What is my lens’s FOV?
Type your lens’s focal length and your camera’s sensor size to see how wide a view it takes in. Or convert a screen’s field of view between vertical and horizontal.
- Horizontal FOV
- 39.6°
The field of view is 39.6° across, 26.99° high and 46.79° on the diagonal.
- Vertical FOV
- 26.99°
- Diagonal FOV
- 46.79°
Horizontal FOV: 39.6°. The field of view is 39.6° across, 26.99° high and 46.79° on the diagonal.
How to calculate
Works out a lens’s horizontal, vertical and diagonal field of view (FOV) from the sensor size and focal length, the area it covers at a distance, and converts a screen FOV between vertical and horizontal for an aspect ratio.
Example with the default inputs (Find Lens FOV, Focal length 50 mm, Sensor width 36 mm, Sensor height 24 mm): The field of view is 39.6° across, 26.99° high and 46.79° on the diagonal.
Method: FOV = 2 × arctan(sensor size ÷ (2 × focal length)), for the width, height and diagonal (√(w² + h²)) of the sensor; covered width = distance × sensor width ÷ focal length. Screen: tan(h ÷ 2) = tan(v ÷ 2) × aspect width ÷ aspect height.
- A rectilinear (not fisheye) lens, focused far away: the image forms one focal length behind the lens. Close focusing narrows the view a little.
- Type the real focal length and the real sensor size, not a 35 mm equivalent.
- The screen mode uses a flat (rectilinear) projection, as games and 3D software do.
Worked examples
Each example is checked against the calculator on every build.
- Find Lens FOV, Focal length 50 mm, Sensor width 36 mm, Sensor height 24 mm gives Horizontal FOV 39.6°, Vertical FOV 26.99°, Diagonal FOV 46.79°.Source: Wikipedia, Angle of view (photography) (α = 2 arctan(d ÷ 2f); a 50 mm lens on a 36 × 24 mm frame: 39.6° horizontal, 27.0° vertical, 46.8° diagonal). https://en.wikipedia.org/wiki/Angle_of_view_(photography), retrieved 2026-10-02: 39.6°, 27.0° and 46.8°; OpenStax, University Physics Volume 3, §2.6 The Camera (thin lens 1/f = 1/dₒ + 1/dᵢ: a distant object images at the focal length). https://openstax.org/books/university-physics-volume-3/pages/2-6-the-camera, retrieved 2026-10-02
- Find Lens FOV, Focal length 24 mm, Sensor width 36 mm, Sensor height 24 mm, Subject distance 10 ft gives Horizontal FOV 73.74°, Width covered 15 ft, Height covered 10 ft.Source: OpenStax, University Physics Volume 3, §2.6 The Camera (thin lens 1/f = 1/dₒ + 1/dᵢ: a distant object images at the focal length). https://openstax.org/books/university-physics-volume-3/pages/2-6-the-camera, retrieved 2026-10-02
- Find Screen FOV, I know the Vertical FOV, Field of view 60°, Aspect width 16, Aspect height 9 gives Horizontal FOV 91.49°, Vertical FOV 60°.
How it works
Lens. For an object far away, the thin-lens equation 1/f = 1/dₒ + 1/dᵢ gives dᵢ = f: the image forms one focal length f behind the lens. A sensor of size d there sees a triangle with half-width d ÷ 2 and depth f, so
FOV = 2 × arctan(d ÷ (2f))
- Horizontal FOV uses the sensor width w, vertical FOV the height h, and diagonal FOV the diagonal √(w² + h²).
- Area covered at a distance D: width = 2D × tan(FOV ÷ 2) = D × w ÷ f, and height = D × h ÷ f.
Screen (games, 3D software). A flat view with horizontal FOV H and vertical FOV V on a screen with aspect ratio W:H′ follows tan(H ÷ 2) = tan(V ÷ 2) × W ÷ H′. The page finds the other angle, then the diagonal FOV from 2 × arctan(√(tan²(H ÷ 2) + tan²(V ÷ 2))).
This page cites OpenStax for the camera optics, which has no angle-of-view formula, and Wikipedia for the formula and its full-frame example.
Rules
- Focal length and sensor sizes are more than 0 and at most 10 m (type mm, cm or in). The subject distance is optional, more than 0 and at most 10⁹ m.
- A screen FOV is more than 0° and less than 180°; aspect parts are more than 0 and at most 1,000.
- A rectilinear lens focused far away. Fisheye lenses and close focusing are not covered.
Output format. Angles in degrees to 2 decimal places; covered width and height to 6 significant figures in feet (meters in Metric).
Worked examples by hand
50 mm lens, 36 × 24 mm sensor. Horizontal: 2 × arctan(36 ÷ 100) = 2 × 19.80° = 39.60°. Vertical: 2 × arctan(24 ÷ 100) = 26.99°. Diagonal: √(36² + 24²) = 43.27 mm, 2 × arctan(43.27 ÷ 100) = 46.79°.
24 mm lens, 36 × 24 mm sensor, subject at 10 ft. Horizontal: 2 × arctan(36 ÷ 48) = 2 × arctan(0.75) = 73.74°. Covered: 10 × 36 ÷ 24 = 15 ft wide and 10 × 24 ÷ 24 = 10 ft high.
Screen, vertical FOV 60°, 16:9. tan(30°) × 16 ÷ 9 = 0.57735 × 1.77778 = 1.02640. Horizontal FOV = 2 × arctan(1.02640) = 91.49°.
Other questions people ask
How do I calculate the field of view of a lens?
FOV = 2 × arctan(sensor size ÷ (2 × focal length)). A 50 mm lens on a 36 × 24 mm full-frame sensor sees 2 × arctan(36 ÷ 100) = 39.6° across and 2 × arctan(24 ÷ 100) = 27.0° from top to bottom.
Why does a shorter focal length give a wider view?
The sensor stays the same size, so moving it closer to the lens (a shorter focal length) lets it take in a wider angle. A 24 mm lens on full frame sees 73.7° across, nearly twice the angle of a 50 mm lens.
How much of a scene fits in the picture at a given distance?
Width covered = distance × sensor width ÷ focal length. With a 24 mm lens on full frame, a subject 10 ft away gives a picture 10 × 36 ÷ 24 = 15 ft wide and 10 ft high.
Does sensor size change the field of view?
Yes. A smaller sensor behind the same lens takes in a narrower angle, which is why smaller sensors are said to have a crop factor. Type your sensor’s real width and height in millimeters.
How do I convert vertical FOV to horizontal FOV in a game?
Use tan(h ÷ 2) = tan(v ÷ 2) × width ÷ height. A vertical FOV of 60° on a 16:9 screen is a horizontal FOV of 2 × arctan(tan 30° × 16 ÷ 9) = 91.5°.
What is the diagonal field of view?
The angle from one corner of the picture to the opposite corner. It uses the sensor’s diagonal, √(width² + height²): 43.3 mm on full frame, so 46.8° with a 50 mm lens.