Stops of Light Calculator

A stop is the fundamental unit of light in photography: one stop means doubling or halving the light that reaches the sensor. Every exposure setting works in stops, so understanding them ties aperture, shutter speed, and ISO together. This calculator finds the difference in stops between two values of any one setting. Enter an old and new aperture to see how many stops brighter or darker the change makes, or do the same for two shutter speeds or two ISO values. It also converts a number of stops into a light multiplier so you can see that three stops is eight times the light. This helps you balance an exposure when you change one setting and need to compensate with another, read filter strengths, and think clearly about brightness. All the math happens in your browser, so nothing you enter is sent anywhere.