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HFOV / EFL calculator

Horizontal Field Of View (HFOV), instantaneous Field of View (iFOV) and Effective Focal Length (EFL) calculators

The following calculators compute the Horizontal Field of View (HFOV) or Effective Focal Length (EFL) of a camera and lens system, for any sensor format.

Using the EFL calculator, enables system engineers to find a lens according to pre-determined FOV,  which will enable easy search of the relevant product within Ophir’s catalog.

Using the iFOV calculator will enable finding the core parameter in picture resolution and target recognition.

Please note that are an approximation only, as they are based on the paraxial approximation, which does not take lens distortion into account. Errors in wide-FOV lenses could be significant.


Number of horizontal pixels

Pixel pitch



Effective focal length in millimeters