Exposure calculator · full-stop scales
Exposure Triangle Calculator
Start with an image brightness you want to keep. Protect the part of the look that matters, then change another setting and see what has to move.
Exposure match
Same brightness, different camera choice.
Use this when the photo is bright enough, but the look is wrong. Protect the result you care about, change one setting, and the calculator moves the third setting to keep brightness matched.
Held EV
9.0
Current EV
9.0
Status
Equivalent
Current image
f/4 · 1/250 · ISO 800
What you are doing
Keep the photo the same brightness while changing how it looks.
A correct exposure is the brightness you decide to preserve. The controls beside this image change depth, motion, or noise, then the third setting moves to keep the exposure matched.
Starting image
f/4 · 1/125 · ISO 400
This is the brightness reference the calculator is trying to keep.
Generated reference image. The browser mimics exposure, depth of field, motion blur, and ISO noise as a teaching preview.
What happened
ISO +1 stop. Shutter speed -1 stop. The total is 0 stops, so brightness stays matched.
Depth
Balanced depth
General-purpose focus depth.
Motion
Steady handheld
Good for still subjects.
Noise
Mild noise
Usually manageable.
Stop ledger
The current settings stay matched when the stops cancel.
Read each row as light gained or light removed compared with the starting exposure. A dot to the right adds brightness. A dot to the left removes brightness.
Net result
0 stops
Zero means same brightness.
Aperture
f/4 to f/4
unchanged
Shutter speed
1/125 to 1/250
-1 stop darker
ISO
ISO 400 to ISO 800
+1 stop brighter
Light added
Balance
0 stops
Light removed
Starting exposure
f/4 · 1/125 · ISO 400
Equivalent setting
f/4 · 1/250 · ISO 800
| Setting | Start | Now | Light |
|---|---|---|---|
| Apertureprotected | f/4 | f/4 | 0 stops |
| Shutter speed | 1/125 | 1/250 | -1 stop |
| ISO | ISO 400 | ISO 800 | +1 stop |
| Total exposure change | 0 stops | ||
How to read it
Step 1
Start with brightness to keep
Use a preset or your own settings as the image brightness you want to preserve.
Step 2
Protect one visual result
Protect aperture for depth of field, shutter speed for motion, or ISO for noise.
Step 3
Read the stop ledger
Change one available value. The visual shows what added light, what removed light, and why zero stops means matched brightness.
Frequently asked questions
What problem does this solve?
It solves exposure equivalence. If your brightness is already right but you want a different aperture, shutter speed, or ISO, it shows the setting that keeps brightness matched.
What is a correct exposure?
For this tool, it means the image brightness you want to keep. It is not a moral judgment or a perfect setting, just the starting brightness you are protecting while you change the look.
What does protect mean?
Protect means do not move this setting. If you protect shutter speed, for example, the calculator changes aperture or ISO around it.
What does zero stops mean?
Zero stops means the changes cancel. One setting may add light and another may remove the same amount, so the image brightness stays equivalent.
Why are the controls full stops only?
Full stops make the exposure triangle visible. One click is one doubling or halving of light, which is the cleanest way to learn the tradeoff.
What EV does the calculator show?
It shows the ISO-adjusted exposure value, normalized to ISO 100, so aperture, shutter speed, and ISO are all counted in the result.
Does this simulate the final photo?
No. It is an exposure equivalence calculator. It shows which settings produce the same brightness and explains the tradeoffs for depth, motion, and noise.