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Exposure Value (EV) Calculator

Convert aperture, shutter speed, and ISO into an exposure value.

Aperture (f-number)

Shutter speed (1 ÷ this value)

1/s

ISO

How it works

EV = log2(N² ÷ t), where N is the f-number and t is the shutter time in seconds. Each +1 EV halves the light, and ISO shifts the value by log2(ISO ÷ 100). Enter the shutter speed as its denominator, so 125 means 1/125 s, and 0.5 means a 2 second exposure. Lux uses the common incident-meter constant of 2.5. Example: f/8 at 1/125 s and ISO 100 gives EV 13, which is about 20,000 lux.

FAQ

Is this calculator free?

Yes. No signup is needed and nothing you enter is stored.

Is the result exact?

Results are rounded for display. For financial, medical, or legal decisions, confirm with a professional.

Do my numbers leave my device?

No. The calculation runs in your browser.