About this tool
Exposure Value (EV) Calculator is a free, in-browser tool that turns any aperture, shutter speed and ISO into a single exposure value and lists equivalent settings that give the same exposure. Enter your f-number, shutter time (fractions like 1/125 work) and ISO to see the EV instantly. Nothing is uploaded — the math runs on your device.
Exposure value at ISO 100 is EV = log2(N²/t), where N is the f-number and t the shutter time in seconds. Raising ISO lets you meter darker scenes, so the ISO-adjusted value is EV = log2(N²/t) − log2(ISO/100). For example f/16 at 1/125 and ISO 100 gives log2(256/0.008) ≈ 15 — the classic Sunny 16 value. A lighting-reference selector loads a target EV (Sunny 16 = EV 15, cloudy = EV 13, sunset = EV 10, indoors = EV 7) and lists matching aperture and shutter pairs at your ISO.
Use it to swap settings without changing exposure — open up two stops of aperture and the tool shows the faster shutter that keeps the same EV — or to sanity-check a meter reading against known lighting conditions.