This Aperture area calculator helps you compute the aperture area of a lens. Try the calculator right now or keep on reading to learn about the aperture diameter, f-number, and the aperture area equation. Features: - Instant calculation - Result are copy able to other app - Formula are include as reference - Support up to 16 decimal place - Support various unit for each input Aperture is a hole or an opening through which light travels. The aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The f-number (sometimes called focal ratio, f-ratio, f-stop, or relative aperture) of an optical system is the ratio of the lens’s focal length to the diameter of the entrance pupil. The focal length of an optical system is a measure of how strongly the system converges or diverges light. The amount of light captured by a lens is proportional to the area of the aperture.