Sunny 16 Calculator

Sunny 16: in hard sun, f/16 and a shutter of 1/ISO. Slight haze is a stop less light, open shade/overcast two, heavy cloud three. Bright sand or snow is a stop more — faster shutter, not a wider aperture, so you do not blow the whites. It is a starting point. If the sky is not a textbook sky, meter or chimp a test shot.

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Aperture: 16f/
Shutter: 0.010000s
Shutter reciprocal: 100

Recommended gear

Handheld light meter
Sunny 16 is the backup. An incident meter is what you use when the job cannot tolerate a guess.
Typical range: $150–$400
Polarizing filter
A polarizer is about 1–2 stops. If you screw one on, sunny 16 no longer holds until you add those stops back.
Typical range: $20–$80

Calculation method

The rule fixes aperture at f/16. In sun, shutter time is 1/ISO seconds (ISO 100 → 1/100 s). Condition stops scale that time: brighter sand or snow divides time by two (faster shutter); overcast multiplies time (slower shutter) by two, four or eight for −1, −2, −3. Reciprocal is 1/time so you can set 1/125 on a shutter dial.

Exact formula

N = 16. t = (1/ISO) / 2^conditionStops. Reciprocal = 1/t. ConditionStops: +1 sand/snow, 0 sun, −1 slight overcast, −2 overcast, −3 heavy. Limits: Latitude, time of day, polarizer, shade under trees and mixed cloud omitted.

Looney 11

Full moon is roughly f/11 at 1/ISO, not f/16. Eclipses are much darker — use the lunar eclipse calculator, not sunny 16.

Open shade

Open shade is often closer to −3 than ‘slight overcast’. Faces under a tree are not sunny 16 even if the park is in sun.

Frequently asked questions

Can I use f/8 instead of f/16?

Yes — that is two stops more aperture, so double the shutter twice (ISO 100: 1/400 instead of 1/100). This calculator stays on f/16 and only moves shutter with sky condition. Shift aperture separately if you want.

Why not open up for snow?

Snow and sand reflect extra light. The classic rule stops down or speeds the shutter so the whites stay white. Opening up is how you blow the highlights.

Film vs digital?

Same starting point. Digital has a histogram, so you can refine in one test shot. Negative film likes a bit more exposure; slide film likes this number or a hair under.

Disclaimer — no professional advice, no liability

Sunny 16 assumes front-lit midday sun at moderate latitudes. Golden hour, open shade and polarizers will not match. Use it when the meter battery is dead, then verify with a test shot.

These calculators, pages and any related content are provided “as is” and “as available”, solely for general educational and informational purposes. They are simplified mathematical estimates, not a light-meter reading, a studio plot or a shooting prescription, and they do not constitute professional photographic, cinematographic or optical advice.

Results can be wrong, incomplete or inapplicable to your camera, lens, sensor, filter, lighting or use case. You must independently verify every figure, assume all risk, and confirm settings on a test shot before a job that can miss the image, damage gear or injure someone.

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Sunny 16 Calculator

Inputs

Results

Recommended gear

Calculation method

Exact formula

Looney 11

Open shade

Frequently asked questions

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