Field of View Calculator

What Field of View Means for Cameras

Field of view (FOV) describes how much of the world your camera captures. It is the “window” your lens and sensor cut out of the scene. A wide field of view makes rooms look spacious, landscapes feel expansive, and handheld video look more dynamic. A narrow field of view isolates subjects, compresses perspective, and makes distant objects appear larger in the frame.

Photographers and filmmakers often talk about focal length first because that number is printed on the lens. But focal length by itself does not tell the full story. A 50mm lens behaves very differently on a full-frame camera than on a smaller sensor camera. The lens is the same, the focal length is the same, but the sensor crops the image circle and captures a smaller portion of the lens projection. That crop changes the field of view.

This field of view calculator connects the two numbers that actually determine what you see: sensor size and focal length. Once you have those, you can compute horizontal, vertical, and diagonal FOV, estimate scene size at a distance, and plan what focal length you need to match a particular framing.

Field of View vs Angle of View

People use “field of view” and “angle of view” interchangeably. Strictly speaking, angle of view is the angular measurement in degrees. Field of view is often used to describe that angle, and also the practical “how wide is the scene?” question at a given distance. Both ideas are related: if you know the angle, you can calculate the scene width at any distance.

That is why this tool is split into tabs. The first tab focuses on angles (horizontal, vertical, diagonal). The second turns those angles into scene dimensions at a distance. The third tab solves the inverse problem: given a desired angle or a desired scene width, what focal length should you use on your chosen sensor?

The Core Geometry Behind a Field of View Calculator

For a rectilinear lens (the normal “straight lines stay straight” design used by most photography and cinema lenses), the relationship between sensor size, focal length, and angle is well behaved. If you take one dimension of the sensor, such as its width, you can model the lens as projecting a triangle from the lens center to the sensor edges. The half-angle of view is set by:

tan(FOV ÷ 2) = sensor dimension ÷ (2 × focal length)

Solving for FOV gives the standard formula used in most angle-of-view specifications:

FOV = 2 × atan(sensor dimension ÷ (2 × focal length))

This is why you will see three different FOV values for a camera-lens combination. If you use sensor width, you get horizontal FOV. If you use sensor height, you get vertical FOV. If you use sensor diagonal, you get diagonal FOV. None of these are “more correct” in general; they just describe different slices through the same imaging geometry.

Horizontal, Vertical, and Diagonal FOV and When to Use Each

Horizontal FOV is often the most intuitive for framing because most images are judged left-to-right first. If you are fitting a building facade into the frame, estimating how much of a room you can capture, or choosing between 24mm and 28mm for a travel shot, horizontal FOV provides the clearest mental model.

Vertical FOV matters when you are limited by top-to-bottom composition. Portrait orientation photography, tall architecture, interviews framed with headroom, and vertical video all benefit from understanding vertical FOV. If your subject is standing and you want to include their full height at a specific distance, vertical FOV is often the number that controls the decision.

Diagonal FOV is widely used in lens specs because it produces a single number that is easy to compare across formats. It also aligns with the idea of crop factor, which is based on sensor diagonal. If you are comparing cameras with different aspect ratios or planning an “equivalent” look, diagonal FOV is a convenient reference.

Sensor Size: The Hidden Variable Behind “How Wide Is This Lens?”

Sensor size is often described by names rather than exact millimeters: full frame, APS-C, Micro Four Thirds, Super 35, one-inch type, and so on. These labels are useful shorthand, but real sensor dimensions can differ slightly by manufacturer and camera model. That is why this calculator lets you pick a preset for speed and also enter custom sensor width and height for precision.

When you change sensor size while keeping focal length constant, you are not changing the optical magnification of the lens in a physical sense. You are changing how much of the projected image is recorded. A smaller sensor captures a smaller portion of the image circle, which narrows field of view. A larger sensor captures more of the image circle, which widens field of view.

This matters for practical decisions. A 35mm lens on full frame can feel like a moderately wide, natural documentary lens. The same 35mm lens on Micro Four Thirds can feel much tighter, closer to the framing you might associate with a 70mm lens on full frame. The lens did not “become” 70mm; the sensor changed what portion of the image is used.

Crop Factor and 35mm Equivalent Explained Clearly

Crop factor is a ratio that compares the diagonal of your sensor to the diagonal of a full-frame 35mm sensor. Full frame is 36 × 24 mm, with a diagonal of about 43.27 mm. If your sensor diagonal is smaller, the crop factor is larger than 1. If your sensor diagonal is the same, crop factor is 1. If your sensor diagonal is larger (medium format), crop factor is less than 1.

Crop factor is useful because it translates focal length into an “equivalent” focal length that produces a similar field of view on full frame. The common shortcut is:

35mm equivalent focal length = focal length × crop factor

If your camera has a 1.5× crop factor and you use a 35mm lens, the 35mm equivalent is about 52.5mm. That means the field of view you get is similar to what a 52.5mm lens would capture on a full-frame camera, assuming similar rectilinear design and no additional crop.

Equivalent focal length is not a statement about depth of field, noise performance, or “look” in the artistic sense. It is mainly a field of view comparison tool. The reason it became popular is that many photographers learned composition on full frame (or 35mm film), so it is a convenient way to communicate framing between people using different formats.

Scene Size at Distance: Turning FOV Into Real Measurements

Field of view becomes especially practical when you convert it into scene width or height at a known distance. This answers questions like:

• At 3 meters away, how wide will my framing be with a 24mm lens?
• From the back of a room, will I fit the entire group into the shot?
• If my subject is 2 meters wide, what focal length should I use at 5 meters?

Once you have the angle, the scene dimension is computed by basic trigonometry:

Scene dimension = 2 × distance × tan(FOV ÷ 2)

For the rectilinear model used here, this often simplifies nicely because tan(FOV ÷ 2) equals sensor dimension ÷ (2 × focal length). That means scene size is closely related to distance × sensor dimension ÷ focal length. In practice, both forms match within the assumptions of the lens model, and the calculator uses the angle-based approach so the relationship stays clear.

Planning Shots and Lens Choices With the Calculator

A field of view calculator is most valuable when you use it to compare options rather than chasing a single “correct” number. If you are deciding between two focal lengths for an event, plug in both and see how the horizontal FOV changes. If you are matching two cameras for a multi-camera shoot, use the same framing distance and compute what focal length on each sensor produces the same scene width.

For example, imagine you want the same interview framing from the same camera position using two different cameras. Camera A is full frame. Camera B is APS-C. If Camera A uses a 50mm lens, Camera B will likely need a focal length around 33mm to produce a similar field of view (depending on the APS-C dimensions and crop factor). The Required Focal Length tab is designed for exactly this kind of planning.

Why Real Lenses Can Deviate From the Model

The formulas used by a field of view calculator assume a rectilinear projection and an effective focal length that matches the nominal focal length. Real-world behavior can differ:

• Focal length tolerance: Lenses can vary slightly from the printed number, especially zoom lenses across their range.
• Focus breathing: Many lenses change angle of view as you focus closer, which changes real framing.
• In-camera crop: Stabilization, electronic zoom, or different video modes can crop the sensor, narrowing FOV.
• Lens design differences: Fisheye and some ultra-wide designs do not follow the same rectilinear geometry.

That said, the rectilinear model is accurate enough for most lens planning, location scouting, and general framing estimates. When absolute precision matters, measure the real framing or consult detailed lens specifications for your exact camera mode and lens configuration.

Choosing Inputs That Match Your Camera Mode

The most common source of “wrong” results is using sensor dimensions that do not match the active capture area. Many cameras use the full sensor for stills but a slightly cropped area for video. Some use different crops for high frame rates, stabilization, or open-gate modes. If your camera has a known video crop (for example 1.1× or 1.2×), you can account for it by entering a smaller custom sensor width and height (divide the sensor dimensions by the crop factor).

If you are working in cinema contexts, you may be thinking in Super 35 rather than APS-C or full frame. Super 35 itself is not one fixed size; it varies by standard and camera. The preset here is a practical starting point, and custom entry is available if you have exact active dimensions.

How to Use Each Tab Efficiently

Use FOV from Lens when you want angles for a given camera and lens. This is ideal when you have a focal length and want to know how wide it is on your sensor.

Use Scene Size when you want a real measurement at a distance. This is ideal for planning a shot, working out whether a subject will fit, or choosing where to place the camera.

Use Required Focal Length when you have a target field of view or a target scene size and want to know what focal length will match it. This is ideal for matching cameras, reproducing a look, or selecting a lens before you arrive on set.

Use Sensor Presets when you want quick comparisons of crop factor and 35mm equivalents, or when you want to sanity-check how the same lens behaves across different formats.

Practical Examples to Build Intuition

If you want a fast intuition boost, try these patterns:

• Double the focal length, halve the view: Not perfectly linear in degrees, but framing tightens significantly as focal length increases.
• Smaller sensor narrows framing: Put the same lens on a smaller sensor and the scene width at a fixed distance shrinks.
• Distance scales scene size: If you keep lens and sensor fixed, doubling the distance roughly doubles the scene width and height.

Use the calculator to test these quickly. Try the same lens at 2 meters and 4 meters in the Scene Size tab. Then switch between full frame and Micro Four Thirds presets. Seeing the numbers change builds the mental model you need for fast decisions in the field.

Limitations and Best-Use Guidance

This tool is designed for planning and learning. It assumes a rectilinear mapping and uses sensor dimensions you provide. It does not model lens distortion, focus breathing, in-camera crops unless you enter a cropped sensor size, or special lens projections like fisheye. For many use cases, those factors are second-order compared to the primary variables of sensor size, focal length, and distance.

If you want the most accurate results, use the active capture dimensions for your mode, enter the focal length you actually plan to shoot at, and treat the result as a framing estimate. Then adjust based on your real camera test or viewfinder composition.