Digital Camera Settings Calculator

Aperture, shutter speed, and ISO all affect exposure together — change one and you need to change another to compensate. Pick what you want to solve for, enter the other settings and a target exposure value, and get the setting you need.

What do you want to calculate?
Enter Shutter Speed, ISO, and Target EV — Aperture will be calculated.
f/
Shutter speed accepts a fraction (1/250) or seconds (2, or 0.5). Use a period for decimals and commas only as thousands separators.
Result
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Aperture

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The exposure triangle

Three camera settings control how much light reaches the sensor, and each does it a different way. Aperture controls how much light comes through the lens at any instant — a wider opening (a smaller f-number) lets more light in. Shutter speed controls how long the sensor is exposed to that light. ISO doesn't change how much light arrives at all; it controls how much the sensor amplifies whatever light it does receive. Change any one of the three and you can hold the overall exposure constant by adjusting one of the other two.

Exposure value (EV) formula

Exposure Value at ISO 100
EV₁₀₀ = log₂(N² ÷ t)

Here, N is the f-number (aperture) and t is shutter speed in seconds. EV₁₀₀ describes the relationship between aperture and shutter speed independently of ISO. ISO is applied separately: changing from ISO 100 to ISO 400 adds two stops of sensitivity, so the corresponding EV₁₀₀ is two stops higher for the same target exposure.

In this calculator, Target EV represents the exposure value you want to achieve at the selected ISO. The calculator converts it to EV₁₀₀ using EV₁₀₀ = Target EV + log₂(ISO ÷ 100), then uses the standard EV₁₀₀ formula to calculate the required aperture or shutter speed.

For example, with ISO 400, aperture f/4, and a target EV of 10, the calculator first converts the target to EV₁₀₀: 10 + log₂(400 ÷ 100) = 12. It then calculates the shutter speed from t = N² ÷ 2EV₁₀₀, giving exactly 1/256 second. The calculator displays the nearest standard full-stop shutter speed, 1/250 second.

The calculator uses standard full-stop reference values for its primary result. Real cameras may offer additional half-stop or third-stop settings, so the displayed full-stop value is a conventional reference rather than a claim about the exact increments available on every camera. The exact calculated value is shown alongside it.

Frequently asked questions

What does "target EV" mean?

Target EV is the exposure value you're aiming to achieve at the selected ISO. It represents the scene brightness and desired exposure level. The calculator converts the target EV to EV₁₀₀ before calculating aperture or shutter speed. As a general reference, a sunny outdoor scene might be around EV 15, while a dim indoor scene may be around EV 5 or lower.