Field of View Calculator

Angle of view = 2 × arctan(sensor size ÷ (2 × focal length)). Use the sensor's width for the horizontal angle, its height for the vertical and its diagonal for the diagonal. A 50 mm lens on a 36 × 24 mm full-frame sensor sees 39.6° across, 27° up and down and 46.8° corner to corner.

Angle of view is the angle in degrees; field of view often means the width of the scene you can see at a given distance. The calculator gives both: at 10 m, a 50 mm lens on full frame covers 7.2 m × 4.8 m (distance × sensor size ÷ focal length).

A smaller sensor sees a narrower slice of the same lens's image. Crop factor is the full-frame diagonal (43.27 mm) divided by the sensor's diagonal, and multiplying the focal length by it gives the full-frame equivalent. A 35 mm lens on a 23.5 × 15.7 mm APS-C sensor (crop 1.53) frames like 54 mm on full frame; 25 mm on Micro Four Thirds (crop 2.00) like 50 mm.

Pick your camera's format from the list. Sizes vary slightly between models, so for exact work choose "Other" and type the width and height from your camera's specifications (usually in the sensor or image sensor section). Phone cameras usually list a 35 mm equivalent focal length instead; use that with Full frame.

Slightly. The formula assumes the lens is focused far away. When you focus close, the lens moves away from the sensor and the view narrows a little (lens breathing); at macro distances the difference is large. Fisheye lenses don't follow this formula at all.