EV (Exposure Value)
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
log₂(N²/t)
About this calculator
The Exposure Value (EV) calculator helps photographers determine the optimal combination of aperture and shutter speed for proper exposure. The formula EV = log₂(N²/t) links aperture (N) and exposure time (t), converting these values into a linear scale. This allows standardized comparison of different camera settings.
Use this tool mainly in manual photography or when adjusting natural light. For example, when landscape photography, adjusting EV helps avoid overexposure on sunny days or underexposure in shaded environments. The result indicates whether the current setting favors more light (low EV) or less light (high EV).
Caveats: The formula does not account for ISO, which also affects exposure. Additionally, ambient light with high or low intensity may require manual adjustments beyond the calculation. Always review your camera's histogram to confirm ideal exposure.
Frequently asked questions
What is Exposure Value (EV)?
It is a metric that combines aperture and shutter speed into a logarithmic scale, allowing comparison of different camera settings.
How does the formula EV = log₂(N²/t) work?
It converts the relationship between aperture squared and the inverse of shutter speed into a linear scale for exposure analysis.
Why isn't ISO included in the formula?
Traditional EV does not account for ISO, which is an image amplification factor. It's only relevant in modern exposure calculations.
Can I use EV in automatic photography?
Not directly, since automatic cameras handle EV internally. This tool is more useful for manual or semi-manual modes.
How to apply the calculation result?
Manually adjust your camera's aperture and shutter speed until the calculated EV aligns with your desired exposure.