advancements, dual-tech motion sensors incorporate the working mechanism of a PIR and microwave sensor. This technology blend minimizes the chances of case alarms.

A PIR sensor is subject to false triggers from anything since everything produces the infrared energy it detects. Even a sudden increase in room temperature can trigger the PIR. On the other hand, the microwave sensor can be triggered by something as minute as an object moved by wind. 

The Dual Tech/Hybrid demands that both sensors detect the changes for the sensors to be triggered. This minimizes the chances of a false alarm.

Below are more motion sensor technologies that are less common:

Tomographic Motion Sensors 

They contain multiple nodes that link together to form a mesh network. This type of sensor gets triggered when the link between two nodes is broken. The link will break upon picking the presence of a person or an object.

Vibration Motion Sensors 

Their functioning mechanism involves detecting vibration caused by humans moving within a room. You can buy them or improvise them at home.

A homemade vibration sensor works through a small mass on a lever that activates the alarm switch when it vibrates. While it can work just as efficiently as the purchased one, you don’t want to rely on a homemade vibration sensor for your security.

Area Reflective Sensors 

Area reflective sensors produce rays from an LED. They then use the reflection from these rays to measure the distance to an object or person. This is how it can tell when a subject moves within a targeted vicinity.

Ultrasonic Motion Sensors

Like the microwave sensor, ultrasonic sensors also measure the reflections from objects in motion through ultrasonic wave pulses.

Contact Sensors (Door/Window)

Contact sensors commonly used on doors or windows contain a magnet to identify movement within a door or a window. It contains two parts: the sensor and the corresponding magnet. When these two parts move apart as the window or door opens, the sensor triggers the alarm, thus signaling the security system. 

Contact sensors are generally used to detect movement on a door or window. 

Video Motion Sensors 

Most security cameras feature advanced signal processing, allowing them to start recording once they sense motion. 

If you value memory storage, you should use a motion sensor-controlled camera. Such cameras do not record unnecessary footage, thus saving you tonnes of memory storage!

Doubtlessly, there is quite a variety to choose from when considering investing in a motion sensor. As you contemplate settling for one that suits your needs, also consider the following tips when dealing with motion sensors:

  1. Prowlers and burglars like to use entry points in a property to break in, such as windows or doors. Consider installing sensors in such areas. There are also sensor types uniquely designed for doors and windows.
  2. Install your sensors in high-traffic areas like the hallway, stairwell, or other people-frequented locations. This will make it easier to bust an intruder. 

You also want to install the sensors in rooms where you store valuable items like money or jewelry. Criminals are mainly likely to target such places.

  1. Avoid installing PIR sensors near heat sources. They function by detecting temperature changes in a given environment. Avoid placing them near a vent, furnace, or fireplace. Any fluctuations in temperature within a targeted area can trigger a false alarm.
  2. Be careful not to block your sensor while installing it. An obstructed sensor won’t function as efficiently as it is supposed to. For instance, a parked car may obstruct a motion sensor installed in a driveway, which may not be noticeable at first. Check and ensure the surrounding area is clear before installing a motion sensor.

After the installation process, dust or debris may accumulate on your sensor. Ensure you carefully wipe it to avoid an obstructed lens. Also, wipe them periodically after the installation.

Let’s learn more about how a motion sensor operates.

How Do Motion Sensors Work?

We’ve learned about the several types of motion sensors available on the market. As their name suggests, motion sensors are uniquely designed to detect movement in a demarcated zone. 

Different motion sensors operate using different technologies. The most common motion sensor technologies are passive infrared and microwave sensors.

Described below is the working mechanism of a passive infrared motion sensor.

Infrared sensors collect infrared light to function. Infrared light is a part of the electromagnetic spectrum, undetectable by the human eye. 

A PIR sensor consists of two separate sensors containing a unique material sensitive to infrared light. You’ll find these two sensors at the back of a lens in a hermetically sealed metal casing. The sealing shields the sensor from damaging external elements like noise, temperature, and humidity.

One of the two sensors reads the temperature in the environment the detector is monitoring. This sensor registers a memory of how the space looks in normal conditions. 

On the other hand, the second sensor detects abrupt changes in temperature in the room. These two sensors will create pulses that signal “movement” once they note any difference from the norm.

Following this working mechanism, PIR sensors can only detect movement and temperature changes so rapidly that they create a difference between what the two sensors are accustomed to seeing.

PIR motion detectors contain lenses divided into segments. The segments are flexible enough to work in a given area and ignore others. This is why you can adjust your detector’s settings, ignoring selected motions or motions in selected areas.

With such configurations, your PIR sensor will alert you of an intrusion from an invader but will ignore it if your pet strolls into your living room. This is an excellent addition to pet-friendly security systems. Don’t we love technology?

Microwave Sensors 

This type of detector reads a space and detects movement using microwaves. It regularly sends microwaves that hit objects and bounce back to the sensor.

As a result, the sensor measures the reflection rate for the objects, which enables it to determine the distance between the sensor and the object. Any movement from the object alters the reflection rate, which registers as motion.

Dual Sensors 

Dual sensors use PIR and microwave technology. Its sensors work in harmony. They verify each other, and if both detect movement, it triggers. The verification helps in minimizing false alarms.

How Much Area Does a Motion Sensor Cover?

The type of motion sensor and the location where you mount it usually determines the area it can cover. The general policy is that the higher the mounting height, the greater the coverage area diameter. 

However, we advise against mounting your sensor unreasonably high as it will limit movement detection beneath it.

A standard motion sensor is designed to look outward. A 360° motion sensor functions similarly to a passive infrared one. However, the 360° ones look forward; no wonder people prefer mounting them on the ceiling to detect movement below it. This also explains why 360° motion sensors are often called ceiling-mount motion sensors.

The higher a ceiling-mount motion sensor is raised, the greater its detection area. We recommend mounting your ceiling motion sensor from about 8 to 12 feet, depending on your height.

Typical motion sensors have a coverage range of up to 80 feet. This means you’d need multiple motion sensors to cover a long hallway or an open workspace. 

To know how much coverage a motion sensor can give, please consider hiring a security company to install it. They will help review your home layout, determining the perfect location for your motion sensor.

A wireless motion sensor mounted on the ceiling can cover an area of up to 14 meters (46 feet) with a 360° field of view. A long wireless motion sensor can cover approximately 100 meters or 330ft indoors. It also covers a 2km (6600ft) line-of-sight.

Since most motion sensors use passive infrared technology, let’s understand their specific area coverage.

An indoor passive infrared sensor has a detection distance range of about 25cm to 20m. An indoor curtain type will also achieve the same coverage. 

An outdoor passive infrared motion sensor’s detection distance is estimated to be between 10-150 meters. 

Generally, outdoor motion sensor lights have a detection range of between 20-100 feet. The detection angle usually calls within 180 degrees horizontally, and you can also adjust some models. Besides, with the advanced technology, you can also configure the distance covered to suit your liking.

Where Should You Not Place a Motion Sensor?

The location of your motion sensor is crucial as it determines its ability to work effectively. Failure to correctly place your device will expose you and your family to insecurity. 

We recommend placing them in areas like the bedroom, behind your valuable items, all entry places, and high-traffic areas.

Walking through your home and placing the sensors in high-traffic areas has been a long-standing thumb rule. This is because burglars will likely walk through these areas as they look to steal your valuables. Below are some of the Don’t’s concerning motion sensor placements:

  • Please do not place a motion sensor where it is directly exposed to sunlight.

Depending on the location of your house, rays of sunlight may penetrate your home through the window. 

Since some sensor technologies are meant to detect infrared light, the sunshine rays might confuse the sensor. This will cause it to sound false alarms, causing unnecessary panic and frustration.

Also, installing your motion sensor in such a location may encourage the intruder to walk directly toward the sensor, which will prevent the sensor from detecting it.

  • Don’t Place Your Motion Sensor Near Heat Sources in the House.

Every household has at least one or more heat sources. These could be a hot air vent, kerosene heater, radiator, furnace, steam bathroom, or portable heat source. Such applications usually produce heat, causing a temperature change. 

PIR sensors are designed precisely to detect a temperature change within a room. If this happens, your sensor is bound to trigger the alarm constantly. This will lead to a series of false alarms that will affect you and the device’s sensitivity.

Listed below are some of the Do’s encouraged for installing a motion sensor:

  • Do Place Your Motion Sensor in a Corner.

Corners are excellent locations for the motion sensor as it helps it achieve more expansive coverage. When placed in a corner, the sensor is more likely to notice the side-to-side motion, which is good at detecting. Also, one is less likely to notice it at the corner. A criminal will come in suspiciously, thereby getting caught.

  • Do Cover the Main Bedroom.

Burglars primarily target the main bedroom as most homeowners store their jewelry, money, or other valuables there. Install a motion sensor here, saving you from potentially unimaginable losses.

  • Do Protect Your Valuables.

You could have more valuable goods not stored in the main bedroom. It could be a TV or a large electronic consumer. Cover them by placing a motion sensor behind them. This way, the sensor will trigger the alarm when a burger attempts to interfere with them.

  • Don’t Forget the Second Floor.

While most burglars comfortably break into a house through the front door or other entries on the first floor, please never estimate the potential of such people who reap where they didn’t show. 

Some can go to the extremes of avoiding the first-floor alarm and using an upper floor. Adequately cover the second floor, just like the first one.

  • Do Cover the Basement.

As we said, don’t underestimate a burglar’s potential; they will go to all extremes to enter your home. Therefore, don’t neglect covering the basement. Place the motion sensor where it will cover the entire staircase.

What Is the Range of An Outdoor Motion Sensor?

Outdoor motion sensors are an affordable yet effective way of deterring intruders. They offer a line of sight on potential intruders without insanely affecting the electricity bill. Outdoor motion sensors will also light jo hour walkways, stairs, or entryways that pose a security risk once the day darkens.

The range of an outdoor motion sensor describes the distance between an object or movement and the sensor that’s triggered. 

Typically, most outdoor motion sensor ranges are estimated between 20 to 100 feet. This distance will vary from one motion sensor to another as you can configure it in the settings.

Further, the detection angle is also estimated to fall within 180 degrees horizontally. Like range, you can customize a sensor’s angle to suit your security needs.

What Is the Difference Between a Motion Detector and a Presence?

Motion Sensors: Detecting Walking Movements. A motion sensor and a presence detector come from a similar family device, only that technical evolution made them develop separately. They have a subtle difference explained below:

Motion sensors’ function entails detecting motion in a targeted area and responding to them accordingly. 

The lights will turn on once it detects movement and notes that the ambient levels are below the predetermined thresholds. These lights will then go off after a set period.

Motion sensors are more affordable than other detectors due to their low price and low sensitivity. This also makes it more available in abundance than other types of sensors.

Presence Detectors: Detecting Tiniest Movements.

Presence detectors use a remarkably high resolution and precision sensor technology to respond to the tiniest movements. Their sensitivity is the main difference between a motion sensor and a presence detector. 

While a motion sensor will detect the movement of an arm, a presence detector will sense a movement as minute as a finger moving.

Presence sensors are used in areas that require high fidelity and minimum movements, like an office or classroom.

Unlike motion sensors with a limited range, presence detectors will cover a broader range and can easily be mounted on high ceilings. 

A presence detector’s ability to detect the smallest movements is called an “occupancy sensor.”

The motion and presence detectors have one feature in common: the ability to save energy.

The two sensors are energy efficient not just in lighting but also in other applications. The “on and off” switch does not rely on human interaction. 

Its automation program allows the light to switch on when the room is occupied and moving. These sensors will save you the worry and frustration of forgotten lights.

What Is the Difference Between a Proximity Sensor and a Motion Sensor?

Over time, different sensors have been embedded in everyday human life. The difference between a proximity sensor and a motion sensor is based on the working principle, the circuit structure, advantages, disadvantages, and their application.

Most motion sensors usually detect infrared energy. Therefore, an IR sensor will measure the infrared radiation, which is invisible to the human eye, to detect movement. While motion sensors detect objects to complete a physical contact, proximity sensors don’t. 

Proximity sensors detect an object’s presence without any physical contact. They detect objects present within the sensor’s detection range and boundary.

How Do I Know If My Motion Sensor Has a Hidden Camera

Motion sensors provide us with the security we all badly need. They can be smartly connected to work simultaneously with other security applications in your home, including hidden cameras. 

While this is an excellent way of beefing up your security, some people do not like being camera-recorded without their knowledge as they consider it a violation of privacy. 

This is why you must know if a motion sensor contains a hidden camera. There are seven ways to determine this:

  1. Inspect the room for any strange-looking or unusual objects.
  2. A motion sensor light will turn on when you approach its vicinity. Some are modified with light switches which you can switch on and off. Turn off the motion sensor light and use your flash to spot hidden cameras. Use the flashlight to scan any reflective lenses in the room that could signify a hidden camera.
  3. Use a mobile phone camera. Your phone will help you identify an infrared camera. This method is the most useful as it does not require a dedicated device. Point your phone camera around the room and look out for any bright red dots that will appear on the screen. 

These dots usually indicate the presence of infrared light. Most cameras emit infrared light to enhance images in dark surroundings.

  1. Check for keyholes, holes, or unusual objects. These are the everyday things used to conceal a camera without drawing attention. Feel for these lenses on the door, walls, and objects. We advise also using your fingers to verify that your eyes cannot see.
  2. You can also use a professional camera detector or sensor.
  3. Check the back of the mirrors. Some motion sensors are used for decorative purposes so that they can be placed in a flower vessel or even a mirror.
  4. You can also use a radio frequency detector and move it around the house to locate any recording device. This type of sensor will make a beeping sound anytime you point at anything that emits radio frequencies. Some motion sensors emit this

Some motion sensors with video recording features start recording as soon as the sensor is triggered. These cameras will only record an event once they detect a change in motion.

Final Thoughts

When considering a motion sensor investment, we also want to know how far it can detect as this will inform the decision on the number of detectors you need in an environment.

The Distance a Motion Sensor Detects

Most motion sensors are determined to have a limited range of about 50-80 feet.

This article has informed us about motion sensors and their comparison to other sensors. It has also discussed the types of motion sensors available on the market today and how they function. 

Have we addressed all your concerns? Good luck installing motion sensors to guard your property and loved ones.

Leave a Comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.