Pick your aperture, shutter, and ISO

Choose the aperture (f-number), shutter speed, and ISO you are shooting at. The calculator instantly returns the Exposure Value (EV) for that combination using EV = log2(N² / t). The exposure triangle diagram redraws to show how the three settings balance.

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Read the EV and light condition

The headline number is the EV of your settings; the stat tiles show the ISO-adjusted EV, the scene EV referenced to ISO 100, the depth-of-field band for your aperture, and the matching lighting condition (e.g. "Bright sunlight" near EV 15, "Home interior" near EV 6).

3

Find an equivalent exposure

Turn on "Find equivalent exposures" and open the Equivalent Exposures tab. Every row gives the same EV at your ISO — pick a wider aperture for a blurrier background or a narrower one for front-to-back sharpness, and the matching shutter speed is calculated for you.

Exposure Value (EV)

EV = log2(N² / t)

N is the f-number (aperture) and t is the shutter speed in seconds. EV describes the camera settings independently of ISO. f/16 at 1/125 s gives log2(256 / 0.008) = log2(32000) ≈ 15 — the classic Sunny-16 value.

ISO-adjusted EV

EV_ISO = EV + log2(ISO / 100)

Each doubling of ISO adds one stop (one EV). Moving from ISO 100 to ISO 400 adds log2(4) = 2 EV of sensitivity, so a dimmer scene can be exposed with the same aperture and shutter.

Equivalent exposure

t' = N'² / 2^EV

To keep the same EV (and brightness) at a new aperture N', the shutter time t' must change so that N'² / t' stays constant. Opening up two stops of aperture is offset by two stops of faster shutter.

Video 180° shutter rule

shutter = 1 / (fps × 2)

For natural motion blur in video, set the shutter to roughly twice the frame rate: 24 fps → 1/48 s, 30 fps → 1/60 s, 60 fps → 1/120 s.

Aperture (f-number) The size of the lens opening, written as f/N. A smaller f-number (f/1.8) is a wider opening that lets in more light and produces a shallower depth of field; a larger f-number (f/16) is a narrower opening with more depth of field.

Shutter speed How long the sensor is exposed to light, in seconds (1/125 s, 1/1000 s, or several seconds for long exposures). Faster shutters freeze motion; slower shutters blur it and gather more light.

ISO The sensor's sensitivity to light. Doubling ISO (100 → 200) brightens the image by one stop but also increases visible noise/grain at high values.

Exposure Value (EV) A single number, EV = log2(N² / t), that summarises an aperture/shutter combination. Each whole EV is one "stop" — a doubling or halving of the light reaching the sensor.

Stop A doubling or halving of light. Changing aperture, shutter, or ISO by one stop each has the same one-EV effect on exposure, which is why they can be traded against each other.

Depth of field The range of distances that appear acceptably sharp. Wide apertures (low f-numbers) give a shallow depth of field; narrow apertures (high f-numbers) give a deep one.

Show all 7 terms

Exposure triangle The relationship between aperture, shutter speed, and ISO. Because all three control exposure in stops, raising one and lowering another by the same number of stops keeps the brightness constant while changing the look.

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Daylight landscape

Sunny-16 rule

Aperture f/16 Shutter 1/125 ISO 100

f/16 at 1/125 s and ISO 100 yields EV ≈ 15 — the textbook "Sunny-16" exposure for bright daylight. The narrow aperture keeps the whole landscape sharp. To freeze a faster subject you could open to f/8 and switch to 1/500 s for the same EV.

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Indoor portrait

Window-lit room

Aperture f/2.8 Shutter 1/60 ISO 1600

Indoors there is far less light, so the scene EV (referenced to ISO 100) drops to around 5–6 — "home interior." The wide f/2.8 aperture blurs the background for a flattering portrait, the 1/60 s shutter is just fast enough to stop gentle movement, and ISO 1600 lifts the brightness at the cost of some noise.

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Astrophotographer

Milky Way long exposure

Aperture f/2.8 Shutter 15s ISO 6400

Under a dark sky the scene EV falls below 0. A fast f/2.8 lens, a 15-second shutter (short enough to keep stars as points), and ISO 6400 together collect enough light to record the Milky Way. There is no equivalent fast-shutter combination here — the long exposure is essential.

Every photograph is a balance of three settings — aperture, shutter speed, and ISO. This calculator turns any combination into a single Exposure Value (EV), shows you the lighting it suits, and lists the equivalent settings that produce the same brightness with a different creative look.

How exposure value is calculated

Exposure Value is defined as EV = log2(N² / t), where N is the f-number and t is the shutter speed in seconds. Because it is a base-2 logarithm, every whole EV represents one "stop" — a doubling or halving of the light reaching the sensor.

ISO is layered on top: each doubling of ISO adds one stop of sensitivity, so the calculator reports both the EV of your settings and the scene EV referenced to ISO 100. That ISO-100 figure is what maps to familiar lighting conditions, from EV 15 in bright sun to EV 6 in a living room.

Trading aperture, shutter, and ISO

The power of the exposure triangle is that the three controls are interchangeable in stops. Opening the aperture by two stops and shortening the shutter by two stops leaves the EV — and the brightness — unchanged, but the depth of field becomes shallower and fast motion is frozen.

The Equivalent Exposures tab does this math for you: for each standard aperture it solves t' = N'² / 2^EV and snaps the result to the nearest real shutter speed, flagging whether the depth of field gets shallower or deeper than your current setting.

Depth of field, motion, and video

Aperture also controls depth of field: wide apertures (f/1.4–f/2.8) isolate a subject against a blurred background, while narrow apertures (f/11–f/22) keep a scene sharp front to back. Shutter speed controls motion — 1/1000 s freezes a running athlete, while several seconds blur water into silk.

For video, the 180° shutter rule (shutter = 1 / (fps × 2)) gives motion blur that looks natural to the eye; the DOF Guide tab calculates the target shutter for any frame rate. None of these settings replace a light meter for critical work, but they make the relationships between the three controls concrete.

What is the exposure triangle?+

The exposure triangle is the relationship between aperture, shutter speed, and ISO — the three settings that determine how bright a photo is. Each one controls light in "stops," so raising one and lowering another by the same number of stops keeps the exposure constant while changing the look (depth of field, motion blur, or noise).

What is EV in photography?+

EV (Exposure Value) is a single number that summarises an aperture and shutter combination: EV = log2(N² / t). Higher EV means a brighter scene needs darker settings — EV 15 is bright sunlight, EV 6 is a typical home interior. Each whole EV equals one stop of light.

How do I get an equivalent exposure?+

Keep the EV the same and trade stops between aperture and shutter (or ISO). If you open the aperture two stops, shorten the shutter two stops. This calculator does it automatically: turn on "Find equivalent exposures" and the table lists every aperture with the matching shutter speed at your ISO.

Aperture priority or shutter priority — which should I use?+

Choose aperture priority when depth of field matters most (portraits, landscapes) so you control background blur and let the camera pick the shutter. Choose shutter priority when motion matters most (sports, wildlife, long exposures) so you control freeze-or-blur and let the camera pick the aperture. This calculator shows the trade-off both ways.

Does ISO change the exposure or just the brightness?+

ISO changes how bright the final image is for a given aperture and shutter, but it does not change how much light physically reaches the sensor — that is set by aperture and shutter alone. Raising ISO amplifies the signal (and the noise). That is why this tool reports both the EV of your settings and the ISO-adjusted EV: the first describes the light captured, the second describes the resulting brightness.

Aperture	Depth of field	Typical use
f/1.4 – f/2	Very shallow	Portraits, subject isolation, low light
f/2.8 – f/4	Shallow	Events, food, single subjects
f/5.6 – f/8	Moderate	Groups, street, general use
f/8 – f/11	Deep	Landscapes, architecture
f/16 – f/22	Very deep	Front-to-back sharpness, sunbursts

Shutter	Freezes
1/60 – 1/125	Walking people, gestures
1/250 – 1/500	Kids, pets, casual sports
1/1000 – 1/2000	Running athletes, cars
1/4000 – 1/8000	Birds in flight, splashes
1s – 30s	Intentional blur: water, stars, light trails

Photography Exposure Calculator

Exposure settings

Exposure value

Same EV, different look

Aperture & depth of field

Motion blur & video shutter

Video: the 180° shutter rule

How to Use This Calculator

Pick your aperture, shutter, and ISO

Read the EV and light condition

Find an equivalent exposure

Formula & Methodology

Key Terms Explained

Real-World Examples

Daylight landscape

Indoor portrait

Astrophotographer

Understanding the Photography Exposure Calculator

How exposure value is calculated

Trading aperture, shutter, and ISO

Depth of field, motion, and video

Frequently Asked Questions

Photography Exposure Calculator

Exposure settings

Exposure value

Same EV, different look

Aperture & depth of field

Motion blur & video shutter

Video: the 180° shutter rule

How to Use This Calculator

Pick your aperture, shutter, and ISO

Read the EV and light condition

Find an equivalent exposure

Formula & Methodology

Key Terms Explained

Real-World Examples

Understanding the Photography Exposure Calculator

How exposure value is calculated

Trading aperture, shutter, and ISO

Depth of field, motion, and video

Frequently Asked Questions

Keep Exploring

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