Exposure Calculator
Find equivalent exposures and the EV of any aperture, shutter and ISO combination.
The exposure triangle
Exposure is controlled by three settings that trade off against one another: aperture, shutter speed and ISO. Aperture also sets depth of field, shutter speed also sets motion blur, and ISO also sets noise - so the same brightness can be reached many ways, each with a different look. This tool works in that triangle.
Equivalent exposures and stops
A stop is a doubling or halving of light. Because the three controls all work in stops, you can swap between them freely: f/8 at 1/125 gives the same brightness as f/4 at 1/500. Enter a base exposure and a new aperture or ISO, and the calculator returns the shutter speed that keeps the brightness identical.
What exposure value (EV) means
Exposure value (EV) is a single number that sums up an aperture-and-shutter combination at a given ISO. Every one-stop change moves the EV by one. It is a handy shorthand for scene brightness - bright sun is around EV 15, a dim interior around EV 5 - and this tool shows the EV of whatever settings you enter.
How this calculation works
Formula: EV = log₂(N² / t) − log₂(ISO / 100)
where:
N= aperture (f-number)t= shutter timeISO= ISO sensitivity
Sources:
FAQ
What is a stop?
A stop is a doubling or halving of light. Opening one stop of aperture, halving the shutter speed, or doubling ISO each change exposure by one stop.
What are equivalent exposures?
Different combinations that give the same brightness - f/8 at 1/125 equals f/4 at 1/500. They expose the same but differ in depth of field and motion blur.
How do aperture, shutter and ISO work together?
They form the exposure triangle: each controls light, and changing one by a stop can be balanced by changing another the opposite way to keep the same brightness.
What is exposure value (EV)?
EV is a single number describing a combination of aperture and shutter speed; every one-stop change moves the EV by one.