Stops Between Apertures
Find how many stops of light differ between two aperture values.
About Stops Between Apertures
Each stop doubles or halves the light; a smaller f-number means a larger aperture opening and more light. Adding, subtracting and comparing aperture stops is the basic arithmetic of exposure control.
Formula
Stops Between Apertures
Stops = 2 x log2(apertureB / apertureA)
- stops
- A doubling of light equals one stop
Worked example
With the default values below, Stops Between Apertures returns Stops Difference of 2.00. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Aperture Aminimum 0.1
- 2.8
- Aperture Bminimum 0.1
- 5.6
Results
- Stops Difference
- 2.00
- Explanation
- A is 2 stops brighter (smaller f-number)
Step by step
- 1Values used
- 2Stops Between Apertures
- 3Stops Difference= 2.00
- 4Explanation= A is 2 stops brighter (smaller f-number)
Assumptions and limits
- The result is derived only from the 2 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 2 decimal places, 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 Stops Between Apertures calculated?
Stops = 2 x log2(apertureB / apertureA) Each stop doubles or halves the light; a smaller f-number means a larger aperture opening and more light.
Why does Stops Between Apertures matter?
Adding, subtracting and comparing aperture stops is the basic arithmetic of exposure control.
What values do I need to enter?
This calculator takes 2 inputs: Aperture A, Aperture B. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.