The exposure triangle links aperture, shutter speed and ISO: change one and you compensate with another to keep the same brightness. Stop down from f/2.8 to f/8, three stops darker, and the shutter must be eight times longer. Enter a known exposure and a new aperture and ISO to get the matching shutter.
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How to Use the Exposure Triangle Calculator
- Enter a known good exposure: its aperture, shutter and ISO.
- Enter the new aperture you want to use.
- Enter the new ISO you want to use.
- Read the shutter speed that keeps the same brightness.
| Result | What it means |
|---|---|
| New shutter speed | The shutter that balances your new aperture and ISO. |
| Scene EV | The exposure value of the scene at ISO 100. |
| Aperture change | How many stops darker or brighter the new aperture is. |
| ISO change | How many stops the ISO change adds or removes. |
What Is the Exposure Triangle?
The exposure triangle is the relationship between the three controls that set image brightness: aperture, shutter speed and ISO. Each changes the exposure in equal steps called stops, and each doubling or halving is one stop of light.
Because they all measure light in stops, they trade off against each other. Let in one stop less light with a smaller aperture, and you can add it back with a longer shutter or a higher ISO. The triangle is how photographers control brightness while shaping depth of field, motion and noise. Understanding it is the moment photography stops feeling like guesswork with a mode dial and starts to feel like a set of deliberate choices, each with a known cost and benefit you can weigh against the shot you are trying to make.
How Does the Exposure Triangle Calculation Work?
new shutter = current shutter x 2^(aperture stops + ISO stops)- Find the aperture change in stops from the two f-numbers.
- Find the ISO change in stops from the two ISO values.
- Add the two for the total stops the shutter must compensate.
- Multiply the current shutter by two to the power of that total.
A smaller aperture or a lower ISO needs a longer shutter to keep the same exposure, and the reverse holds for a wider aperture or higher ISO.
Exposure Triangle Example
You have a good exposure at f/2.8, 1/125 second, ISO 100, and you want more depth of field at f/8. Going from f/2.8 to f/8 is three stops darker, so the shutter must be eight times longer, about 1/15 second, to keep the same brightness. If you instead raised the ISO from 100 to 800, three stops brighter, you could speed the shutter up eightfold instead.
What Affects the Exposure
Aperture
A smaller aperture, a higher f-number, lets in less light and deepens depth of field.
Shutter Speed
A longer shutter lets in more light but risks blur from motion or camera shake.
ISO
A higher ISO brightens the image but adds noise, so it is usually the last resort.
The Trade-Off
Any change in one control can be balanced by an opposite change in another, which is the whole point of the triangle.
Stops Compared Across the Triangle
Each row is one stop, a doubling or halving of light, in each control.
| Stops brighter | Aperture | Shutter |
|---|---|---|
| Reference | f/8 | 1/125 |
| +1 stop | f/5.6 | 1/60 |
| +2 stops | f/4 | 1/30 |
| +3 stops | f/2.8 | 1/15 |
The standard f-stops go f/1.4, 2, 2.8, 4, 5.6, 8, 11, 16, each a full stop apart, because aperture area halves at every step.
When to Use an Exposure Triangle Calculator
Switching Aperture
Keep the exposure when you change aperture for depth of field.
Freezing Motion
Work out the ISO or aperture needed for a faster shutter.
Learning Stops
See how a change in one control balances against another.
Common Exposure Mistakes
1. Changing One Control Only
Adjusting aperture without compensating shutter or ISO changes the brightness.
2. Confusing Aperture Direction
A bigger f-number is a smaller aperture and less light, which feels backwards.
3. Reaching for ISO First
ISO adds noise; adjust aperture and shutter first where you can.
4. Ignoring Motion Blur
A long shutter that balances the exposure may still blur a moving subject.
Accuracy and Limitations
The stop maths is exact and matches how cameras meter. It keeps the exposure equal but does not judge the creative result.
What it calculates accurately
- The shutter that matches a new aperture and ISO
- The stops of change in each control
- The scene exposure value
What it does not do
- Snap the shutter to the nearest camera setting
- Warn about motion blur or noise
- Account for metering modes or filters
How We Calculate the Result
Frequently Asked Questions
What is the exposure triangle?
It is the relationship between aperture, shutter speed and ISO, the three controls that set image brightness. Each measures light in stops, so they trade off against each other.
What is a stop in photography?
A stop is a doubling or halving of light. One stop brighter means twice the light, whether from aperture, shutter or ISO.
How do you keep the same exposure when changing aperture?
Compensate with the shutter or ISO. Stopping down three stops from f/2.8 to f/8 needs a shutter eight times longer to match.
Does ISO change exposure?
Yes. Raising ISO brightens the image in stops just like aperture and shutter, but it adds noise, so it is usually adjusted last.
Why is a bigger f-number less light?
The f-number is a ratio; a larger number means a smaller aperture opening, so it lets in less light and deepens depth of field.
What is exposure value or EV?
EV is a single number for the scene brightness, combining aperture and shutter at a reference ISO. Each unit of EV is one stop.
How many stops between f/2.8 and f/8?
Three stops. The full stops go 2.8, 4, 5.6, 8, so f/8 is three stops darker than f/2.8.
Will the calculated shutter match my camera?
It gives the exact matching value, which may fall between camera settings. Pick the nearest available shutter and fine-tune.
Is my data saved?
No. The calculator runs entirely in your browser and nothing you enter is stored or sent anywhere.
Sources
- Exposure value (Wikipedia).
- Exposure (photography) (Wikipedia).
- F-number (Wikipedia).
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Explore all hobby calculatorsFor photography learning and educational use. Keeps the exposure equal in stops; it does not warn about motion blur, noise or metering, which are creative choices you make. Spotted an error? Let us know.
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