Visual Angle Calculator

Calculate visual angle, object size, viewing distance, and screen field of view from size, angle, distance, aspect ratio, and resolution.

Choose what you know, then calculate the missing value.

Angle

Size

Distance

Screen FOV

Solve visual angle

Object or image size

Viewing distance

Solve object size

Visual angle

Viewing distance

Primary output unit

Solve viewing distance

Object or image size

Visual angle

Primary output unit

Solve screen field of view

Screen diagonal

Aspect ratio

Viewing distance

Horizontal resolution, optional

Related Calculators

Visual Angle Formula

The following example problem outlines the steps and information needed to calculate the Visual Angle.

VA & = 2((S) / (2D)) \ VA & ≈ (S) / (D) (small angles, in radians)

Variables:

VA is the Visual Angle (radians; multiply by 180/π to convert to degrees)
S is the visual size (the full linear size/extent of the object, e.g., height or diameter)
D is the distance from the eye (or viewpoint) to the object

To calculate the full visual angle of an object, take 2 times the inverse tangent of the object size divided by 2 times the distance. For small angles (when S is much smaller than D), you can use the approximation VA ≈ S/D (in radians).

How to Calculate Visual Angle?

The following steps outline how to calculate the Visual Angle.

First, determine the visual size (full height/width/diameter) of the object.
Next, determine the viewing distance (from the eye to the object).
Next, gather the formula from above: VA = 2×atan(S/(2D)).
Finally, calculate the Visual Angle (and convert to degrees if needed).
After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem :

Use the following variables as an example problem to test your knowledge.

visual size = 30

distance = 20

VA = 2×atan(S/(2D)) = ?

VA = 2×atan(30/(2×20)) = 2×atan(0.75) ≈ 1.2870 radians ≈ 73.7398°