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PPM / Pixel Density Calculator

PPM / Pixel Density CalculatorDetect/recognize/identify distance. Fast, free and secure — works in your browser. By AK Computer, Dwarka.

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How to use

  1. 1 Enter the camera resolution and the scene width covered.
  2. 2 The tool computes pixels per metre (PPM) on target.
  3. 3 Compare the PPM against detect, recognise, and identify thresholds.
  4. 4 Adjust the lens or distance to reach the required PPM.

Frequently Asked Questions

What is pixel density (PPM) in CCTV?

PPM is pixels per metre on the target. It measures how much detail a camera captures at a given distance, which decides whether you can detect, recognise, or identify a person.

How many PPM do I need to identify a face?

As a rule of thumb, roughly 25 PPM allows detection, about 125 PPM allows recognition, and around 250 PPM or more is needed to identify an unknown person.

Why does my HD camera fail to identify faces far away?

PPM drops as distance grows because the same pixels are spread over a wider scene. Use a longer lens or move the camera closer to raise pixel density on target.