Exposure Value (EV) Calculator

Exposure value (EV) is a single number that pairs an aperture with a shutter speed on a base-2 log scale. The calculator uses EV100 = log2(N squared / t), where N is the f-number and t is the exposure time in seconds.

Yes. A change of one whole EV is exactly one stop, so the light gathered doubles or halves. A higher EV means a brighter scene that needs less exposure to reach the same brightness.

EV is referenced to ISO 100. The tool computes EV at your ISO as EV100 minus log2(ISO / 100), which it also shows as the ISO offset. ISO 800 is three stops above 100, so it subtracts 3 from EV100.

Type it either way. You can enter the fraction 1/250 directly, or the decimal 0.004 seconds. The field parses a leading number, a slash and a denominator, so 1/1000, 1/60 and 1/30 all work.

The calculator rounds each value to four significant figures for readability, so 14.9658 appears as 14.97 and 7.8778 appears as 7.878. EV is a continuous log value, so most real settings land on a fraction rather than a whole stop.

Bright sun is close to EV 15 at ISO 100, which is where the sunny 16 rule comes from. Overcast daylight is nearer EV 12 to 13, open shade around EV 11, and typical indoor lighting falls between EV 5 and 8.

The aperture, shutter speed and ISO must all be greater than zero because EV is a logarithm. If any field is empty, zero, negative or not a number, the tool shows a short prompt instead of a result.

Not on its own. EV describes the exposure that a given aperture and shutter combination produces, not the scene brightness by itself. To match a scene you first meter its brightness, then pick any aperture and shutter pair that sums to that EV.

Yes. Every calculation runs in your browser with no upload, so your camera settings never leave your device.