Field of View Calculator
Calculates the horizontal angle of view in degrees for any focal length and sensor width combination. Use it when choosing a lens for a specific framing or comparing cameras with different sensor sizes.
Last updated: May 2026
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About this calculator
Field of view (FoV) is the angular extent of the scene a camera captures, expressed in degrees. The horizontal FoV is calculated as FoV = 2 × arctan(s / (2 × f)) × 180/π, where s is the sensor width in millimeters and f is the focal length in millimeters. Variables: sensor width (e.g., 36 mm for full-frame, 23.5 mm for typical APS-C, 17.3 mm for Micro Four Thirds), focal length in millimeters. A wider sensor or shorter focal length produces a larger angle of view, capturing more of the scene. On a full-frame sensor (36 mm wide) a 50 mm lens gives roughly a 39.6° horizontal FoV, close to normal human central vision. The same 50 mm lens on APS-C yields about 26.5° — equivalent in framing to a 75 mm lens on full frame (the crop-factor effect). Edge cases: the formula gives only the horizontal angle; vertical and diagonal angles require substituting sensor height (24 mm full-frame) or diagonal (43.3 mm full-frame) for s; the formula assumes a rectilinear (standard) lens — fisheye and other curvilinear projections need different equations; focus breathing causes the effective focal length (and thus FoV) to change slightly with focus distance, particularly noticeable in cine lenses.
How to use
Example 1: 35 mm lens on a full-frame sensor (s = 36 mm). Step 1: divide sensor by twice focal length — 36 / (2 × 35) = 36 / 70 = 0.5143. Step 2: take arctan in degrees — arctan(0.5143) ≈ 27.22°. Step 3: multiply by 2 — 2 × 27.22° ≈ 54.43° horizontal FoV. Verify: 35 mm is a popular street-and-documentary focal length precisely because ~54° matches a relaxed natural viewing angle. Example 2: 50 mm lens on an APS-C sensor (s = 23.5 mm). Step 1: 23.5 / (2 × 50) = 23.5 / 100 = 0.235. Step 2: arctan(0.235) ≈ 13.23°. Step 3: 2 × 13.23° ≈ 26.46° horizontal FoV. Verify: APS-C has a 1.5× crop factor — multiplying focal length by 1.5 (50 × 1.5 = 75 mm) and using full-frame width gives 2 × arctan(36/150) ≈ 26.99°, very close to the computed result.
Frequently asked questions
How does focal length affect field of view?
Focal length and field of view have an inverse relationship: shorter focal lengths produce wider angles of view, while longer focal lengths narrow the field of view and magnify distant subjects. For a fixed sensor size, halving the focal length roughly doubles the tangent of the half-angle. Wide-angle lenses (16–24 mm on full-frame) capture expansive scenes, normals (35–50 mm) approximate human central vision, and telephotos (200–400 mm) isolate small portions of distant scenes. Zoom lenses let photographers frame a shot from a single position by simply adjusting focal length. Knowing the FoV in degrees helps you anticipate how a scene will compose before raising the camera.
What is the crop factor and how does it change the effective field of view?
Crop factor is the ratio of a full-frame sensor's diagonal (43.3 mm) to the diagonal of a smaller sensor. An APS-C sensor with a crop factor of 1.5× means a given focal length produces the same FoV as a focal length 1.5× longer would on a full-frame body. So a 35 mm lens on APS-C behaves like a 52.5 mm equivalent on full frame. This is important when comparing lenses across camera systems or trying to replicate a specific framing. Micro Four Thirds uses a 2.0× crop factor, so a 25 mm MFT lens covers the same view as a 50 mm full-frame lens.
Why do photographers calculate field of view when planning a shoot?
Knowing the FoV in advance lets photographers determine how far they need to stand from a subject to fill the frame, or which lens to bring when access or movement is limited. For architecture, a too-narrow FoV may cut off the building; for wildlife, a too-wide FoV makes the subject look tiny in the frame. Pre-calculating FoV is essential when shooting from drones, telescopes, or rigs where changing lenses mid-shoot is impractical. It is also critical when stitching panoramas — knowing each frame's angular coverage tells you how much overlap to leave for clean stitching. Cinematographers use FoV charts to plan camera moves and pre-rig sets.
What are common mistakes when calculating field of view?
Using the sensor diagonal (43.3 mm full-frame) instead of width (36 mm) gives the diagonal FoV, not horizontal — useful but a different number. Ignoring focus breathing in modern photo lenses introduces small errors at close focus distances; cine lenses are explicitly designed to minimize this. Mixing 35 mm equivalent focal length with the actual focal length doubles the crop-factor adjustment. Treating fisheye lenses as rectilinear gives wildly wrong results; fisheye projections cover up to 180° in ways the arctan formula cannot describe. Forgetting that vertical FoV is calculated with sensor height (not width) leads to confused aspect-ratio assumptions for video applications.
When should I NOT use this calculator?
Fisheye lenses use stereographic, equidistant, or equisolid-angle projections rather than rectilinear geometry, so the arctan formula does not describe their FoV accurately. Anamorphic lenses compress horizontally by a factor (typically 1.33× to 2×), so horizontal FoV must be adjusted by the squeeze ratio. Tilt-shift lenses with movements applied have an asymmetric image circle that the simple formula does not capture. Telescope and microscope optics use object-space angles and magnification rather than focal-length FoV math. Video crop modes (e.g., S35 crop within a full-frame sensor) effectively reduce the sensor width — recalculate using the active sensor area, not the physical sensor size.