Find the f-number after N stops and the light reaching the sensor.
Opening one stop multiplies light by two, which lowers the f-number by a factor of the square root of two while the physical diameter grows. Aperture controls both exposure stops and depth of field, so knowing exactly where a new f-number lands keeps both in check.
Aperture Clarity
Diameter = focal length / f-number; one stop down = sqrt(2) in f-number
Diameter = focal length / f-number; one stop down = sqrt(2) in f-number Opening one stop multiplies light by two, which lowers the f-number by a factor of the square root of two while the physical diameter grows.
Aperture controls both exposure stops and depth of field, so knowing exactly where a new f-number lands keeps both in check.
This calculator takes 3 inputs: Focal length, Aperture (f/), More light. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.