Exposure Value (EV) Calculator
Enter aperture, shutter speed and ISO to get the exposure value. Results update as you type.
Inputs
Press Calculate to update results as you change values.
Results
Understanding exposure value
Exposure value is a compact way to describe how much light a combination of aperture and shutter allows, adjusted for ISO. One EV step equals one photographic stop. If two setting combinations share the same EV, they produce the same brightness on the sensor (ignoring reciprocity failure and secondary effects).
This calculator implements the standard definition used in photography education and light-meter design. It is especially useful when you read an EV off a meter or chart and want to explore equivalent aperture–shutter pairs, or when you document a lighting setup for later recreation.
Formula
N = f-number, t = exposure time in seconds, ISO = sensitivity. At ISO 100 the ISO term vanishes.
Example
f/2.8, 1/100 s, ISO 100 → EV ≈ 11.0. Moving to f/4 (one stop less light) at the same shutter and ISO yields EV ≈ 12.0.
FAQ
Is EV the same as the number on my light meter?
Often yes for meters that report EV at ISO 100. Some devices report lux or foot-candles; convert using the meter’s manual. Always confirm whether the meter includes ISO in its readout.
Can EV be negative?
Yes. Very dark scenes or extreme settings (tiny aperture, fast shutter, low ISO) produce negative EV. That simply means little light is being recorded.
Using EV in the field
Many handheld meters can display EV at ISO 100. Read the scene, then explore equivalent combinations here without touching the camera. If the meter says EV 12, you might choose f/8 at 1/125 s ISO 100, or f/4 at 1/500 s, or f/8 at 1/250 s ISO 200—all sharing the same brightness. Street photographers often fix ISO and aperture, then ride shutter; studio shooters fix aperture and ISO, then ride shutter or light power. EV is the common language between those habits.
When comparing two cameras side by side, matching EV ensures the files land at similar brightness before picture profiles or RAW curves diverge. That is useful in multi-cam events and scientific documentation where relative exposure must stay consistent even if focal lengths and sensors differ.