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Exposure Value Calculator

Work out the exposure value (EV) of any combination of aperture, shutter speed and ISO, or pick a lighting situation and solve for the shutter speed, aperture or ISO you need. A table lists every equivalent exposure so you can trade depth of field for motion blur.

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What do you want to find?
f/

e.g. 1/250, 0.5 or 2 (seconds)

Enter your values to see the result.
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How to use the Exposure Value Calculator

  1. Choose what to find: the EV of your settings, or the shutter speed, aperture or ISO.
  2. Pick the light (scene preset or custom EV) when solving for a setting.
  3. Enter the known settings: f-number, shutter speed (like 1/125) and ISO.
  4. Read the result and the nearest standard setting on your camera.
  5. Use the equivalent exposure table to pick a different aperture or ISO with the same brightness.

Exposure value formula

EV = log₂(N² ÷ t) for aperture N and shutter time t (seconds). Including ISO S: EV₁₀₀ = log₂(N² ÷ t) − log₂(S ÷ 100).

Solving for one setting: t = N² ÷ (2EV × S/100), N = √(t × 2EV × S/100), S = 100 × N² ÷ (t × 2EV). Example: f/8 and ISO 200 on a sunny day (EV 15) → t = 64 ÷ (32,768 × 2) ≈ 1/1,024 s → use 1/1000 s.

EV chart for common lighting (ISO 100)

SceneEV₁₀₀Example setting at ISO 100
Bright sun on snow or sand16f/16, 1/250
Bright sun, distinct shadows15f/16, 1/125
Hazy sun, soft shadows14f/11, 1/125
Cloudy bright, no shadows13f/8, 1/125
Heavy overcast, open shade12f/5.6, 1/125
Just after sunset9–10f/4, 1/60
Bright office, shop windows8f/2.8, 1/30
Home interior5–7f/2, 1/15
Fireworks, distant city lights2–3f/2.8, 2 s
Landscape under full moon−2 to −3f/2.8, 30 s
Milky Way, dark sky−6 or lowerf/2.8, 30 s at ISO 3200

Each step of 1 EV is one "stop": half or double the light. Shutter speeds and apertures on most cameras move in 1/3-stop steps.

Frequently asked questions

What is exposure value (EV)?

EV is a single number for a combination of aperture and shutter speed: EV = log₂(N² ÷ t), where N is the f-number and t the shutter time in seconds. f/1 at 1 second is EV 0. Each +1 EV halves the light reaching the sensor. Combinations with the same EV give the same exposure.

How does ISO change EV?

When EV describes the scene brightness it is usually quoted at ISO 100. Doubling the ISO lets you use settings one EV higher: EV₁₀₀ = log₂(N² ÷ t) − log₂(ISO ÷ 100).

What is the sunny 16 rule?

On a bright sunny day, set the aperture to f/16 and the shutter speed to 1 over the ISO, for example 1/100 s at ISO 100. That combination is about EV 15. Open up one stop for hazy sun, two for cloudy bright and three for heavy overcast.

What EV is a typical indoor room?

A brightly lit home interior is around EV 5 to 7 at ISO 100, offices and stores around EV 8, and floodlit sports stadiums around EV 9. That is why indoor photos need wide apertures, slow shutters or high ISO.

What are equivalent exposures?

Settings that let the same amount of light in: f/8 at 1/250 equals f/5.6 at 1/500 and f/11 at 1/125. Use them to choose more background blur (wider aperture) or more motion blur (slower shutter) without changing brightness.

Why does my camera meter differ from the calculator?

Your meter measures reflected light and aims for a mid-gray result, so very bright or dark subjects push it off. The scene EV values are typical averages; bracket your exposures or check the histogram when it matters.

Are all the tools on FreeToolCabin tested for quality and accuracy?

Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.

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