How to Calculate CCTV Camera Lens Range

Before you invest in installing CCTV cameras all around your house for security and safety purposes, you should consider calculating the camera lens range. In order to calculate the camera lens range of a CCTV camera, you just need to perform a few basic mathematical calculations. Depending on the purpose for which you are installing a CCTV camera, you can decide the size of the field-of-view. For example, if the camera is being installed to record footage of people who enter a room, you will need a camera with small and focused field-of-view.


  • 1

    Using a tape measure, calculate distance between the CCTV camera and the area that you wish to monitor with the CCTV camera. You may have to take help from a friend for this purpose.

  • 2

    Now you need to measure the width of the area that you will be monitoring with the CCTV camera. For instance, if it is the entrance to your home that you want to view, just measure the width of the entrance door and add a few inches to the final reading.

  • 3

    Calculate ratio between width measurement and the distance between the CCTV camera and the area that you wish to monitor. For example, it you want to monitor a 7 feet wide area which is at a distance of 21 feet from the CCTV camera, the answer to your calculation will be 3.

  • 4

    Depending on the camera sensor size, choose a multiplier from the list given below.

    - 1 inch sensor multiplier               = 12.8
    - 2/3-inch sensor multiplier            = 8.8
    - 1/2-inch sensor multiplier            = 6.4
    - 1/3-inch sensor multiplier            = 4.8

  • 5

    Multiply calculation from Step 3 with the correct value from Step 4. Assuming that the sensor size of you camera is 1 inch, 3 × 12.8 = 38.4. This means that you will need a 38.4mm lens.

  • 6

    To calculate the vertical field-of-view, simply multiply reading from Step 3 (the horizontal field-of-view) with 0.75. This means 3 × 0.75 = 2.25. This is the vertical field-of-view that the CCTV camera will allow.

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