Calculating your exposure value (ev) is straightforward once you know the Exposure Value formula and what each input means. This guide explains the method in plain language, walks through a manual calculation, and gives worked examples you can follow — then you can do it instantly with the Exposure Value Calculator.
What is Exposure Value?
The Exposure Value calculation tells you your exposure value (ev) from a few simple inputs. The figure you are solving for here is the exposure value (ev).
The Exposure Value formula
This calculation combines several inputs through a multi-step method rather than a single one-line formula. Enter the values below and the calculator resolves each step in order. The inputs it needs are:
- Aperture (f-number) — a number. Example: 8.
- Shutter speed — a value measured in seconds. Example: 0.008 seconds.
How to calculate it step by step
- Write down the aperture (f-number) (for example, 8).
- Write down the shutter speed (for example, 0.008 seconds).
- Apply the formula above to get your exposure value (ev).
- Double-check the result with the Exposure Value Calculator.
Worked examples
Example 1
| Input / Output | Value |
|---|---|
| Aperture (f-number) | 8 |
| Shutter speed | 0.008 seconds |
| Exposure value (EV) | 12.97 |
With aperture (f-number) of 8 and shutter speed of 0.008 seconds, the exposure value (ev) works out to 12.97.
Example 2
With aperture (f-number) of 16 and shutter speed of 0.008 seconds, the exposure value (ev) works out to 14.97.
| Result | Value |
|---|---|
| Exposure value (EV) | 14.97 |
Example 3
With aperture (f-number) of 4 and shutter speed of 0.008 seconds, the exposure value (ev) works out to 10.97.
| Result | Value |
|---|---|
| Exposure value (EV) | 10.97 |
Tips for an accurate result
- Keep your units consistent — mixing, say, months with years or grams with kilograms is the most common source of error.
- Round only at the very end. Rounding inputs early can shift the final answer noticeably.
- Re-run the numbers whenever an input changes, rather than estimating from an old result.
Prefer not to do the maths by hand? — the Exposure Value Calculator does it instantly, for free, with the formula and a worked example built in.
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