About the Camera Field of View Calculator
Field of view (FOV) is the angular extent of a scene that a camera's lens and sensor capture together. It depends on two things only: the lens's focal length and the physical size of the sensor recording the image. This calculator uses the standard pinhole-camera formula to convert focal length and sensor dimensions into horizontal, vertical, and diagonal angles of view, and it converts those angles into a real-world frame size at whatever distance you specify.
The formula
For a sensor dimension S (width, height, or diagonal, in millimeters) and focal length f (in millimeters), the field of view in degrees is:
FOV = 2 × arctan(S ÷ (2 × f)) × (180 ÷ π)
This comes directly from the geometry of a lens forming an image: the sensor half-width forms one leg of a right triangle, the focal length forms the other, and the half-angle of view is the arctangent of their ratio. Apply the formula three times — once with sensor width for horizontal FOV, once with sensor height for vertical FOV, and once with the sensor diagonal (√(width² + height²)) for diagonal FOV.
Frame size at a distance
Because tan(FOV ÷ 2) = S ÷ (2f) by definition, the width of the scene a camera frames at distance D simplifies to coverage = D × S ÷ f — no trigonometry needed once you know the sensor size and focal length. This calculator applies that shortcut to both sensor width and height to report the full frame size captured at your chosen distance.
How to get accurate results
- Use the sensor's physical dimensions in millimeters, not its resolution in megapixels or pixel count.
- Use the lens's actual (not "35mm-equivalent") focal length together with the sensor's actual physical size — mixing an equivalent focal length with a physical sensor size will double-count the crop factor.
- Keep the distance and the resulting frame size in the same unit (this calculator uses meters for both).
Practical context
This formula assumes a rectilinear lens with no significant distortion, which is a good approximation for most standard photographic and machine-vision lenses but not for fisheye lenses, which use a different projection and produce a wider apparent FOV than this formula predicts. Also note that focal length alone does not determine FOV — the same lens produces a narrower field of view on a smaller sensor, which is why smartphone and crop-sensor cameras often quote a "35mm-equivalent" focal length for comparison.