Exposure Value (EV)
Find the exposure value (EV) for a given aperture, shutter speed and ISO.
About Exposure Value (EV)
Exposure value combines aperture and shutter into one number, higher meaning a brighter scene or a lighter exposure. EV offers a shorthand for light levels and lets you reason about exposure without juggling three separate settings.
Formula
Exposure Value (EV)
EV = log2(N^2 / t); normalize with log2(ISO/100)
- N
- Aperture f-number
- t
- Shutter time in seconds
Worked example
With the default values below, Exposure Value (EV) returns EV at this ISO of 9.6. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Aperture (f-number)minimum 0.1
- 2.8
- Shutter speed (1/x s)minimum 1
- 100
- ISOminimum 25
- 100
Results
- EV at this ISO
- 9.6
- EV at ISO 100
- 9.6
Step by step
- 1Values used
- 2Exposure Value (EV)
- 3EV at this ISO= 9.6
- 4EV at ISO 100= 9.6
Assumptions and limits
- The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Exposure Value (EV) calculated?
EV = log2(N^2 / t); normalize with log2(ISO/100) Exposure value combines aperture and shutter into one number, higher meaning a brighter scene or a lighter exposure.
Why does Exposure Value (EV) matter?
EV offers a shorthand for light levels and lets you reason about exposure without juggling three separate settings.
What values do I need to enter?
This calculator takes 3 inputs: Aperture (f-number), Shutter speed (1/x s), ISO. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.