Focal Length Calculator

The focal length of a lens determines how strongly it converges or diverges light, directly affecting the magnification and field of view of your imaging system. 

Accurate focal length calculations are essential for selecting the right lens to meet your imaging requirements. Our focal length calculator offers a straightforward, reliable way to determine the ideal lens focal length by entering your sensor size, desired field of view, and working distance, helping you quickly optimize lens and sensor combinations for any application.

Field of view calculations

Input Parameters

Provide your system specifications below. Hover over each input for guidance.

  • Camera Sensor Size: Image sensor format represents the size of the sensor, though it is not literally the size in inches as expressed.
  • Working Distance: Distance from the lens to the target plane. Longer distances require longer focal lengths to maintain the same field of view.
  • Desired Horizontal FOV: The width of the scene you want to capture, in millimeters or meters.
  • Desired Vertical FOV: The height of the scene you want to capture, in millimeters or meters.

Tip: Focal length selection involves balancing field of view, spatial resolution, and working distance. Accurate inputs ensure the best lens choice for your application.

How System Parameters Affect Focal Length

  • Sensor Size: Larger sensors require longer focal lengths for the same field of view.
  • Working Distance: Increasing distance generally requires a longer focal length to maintain scene coverage.
  • Desired FOV: Wider FOVs require shorter focal lengths, narrower FOVs require longer focal lengths.

Understanding these relationships ensures you select a lens that balances coverage, resolution, and working distance.

Enter your parameters below to explore how adjustments in field of view and working distance will change your focal length requirements.

The width of the target
The height of the target
The distance from the target to the focal point of the lens

This value represents the lens focal length required to achieve the desired field of view with your specified sensor and working distance. Use it to select compatible lenses and design optical systems that meet your coverage and resolution requirements.