Exposure Calculator
Calculate Exposure Value (EV) and find equivalent exposures in photography.
The size of the lens opening. A smaller f-number means a larger opening.
How long the sensor is exposed to light. Expressed in seconds or fractions of a second.
The sensor’s sensitivity to light. Higher ISO is more sensitive but can add noise.
Total Exposure Value (EV)
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Light Value (EV at ISO 100)
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Approx. Luminance (cd/m²)
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Stops from “Sunny 16”
| Aperture | Shutter Speed | ISO |
|---|---|---|
| Enter settings above to see equivalents. | ||
Relative light contribution of each setting.
What is an Exposure Calculator?
An exposure calculator is a crucial tool for photographers that helps determine the correct camera settings to achieve a desired exposure for a photograph. It takes into account the three fundamental elements of the exposure triangle: aperture, shutter speed, and ISO. By inputting these values, the calculator computes the resulting Exposure Value (EV), a number that represents the total amount of light captured. A higher EV corresponds to a brighter scene, while a lower EV indicates a darker one. This tool is invaluable for understanding the relationship between settings and for planning shots in manual mode, ensuring a perfect exposure every time. The main goal of this exposure calculator is to provide a clear and quantifiable measure of how bright your image will be.
The Exposure Value (EV) Formula and Explanation
The concept of Exposure Value (EV) standardizes exposure settings into a single number. The formula is based on a logarithmic scale, where each whole number change in EV represents a doubling or halving of the amount of light (a change of 1 “stop”). Our exposure calculator uses the standard formula to combine Aperture (N), Shutter Speed (t), and ISO (S).
The formula for EV at any ISO is: EV = log₂(N² / t) + log₂(S / 100)
This formula is effectively composed of two parts: the “Light Value” (LV), which is the EV at a baseline of ISO 100, and an adjustment for the actual ISO used. This distinction helps photographers separate the light of the scene itself from the sensor’s sensitivity setting. For a detailed guide on this, see our photography exposure guide.
| Variable | Meaning | Unit / Type | Typical Range |
|---|---|---|---|
| N | Aperture F-Number | Unitless ratio (f-stop) | f/1.4 – f/22 |
| t | Shutter Speed | Seconds (s) | 30s – 1/8000s |
| S | ISO Sensitivity | Unitless ISO number | 100 – 25600+ |
| EV | Exposure Value | Stops | -6 to +20 |
Practical Examples
Example 1: Landscape Photography on a Sunny Day
A photographer is shooting a landscape on a bright, sunny day and wants a deep depth of field to keep everything in focus. This scenario is a classic use case for an exposure calculator.
- Inputs: Aperture = f/16, Shutter Speed = 1/125s, ISO = 100
- Calculation: This follows the “Sunny 16” rule. The calculator will show an EV of approximately +15.
- Result: An EV of +15 is standard for direct sunlight. The calculator would confirm these settings are perfect for a well-exposed shot and show equivalent exposures, such as f/8 at 1/500s, if a shallower depth of field was desired.
Example 2: Indoor Portrait with Low Light
For an indoor portrait without a flash, the photographer needs to let in more light. They choose a wide aperture to blur the background.
- Inputs: Aperture = f/1.8, Shutter Speed = 1/60s, ISO = 800
- Calculation: The calculator processes these values: wide aperture (low f-number), relatively slow shutter, and higher ISO.
- Result: The calculator would yield an EV of around +6. It would also generate a table showing that if the photographer wanted less noise at ISO 400, they would need to slow the shutter speed to 1/30s to maintain the same exposure, risking motion blur. This is a key part of understanding the exposure triangle explained in practice.
How to Use This Exposure Calculator
Using this tool is straightforward. Follow these steps to determine your exposure and find creative alternatives:
- Set Your Aperture: Select your desired f-stop from the dropdown. This controls your depth of field.
- Choose Shutter Speed: Select the shutter speed. This controls motion blur.
- Select ISO: Pick your sensor’s sensitivity. This affects image noise.
- Review the Results: The calculator instantly displays the primary Exposure Value (EV), the LV (EV at ISO 100), and other useful metrics. The EV tells you the total brightness of the resulting image.
- Analyze Equivalent Exposures: The table below the calculator automatically populates with different combinations of aperture and shutter speed (at the same ISO) that produce the exact same exposure. This is the most powerful feature for making creative trade-offs. For more details on camera basics, read our camera basics tutorial.
Key Factors That Affect Exposure
- Ambient Light: The most obvious factor. A sunny day (EV 15) requires vastly different settings than a dimly lit room (EV 4).
- Aperture (f-stop): Each full stop change (e.g., f/2.8 to f/4) halves the amount of light entering the lens. It also directly controls the depth of field.
- Shutter Speed: Each doubling of the time (e.g., 1/125s to 1/60s) doubles the amount of light. It’s the primary tool for controlling motion.
- ISO: Doubling the ISO (e.g., 200 to 400) doubles the sensor’s sensitivity, effectively doubling the brightness. The trade-off is increased digital noise. A great guide on this is our article on ISO settings guide.
- ND Filters: Neutral Density filters reduce the amount of light entering the lens without changing its color. This allows for wider apertures or slower shutter speeds in bright light.
- Time of Day: The “golden hour” near sunrise and sunset has a much lower EV than midday sun, offering softer, warmer light.
Frequently Asked Questions (FAQ)
- What is a “stop” of light?
- A “stop” is a measurement of light. Increasing exposure by 1 stop means doubling the amount of light reaching the sensor. Decreasing by 1 stop means halving it. Our exposure calculator shows this relationship in the equivalent exposures table.
- What is the difference between EV and LV?
- LV (Light Value) is the EV of a scene at a baseline of ISO 100. EV (Exposure Value) is the actual exposure of your final image, accounting for your chosen ISO. This calculator shows both.
- What is the Sunny 16 Rule?
- It’s a guideline for estimating correct exposure in daylight without a light meter. It states that on a sunny day, you should set your aperture to f/16 and your shutter speed to the reciprocal of your ISO (e.g., ISO 100 at 1/100s or 1/125s). This combination results in an EV of about 15.
- How do I use the equivalent exposures table?
- Once you have a good exposure, the table shows you other settings that achieve the same brightness. For example, if you want more background blur, find a row with a wider aperture (smaller f-number) and see the corresponding shutter speed needed to compensate.
- Why is my photo still dark/bright even with the right EV?
- Your camera’s light meter can be fooled by scenes with a lot of white (like snow) or black. You may need to use exposure compensation (+/- EV button on your camera) to correct for this. Understanding what is EV in photography helps diagnose these issues.
- Can this calculator account for a flash?
- No, this exposure calculator is for ambient light only. Flash exposure is more complex as it depends on flash power, distance to subject, and flash sync speed.
- Does a higher EV always mean a better photo?
- Not at all. The “correct” EV is subjective and creative. Low-key photography intentionally uses low EV for dark, moody images, while high-key uses high EV for bright, airy shots. The calculator gives you a technical baseline, not an artistic mandate.
- How does focal length affect exposure?
- Focal length itself does not affect exposure. However, some zoom lenses have a variable maximum aperture that changes as you zoom, which would require you to adjust other settings to maintain the same EV.
Related Tools and Internal Resources
If you found this exposure calculator helpful, explore our other resources for photographers:
- Landscape Photography Tips: Master the art of capturing stunning scenes, from composition to gear.
- Portrait Lighting Setup: A guide to classic lighting techniques for creating professional portraits.
- Understanding Aperture: A deep dive into f-stops, depth of field, and creative control.
- Mastering Shutter Speed: Learn how to freeze action or create beautiful motion blur.