Camera Field of View Calculator

Camera field of view describes how much of a scene a camera records through a particular lens. It is expressed as an angle, usually in degrees. A wide angle includes more of the scene, while a narrow angle isolates a smaller area. Because a rectangular image has two dimensions, photographers commonly compare horizontal, vertical, and diagonal field of view. The diagonal value is often used when comparing lenses, but horizontal and vertical values are especially useful for framing, panoramas, surveillance coverage, and computer vision. This calculator uses the rectilinear lens formula: angle equals two times the arctangent of the sensor dimension divided by twice the focal length. Sensor width produces the horizontal angle, sensor height produces the vertical angle, and the sensor diagonal produces the diagonal angle. All measurements must use the same unit. Camera specifications normally provide both sensor dimensions and focal length in millimeters, so millimeters are used here. The result assumes a lens focused near infinity and a rectilinear projection without significant distortion. A shorter focal length produces a wider view on the same sensor. A larger sensor also produces a wider view with the same focal length. This relationship explains crop factor: a 35 mm lens on an APS-C camera frames more tightly than the same lens on a full-frame camera. The lens itself has not changed, but the smaller sensor captures a smaller portion of its image circle. Real photographs can differ slightly from the calculated angle. Focus breathing changes effective focal length at close distances, manufacturers round focal-length markings, and fisheye lenses use a different projection. Digital stabilization or in-camera correction may crop the image as well. Use the result as a reliable planning value, then confirm critical framing with the actual camera and lens. For security cameras, architecture, filmmaking, and panorama work, this quick calculation makes lens selection and coverage comparisons much easier.