The Sunny 16 rule says that on a bright, sunny day you can expose correctly at f/16 with a shutter speed of 1 ÷ ISO. This calculator extends the rule to every lighting condition — snow and sand, hazy sun, overcast, heavy overcast and open shade — and converts it to any aperture you prefer.
Use it with film cameras, when your meter is fooled by bright backgrounds, or simply to check that your camera's exposure makes sense.
How to use the Sunny 16 Calculator
- Choose the light that best matches the shadows you see.
- Pick your ISO and the aperture you want.
- Use the shutter speed shown; bracket ±1 stop if unsure.
How it works
Shutter = 1 ÷ ISO at the base aperture (f/16 for bright sun). Each stop wider halves the time: t = (1/ISO) × (N ÷ N_base)².
FAQ
Does Sunny 16 work with digital cameras?
Yes. It's a reliable sanity check for any camera, especially in snow or at the beach where meters underexpose.
What about backlit subjects?
Open up 1–2 stops (or use the 'open shade' setting) for subjects in their own shadow.
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