Exposure Value (EV) Calculator
Enter your aperture, shutter speed and ISO to get the exposure value. EV is a base-2 scale where each whole number is one stop of light, referenced to ISO 100.
How to use the exposure value calculator
- Enter the aperture f-number.
- Enter the shutter speed in seconds, such as 0.008 for 1/125.
- Enter the ISO and read the exposure value at ISO 100 and at your ISO.
Examples
Sunny 16 rule
f/16, 1/125 s, ISO 100
EV100 = 14.97 (about EV15)
Low light wide open
f/2.8, 1/30 s, ISO 800
EV100 = 7.88, EV at ISO 800 = 4.88
Frequently asked questions
What is exposure value?
Exposure value (EV) is a single number that combines aperture and shutter speed on a base-2 scale. It is defined as log2 of the f-number squared divided by the exposure time.
Is one EV the same as one stop?
Yes. A change of one EV is exactly one stop, meaning the light reaching the sensor doubles or halves. Higher EV means a brighter scene needs less exposure.
How does ISO affect EV?
EV is referenced to ISO 100. Raising the ISO lowers the EV needed for the same exposure, by subtracting log2 of the ISO divided by 100. ISO 800 is three stops, so it subtracts 3.
How do I enter a shutter speed like 1/250?
Enter it as a decimal in seconds. For 1/250 type 0.004, for 1/125 type 0.008, and for 1/60 type about 0.0167.
What is a typical EV outdoors?
Bright daylight is around EV 15 at ISO 100, which matches the sunny 16 rule. Open shade is closer to EV 12 and indoor lighting is often EV 5 to 7.
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