Photography Exposure Calculator
Solve for aperture, shutter speed, or ISO from the other two exposure triangle values and a target exposure value (EV).
EV 12-15 is typical for bright daylight; EV 5-8 for indoor/overcast
Aperture
f/5.7
Understanding the Exposure Triangle
Every photo's exposure (how bright or dark it looks) is controlled by three settings, known as the exposure triangle: aperture (the f-stop, controlling how much light the lens opening lets through), shutter speed (how long the sensor is exposed to light), and ISO (the sensor's sensitivity to light). Changing any one of them changes the exposure — but each also has a side effect: aperture affects depth of field (background blur), shutter speed affects motion blur, and ISO affects image noise/grain. Photographers balance all three to get the exposure they want with the trade-offs they can live with.
How This Calculator Works
Exposure Value (EV) is a single number that represents a specific combination of aperture and shutter speed at ISO 100 — the brighter the scene, the higher the EV needed to avoid overexposure. Enter any two of the three exposure triangle values plus your target EV, and this calculator solves for the third value using the standard photographic exposure formula.
Where N is the f-number (aperture), and t is the shutter speed in seconds.
Example
At f/8 and ISO 100 with a target EV of 12 (typical bright, hazy daylight), solving for shutter speed gives approximately 1/250s. If you instead wanted to solve for aperture at 1/250s and ISO 100 with the same EV of 12, you'd get back f/8.
Common Use Cases
- Working out an equivalent exposure when you want to change aperture for depth of field.
- Finding the right shutter speed to freeze or blur motion at a given aperture and ISO.
- Learning how the exposure triangle trades off in manual mode.
FAQs
What is Exposure Value (EV)?
EV is a number that combines aperture and shutter speed into a single value representing the total amount of light reaching the sensor at ISO 100. The same EV can be achieved with many different aperture/shutter combinations — a stop faster shutter with a stop wider aperture gives the same EV (this is called an "equivalent exposure").
Do I need to know the exact EV for my scene?
Not exactly — most cameras display an exposure meter reading (often relative to 0, meaning "correctly exposed" for the camera's current settings) which you can use as a starting point, or use common EV reference guides for lighting conditions (e.g. EV 15 for bright sun, EV 5 for typical indoor lighting).
Why does my shutter speed input need a slash, like 1/125?
Shutter speeds are usually written as a fraction of a second. You can enter it as a fraction (like 1/125) or as a decimal number of seconds (like 2 for a 2-second exposure) — both formats work.