Exposure Settings and Stops Calculator
Find an equivalent shutter time, aperture or ISO, or compare two camera settings. Separate the light-exposure ratio from the ISO-adjusted brightness index.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
For the same scene, compare t/N² for relative light exposure and t×ISO/N² for an idealized brightness index. Solve the selected target setting to achieve the requested index change, or compare the two complete entered settings.
Light ratio=(tB/tA)(NA/NB)²; brightness-index ratio=light ratio×ISOB/ISOA; stops=log₂(ratio)
Worked example
From f/8, 1/125 s and ISO 100, changing to f/4 at ISO 100 requires 1/500 s for the same brightness index. Keeping f/8 and 1/125 s but changing ISO 100 to 400 changes the index by +2 stops while the light exposure stays unchanged.
Assumptions and input details
Same scene illumination, ideal f-number transmission and linear setting ratios are assumed. ISO does not itself increase the photons reaching the sensor; its contribution is shown separately through a brightness index. Actual rendering, sensor response, clipping, lens transmission, filters, flash, reciprocity failure and camera setting increments are not modeled. Shutter inputs accept positive decimal seconds or fractions such as 1/125, not expressions or camera display abbreviations. Solved values are continuous theoretical settings and may not be available on a camera. EV100-equivalent values normalize the entered settings to ISO 100; they are not a measured scene reading.
References: Fujifilm exposure triangle
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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