📷 CCTV Lens Calculator — Focal Length & FOV Tool
Estimate focal length and field of view for CCTV cameras. Values are approximate — verify framing on-site.
f = (sensor_width × distance) / scene_width and FOV = 2·atan(sensor/(2f)).More Tools: Online Tools for CCTV Security Systems
Choosing the correct lens for your CCTV camera is one of the most important steps in designing a reliable security system. A wrong lens can result in a scene that is either too zoomed in or too wide, leading to blind spots and poor image quality.
That’s where our CCTV Lens Calculator comes in. This free online tool helps installers, security professionals, and DIY enthusiasts quickly calculate the right focal length and field of view (FOV) based on distance, sensor size, and desired coverage.
What is a CCTV Lens Calculator?
A CCTV Lens Calculator is a utility that estimates the lens focal length required to capture a specific scene width at a given distance. By entering your camera’s sensor format and installation details, the calculator provides:
- ✅ Required focal length (mm)
- ✅ Horizontal & vertical field of view (FOV)
- ✅ Recommended standard lens sizes (2.8mm, 4mm, 6mm, etc.)
This ensures you select the right lens before purchasing or installing a camera.
Why Lens Selection Matters
Security cameras rely on the lens to determine how much of the scene is visible. The focal length directly affects zoom level and coverage:
- Shorter focal length (2.8mm, 3.6mm) → Wide coverage, less detail
- Longer focal length (8mm, 12mm, 25mm) → Narrow coverage, more detail
For example:
- Use a 2.8mm lens for monitoring wide areas like parking lots.
- Use a 12mm lens to focus on a gate, door, or license plate at a distance.
The right calculation ensures you balance coverage and detail depending on your surveillance goal.
How to Use the CCTV Lens Calculator
Using our tool is simple and takes only a few steps:
- Enter Distance to Target — The distance between the camera and the object/area you want to monitor.
- Enter Scene Width — How wide you want the captured view to be at that distance.
- Select Camera Sensor Size — Common formats include 1/3”, 1/2.8”, and 1/2”.
- Choose Aspect Ratio — 16:9, 4:3, or 1:1, depending on your camera.
- Adjust Precision — Get results with different decimal accuracy.
- Click Calculate — Instantly get focal length, horizontal FOV, vertical FOV, and recommended lens.
Example Calculation
- Distance: 20m
- Scene Width: 10m
- Sensor: 1/3″ (4.8mm × 3.6mm)
Result:
- Required focal length ≈ 9.6mm
- Horizontal FOV ≈ 27°
- Vertical FOV ≈ 20°
- Recommended lens: 12mm
This means a 12mm lens would be the most practical choice for capturing that area.
Features of Our CCTV Lens Calculator
- 🌐 Online and free to use — no installation needed
- 📱 Responsive design — works on mobile, tablet, and desktop
- 🔍 Accurate focal length calculation
- 📊 Field of view (FOV) preview and values
- 📌 Suggested lens sizes for easy selection
- 🛠️ Installer-friendly — made for security professionals
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Conclusion
The CCTV Lens Calculator is a must-have tool for anyone planning or installing security cameras. Whether you are a professional CCTV installer or setting up your own home security system, this tool saves time and ensures you choose the right lens for the job.
👉 Try our free CCTV Lens Calculator today and make sure your surveillance system captures exactly what you need!