What is the Sunny 16 rule?

On a sunny day with distinct shadows, set your aperture to f/16 and your shutter speed to 1/ISO. For example, at ISO 100, use f/16 at 1/100s. Adjust the aperture for different lighting conditions: f/11 for slight overcast, f/8 for overcast, f/5.6 for heavy overcast, f/4 for shade.

How accurate is the Sunny 16 rule?

It is surprisingly accurate for outdoor daylight photography, typically within half a stop of a meter reading. It has been used reliably since the early days of photography and remains useful as a quick sanity check even with modern metering systems.

Can I use different apertures with Sunny 16?

Yes. The rule gives you a starting point. You can use equivalent exposures: if f/16 at 1/100 is correct, then f/11 at 1/200, f/8 at 1/400, f/5.6 at 1/800 are all equivalent exposures for the same bright sun condition.

Does the Sunny 16 rule work in the UK?

Yes, though the UK often has softer light than tropical regions. In typical British conditions, you might find yourself using f/11 or f/8 more often than f/16. The rule still provides an accurate starting point.

PhotoCalcs

Sunny 16 Calculator — Quick Exposure Estimates

Use the Sunny 16 rule to estimate exposure settings without a light meter, based on lighting conditions.

Lighting Condition

Select the closest match to your conditions

ISO / Film Speed

How We Calculate This

The Sunny 16 rule states that on a bright, sunny day with distinct shadows:

Aperture: f/16
Shutter speed: 1/ISO

For different conditions, open the aperture: f/11 for slight overcast, f/8 for overcast, f/5.6 for heavy overcast, f/4 for deep shade or sunset. The shutter speed remains 1/ISO in each case.

These correspond to EV values: f/16 = EV 15, f/11 = EV 14, f/8 = EV 13, f/5.6 = EV 12, f/4 = EV 11 (all at ISO 100).

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates based on standard optical and photographic formulas. Results may vary with specific equipment.