Sunny 16 Calculator
Estimate exposure without a light meter
Exposure Settings
Lighting Conditions Reference
The Sunny 16 Rule
On a sunny day, set aperture to f/16 and shutter speed to 1/ISO. For example, at ISO 100, use f/16 at 1/100s. Adjust aperture for different lighting conditions while keeping the same shutter speed, or use equivalent exposures.
Sunny 16 — Beyond the Basics
Snow and beach need an extra stop
The standard sunny-day starting point is f/16 at 1/ISO. On sand or snow, that still underexposes because the scene EV runs about 1 stop brighter — jump to f/22, or keep f/16 and halve your ISO. Conversely, backlit subjects (shooting into the sun) drop roughly 2 stops; open to f/8 to hold shadow detail in the face rather than silhouetting your subject.
It still matters with a meter
The real value of Sunny 16 in 2024 is as a sanity check, not a replacement for metering. If your camera's suggested exposure is more than a stop away from the rule in clear daylight, something is wrong — the meter may be fooled by a bright sky, a white background, or a misconfigured mode. Treat the rule as a gut-check that saves you from botched test shots.
Reciprocity holds at low light
The rule assumes ISO = shutter denominator, but the reciprocal relationship extends cleanly to any ISO: at ISO 400 the base is 1/400 s at f/16. The breakdown comes with film at very long exposures (reciprocity failure) — digital sensors don't share that problem, but they do accumulate read noise in extended exposures that the rule doesn't account for.
Frequently Asked Questions
How does the Sunny 16 rule work in practice?
On a clear sunny day with distinct shadows, set your aperture to f/16 and your shutter speed to 1 divided by your ISO. At ISO 200, use 1/200 second. At ISO 400, use 1/400 second. This gives approximately EV 15, matching direct sunlight. You can then trade aperture for shutter speed in equivalent stops to achieve the depth of field or motion effect you want.
What apertures correspond to different lighting conditions in the Sunny 16 system?
Bright sun with distinct shadows calls for f/16. Slight overcast with soft shadows drops to f/11. Full overcast with barely visible shadows is f/8. Heavy overcast with no shadows is f/5.6. Open shade or sunset light is f/4. Each condition is about one stop darker than the previous, so you open the aperture by one stop for each step down the list.
Is the Sunny 16 rule still relevant when cameras have built-in meters?
Yes, for two key reasons. It serves as a sanity check against a malfunctioning or fooled meter (strongly backlit subjects or bright snow trick many evaluative meters into underexposure). It also helps street photographers using manual film cameras pre-set a hyperfocal distance and exposure before an event happens, so they can capture shots without looking through the viewfinder.
Does the Sunny 16 rule work for digital cameras the same way it worked for film?
Yes, because the rule is based on the absolute amount of light in sunlight, which has not changed. Digital sensors have replaced film but the ISO scale was designed to match film’s sensitivity standards, so EV 15 at ISO 100 is the same on digital as on film. The only difference is that digital cameras can instantly review results and correct, whereas film photographers relied on the rule entirely.
What is the biggest mistake photographers make applying the Sunny 16 rule?
Not adjusting for the actual conditions. Many beginners use f/16 on a hazy or lightly overcast day, which is one to two stops too dark, resulting in underexposed images. Always observe shadow quality: distinct hard-edged shadows mean f/16, soft shadows mean f/11, and no shadows at all means f/8 or f/5.6.