Hobbies: Photo, Music & Garden

Exposure Value (EV) Calculator

Enter the aperture, shutter speed and ISO of a correct exposure.

By TheCalcTools Updated October 17, 2026 Formula checked and tested

Your numbers

Aperture (f-number)

Shutter speed (seconds)

1/250 s = 0.004

ISO

Another aperture to compare

Your results

Exposure value of these settings

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Scene brightness (EV at ISO 100)

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Same exposure at the other aperture (seconds)

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As a fraction

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Typical scene at this EV100

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Exposure Value (EV) Calculator by TheCalcTools

How the Exposure Value (EV) Calculator works

Exposure value combines aperture and shutter speed: EV = log₂(N² ÷ t). Each step of 1 EV halves or doubles the light. All settings with the same EV give the same exposure.

EV100 describes the scene’s brightness: the EV that gives a correct exposure at ISO 100. A higher ISO lets the same scene be shot at a higher EV setting.

The formula

EV = log₂(N² ÷ t); EV₁₀₀ = EV − log₂(ISO ÷ 100)

Worked example

Using the default values shown in the calculator:

Aperture (f-number)	8
Shutter speed (seconds)	0.004
ISO	100
Another aperture to compare	4

f/8 at 1/250 s is EV 13.97.
At f/4 the same exposure needs 1/1000.

Result:

Exposure value of these settings	13.97
Scene brightness (EV at ISO 100)	13.97
Same exposure at the other aperture (seconds)	0.0010
As a fraction	1/1000
Typical scene at this EV100	Hazy or light overcast

Frequently asked questions

What is the sunny 16 rule?

In bright sun, f/16 at 1/ISO seconds is about right: f/16 at 1/100 s at ISO 100 is EV 14.6.

Sources and further reading

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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.