Sunny 16 Exposure Table Calculator

Pick your ISO and lighting condition to get Sunny 16 exposure settings.

Result

f/5.6 at 1/400 s, ISO 400 (Heavy overcast)
f/5.6
1/400 s

How it is calculated

The shutter speed is always the reciprocal of the ISO: shutter = 1 / ISO seconds, using the ISO rounded to a whole number. The aperture comes from a table of lighting conditions, each one stop wider than the last: sunny f/16, slight overcast f/11, overcast f/8, heavy overcast f/5.6 and open shade f/4. The tool shows a one-line summary plus the aperture and the shutter speed separately. ISO must be above zero, otherwise there is no result. An unrecognised condition is treated as sunny. The shutter is not rounded to the nearest standard camera speed, so ISO 160 shows 1/160 s even though your camera may only offer 1/125 or 1/200; pick the closest. Equivalent exposures are also fine: opening one stop and halving the exposure time give the same result.

Worked example

You load ISO 400 film and the sky is heavily overcast. The shutter follows the ISO: 1/400 s. The condition table gives the aperture for heavy overcast: f/5.6. The tool's summary reads f/5.6 at 1/400 s, ISO 400 (Heavy overcast). If the sun came out, the same film would need f/16 at 1/400 s, three stops less light than f/5.6 lets in (f/5.6, f/8, f/11, f/16), so you would stop the lens down from f/5.6 to f/16.

Try this example →

Common mistakes

  • Using the rule for backlit or indoor scenes: it is calibrated for ordinary front or side lit outdoor subjects, not strong backlight or interiors.
  • Picking sunny when the sun is behind thin cloud: the aperture then comes out about a stop too small and the frame is underexposed.
  • Entering the ISO as the film's box speed when you plan to push or pull development; enter the speed you actually expose at.
  • Expecting the shutter to snap to a standard value: at ISO 160 the tool says 1/160 s, so choose the nearest speed your camera has.
  • Applying the table at sunrise or sunset: the low sun is much dimmer than the table assumes.

About this calculator

The Sunny 16 rule is a decades-old photographer's shortcut for setting exposure without a light meter: on a bright sunny day, set the aperture to f/16 and the shutter speed to the reciprocal of the ISO (so ISO 100 gets 1/100s, ISO 400 gets 1/400s), and the result will be correctly exposed. It works because f/16 at 1/ISO delivers a consistent, predictable amount of light for direct sunlight conditions, independent of camera brand or meter behavior.

For less intense light, the rule extends into a table: each stop cloudier moves the aperture wider by one stop while keeping the same shutter speed — roughly f/11 for slight overcast, f/8 for overcast, f/5.6 for heavy overcast, f/4 for open shade — since one stop wider lets in double the light to compensate for the dimmer conditions. This calculator picks the right f-stop for your lighting condition from that table and sets the shutter speed from your ISO, useful for manual film cameras or as a sanity check on a digital meter reading.

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