How is field of view calculated?

The angle of view equals two times the arctangent of the sensor dimension divided by twice the focal length. Horizontal, vertical, and diagonal angles each use the matching sensor dimension or its diagonal.

Why does sensor size change the field of view?

The same lens projects the same image circle, but a larger sensor captures more of it, giving a wider field of view. A 35 mm lens is moderately wide on full frame but a short telephoto on Micro Four Thirds.

What is the crop factor?

Crop factor is the ratio of a sensor's diagonal to full frame's. A smaller sensor crops the image, so multiplying focal length by the crop factor gives the full-frame-equivalent focal length for the same field of view.

How do I find the real-world coverage at a distance?

The frame width equals two times the distance times the tangent of half the horizontal angle of view. The tool computes this for your chosen distance and shows both metres and feet.

Which angle should I use for video?

Video and photography usually frame by the horizontal angle of view since most footage is landscape. The diagonal angle is the traditional photographic figure and is largest, while the vertical matters for tall subjects.

Field of View Calculator

The field of view tells you how much of a scene your lens captures — essential for choosing a focal length before a shoot, planning where to stand, or matching lenses across camera formats. This calculator returns the angle of view in three directions and the real-world frame size at any distance.

How it works

Angle of view depends on the focal length and the sensor dimension in that direction:

angle = 2 × arctan( sensor dimension ÷ (2 × focal length) )

The horizontal angle uses the sensor width, the vertical uses the height, and the diagonal uses √(width² + height²). Because a larger sensor captures more of the lens’s image circle, the same focal length is wider on full frame than on a cropped sensor — that is the origin of the crop factor.

To find real-world coverage at a subject distance d, the tool projects the angle outward:

frame width = 2 × d × tan(horizontal angle ÷ 2)

Worked example

A 35 mm lens on full frame (36 × 24 mm) gives:

horizontal = 2 × arctan(36 ÷ 70) ≈ 54.4°, vertical ≈ 37.8°, diagonal ≈ 63.4°

At 3 m the frame covers about 2 × 3 × tan(27.2°) ≈ 3.08 m wide — roughly enough for a full-body portrait with a little room to spare.

Tips

Use the horizontal angle for video and landscape framing, the vertical for tall subjects, and the diagonal when comparing against the lens maker’s stated figure. To match a look across cameras, multiply focal length by the crop factor: a 35 mm on full frame frames like a 23 mm on APS-C or an 18 mm on Micro Four Thirds.