Crop Factor Formula
Crop Factor = √(36² + 24²) / √(Width² + Height²)
The crop factor is the ratio of the diagonal of a full-frame sensor (43.27mm) to the diagonal of your sensor. It indicates how much smaller your sensor is compared to full-frame.
Equivalent Focal Length Formula
Equivalent FL = Actual FL × Crop Factor
The equivalent focal length shows what focal length on a full-frame camera would give you the same field of view as your actual focal length on your crop sensor.
Field of View Formula
FOV = 2 × arctan(Sensor Dimension / (2 × Focal Length))
The field of view is the angular extent of the scene captured by the camera. It depends on both the focal length and the sensor dimension in that direction.