People Counters


Density is a People Counting Sensor

About: Density uses depth data, machine learning, and computer vision to anonymously count people.

Industry: Corporate offices. Companies in the Fortune 1000. The system is designed to measure how people use a company’s offices, conference rooms, and other work areas.


No hardware cost, anonymous data, designed for corporate offices, real-time API. More info —


No identity tracking; Powered device (not battery operated)

Data type:

Depth data and infrared lasers.


$495 unit

$41 per month

Cameras and/or Optical Sensors


Most cameras see in flat color images. Smart cameras use second-by-second changes in pixel color to determine movement and identify people or other objects in a scene.


Retail, building security, corporate offices.


Inexpensive, impressive analytics

  • Cost: Cameras are relatively inexpensive and they come in a wide variety of form factors.
  • Analytics: Cameras on the cutting edge have impressive on-board computer vision. They can generate a ton of information about the areas they’re deployed in. People tracking, facial recognition (i.e. Face++), object detection, etc. As it’s become more practical to make use of machine and deep learning, camera systems have become impressive.


“Handoff problem,” privacy, culture, and security

  • The Handoff Problem: When pointing multiple cameras into a room, you have to overlap their fields of view. If you don’t, or if you’re using multiple cameras, they have to intelligently make sense of the people that disappear in-between the FOVs. This is called the handoff problem and it takes some processing.
  • Lack of privacy is a camera’s biggest limitation. Some smart cameras will “anonymize data locally,” meaning they will blur or obscure a person’s face or downsample the image’s resolution so it looks fuzzy. It’s a good method but can be difficult
  • Culture: In an office setting, it can be difficult to get beyond the pilot stage with camera solutions for counting people. Often, employees push back as a system looks to scale.
  • Security: For buyers with a robust infosec posture, camera systems are an ideal target for hacking. Even benign systems that obscure a video stream locally can be compromised and made to do otherwise.

Data type: RGB video or flat images.

Average Cost

Variable based on the device’s intelligence and the analytics system behind it. Companies usually charge a hardware fee and an analytics or dashboard fee.

Active Infrared or Break-beam

How it works

Break beam sensors have an infrared emitter and an infrared receiver. The sensors are typically placed on one side of a doorway (or both sides). The tech looks like this:

Standard AIRs count the number of times infrared light is “broken” or passed through and at the end of the day, the user (you) divides the number by 2 to determine the total number of people that came and went. It’s pretty analog.

More intelligent AIRs claim to do bidirectional movement.


None, really. They’re battery operated but they’re inaccurate. Not good for counting people.


Not accurate

  • Blindness: Break beam sensors are inaccurate. The sensor becomes blind when two people enter at the same time (side-by-side) or enter and exit at the same time.
  • Human movement is complex: Break beam sensors rely on signal processing to sort out when a person has entered. The signal is hard to make sense of when lines form or people bring boxes and bags with them.

Data type:

Signal and signal processing algorithm

Average Cost



How it works

Thermal uses body heat and computer vision to determine objects.




Unreliable accuracy.

Thermal systems rely on motion to distinguish humans. It has difficulty when people stand still, when they overlap, and when they carry warm things (like laptops).

Average Cost

The most popular thermal people counter is about $1,500 / device. Price varies by vendor. The underlying technology is not terribly expensive (10s-100s of $$ off the shelf).


How it works

Ultrasonic sensors bounce inaudible sound off people as they walk by. Each one has an emitter and a receiver.


Low power


Accuracy. Put simply, if someone wears a fuzzy coat, ultrasonic devices get confused because the sound waves bounce inconsistently. If you’re trying to count people, there are better technologies… unless everyone is wearing denim. It does very well with denim.

Average Cost

They are low cost. Ballpark $50–$100 (max).