What is the Sunny 16 rule?

On a clear sunny day, set aperture to f/16 and shutter speed to 1/ISO. For ISO 100 that is 1/100 s; for ISO 400 it is 1/400 s. This gives a correct daylight exposure without a meter.

Why does the table show fractional shutter speeds?

The table calculates the mathematically exact value. In practice you round to the nearest standard speed (1/125, 1/250, etc.). The table flags practical handheld and motion-freeze thresholds to help you choose.

How do I use this for overcast days?

Select "Overcast / no shadows" from the lighting dropdown. The base aperture shifts to f/8 (two stops wider than f/16), which is the traditional Cloudy 8 rule, and the table recalculates all equivalent exposures.

Does this work for digital cameras?

Yes. The Sunny 16 rule is ISO-agnostic and applies equally to digital sensors. Pick your shooting ISO and the lighting condition, then read off any f/stop — shutter speed pair from the table.

What is EV (Exposure Value)?

EV is a single number that represents a combination of aperture and shutter speed at ISO 100. EV 15 is the standard sunny-day value. Each +1 EV halves the light reaching the sensor; each −1 EV doubles it.

Sunny 16 Rule Calculator

Name: Sunny 16 Rule Calculator
Availability: InStock
Author: Nham Vu

Pick your ISO and lighting condition to get a full equivalent-exposure table with every f/stop and shutter speed combination.

Lighting conditions

ISO

Lighting condition

Exposure triangle

All three sides balance to give the same total light.

Base exposure

ISO

400

Aperture

f/16

Shutter

1/400

Equivalent exposure table

Every row gives the same exposure. Choose the aperture that suits your depth-of-field need, then use the corresponding shutter speed.

Aperture	Shutter speed	Practical shutter	Notes

Highlighted row = base Sunny 16 setting Below 1/60 s — use a tripod (handheld blur risk)

Quick reference tips

Each stop opened (e.g., f/16 → f/11) requires halving the shutter speed to keep the same exposure.
Each stop closed (e.g., f/16 → f/22) requires doubling the shutter speed.
To freeze fast motion, aim for 1/500 s or faster — choose a wider aperture to compensate.
For handheld shooting, keep shutter speed above 1/focal-length (e.g., 1/50 s on a 50 mm lens).
Shooting RAW gives about 1–2 stops of post-exposure correction latitude; JPEG gives less.

Summary

Pick your ISO and lighting condition to get a full equivalent-exposure table with every f/stop and shutter speed combination.

How it works

In bright sunlight at f/16, set shutter speed to 1/ISO (e.g. ISO 400 → 1/400 s).
Each f/stop change is one EV; closing aperture one stop requires doubling the shutter speed and vice versa.
Different lighting conditions shift the base aperture; the calculator adjusts the whole table accordingly.
EV is computed as log2(N² / t) where N is the f-number and t is the shutter speed in seconds.
Choose any row in the table — all combinations in the same row give identical exposure.

Use cases

Shooting film without a light meter in known lighting conditions.
Quickly cross-checking your camera meter against the Sunny 16 estimate.
Choosing depth of field and motion blur without changing exposure.
Teaching exposure reciprocity to photography students.
Astrophotography and long-exposure planning using known EV offsets.

Frequently Asked Questions

Last updated: 2026-07-22 · Reviewed by Nham Vu