THE NUMBERS, EXPLAINED
How to use this calculator.
Rectilinear lens focused at infinity. Fisheye lenses and focus breathing do not follow this simple model.
Start with your inputs
Enter focal length (mm), sensor width (mm), sensor height (mm). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Focal length (mm) | 50 |
| Sensor width (mm) | 36 |
| Sensor height (mm) | 24 |
A worked example
With the example inputs above, horizontal fov (degrees) is 39.597753. Change the inputs to explore your own scenario.
Putting the example numbers into the formula
Horizontal FOV (degrees)
2 × atan((36) ÷ (2 × (50))) × 180 ÷ π = 39.597753
Vertical FOV (degrees)
2 × atan((24) ÷ (2 × (50))) × 180 ÷ π = 26.991467
| Result | Example answer |
|---|---|
| Horizontal FOV (degrees) | 39.597753 |
| Vertical FOV (degrees) | 26.991467 |
How this is calculated
Horizontal FOV (degrees)
2 × atan(b ÷ (2 × a)) × 180 ÷ π
Vertical FOV (degrees)
2 × atan(c ÷ (2 × a)) × 180 ÷ π
Symbols and units
- a
- Focal length (mm)
- b
- Sensor width (mm)
- c
- Sensor height (mm)
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Calculation steps and notation
atan returns the inverse tangent in radians. Multiply by 180/π for degrees.
π is the circle constant, approximately 3.141592653589793.
Assumptions and limits
Rectilinear lens focused at infinity. Fisheye lenses and focus breathing do not follow this simple model.
Calculations use the values you enter. Blank or invalid inputs show an error instead of silently substituting zero. Results are displayed to useful precision; calculations retain the underlying numeric precision.
Questions about this tool
What does the result tell me?
Horizontal FOV (degrees); Vertical FOV (degrees). The result applies to the method and inputs described above. Check the units and assumptions before using it in a decision.
Why might another calculator differ?
Differences in units, rounding, timing or model definitions can produce different answers. Compare the input definitions and the method, rather than only the final number. For this tool: Rectilinear lens focused at infinity. Fisheye lenses and focus breathing do not follow this simple model.
Are my inputs stored or sent to AI?
Calculations on this page happen in your browser. The separate AI question finder sends its submitted conversation to OpenAI; these calculator fields are not sent. Favourites and recent tool names are stored locally. A shared link contains the inputs you choose to include.
Review status
Software example and browser checks are recorded in our quality report. No external expert review is claimed. Created with coding assistance; calculations run as ordinary browser code.
Read the quality report →