Lens / Focal Length Calculator
Lens / Focal Length CalculatorFind mm lens & FOV from distance. Fast, free and secure — works in your browser. By AK Computer, Dwarka.
Processing...
How to use
- 1 Enter the distance from the camera to the target area.
- 2 Enter the sensor size and desired scene width.
- 3 Read the recommended focal length in millimetres.
- 4 Check the resulting horizontal field of view angle.
Frequently Asked Questions
How do I choose the right lens mm for a CCTV camera?
Enter the distance to the subject and the width you want to cover, and the calculator returns the focal length in mm plus the field of view angle.
Does a higher mm lens mean more zoom?
Yes, a larger focal length narrows the field of view and magnifies distant subjects, while a smaller mm gives a wider but less detailed view.
What lens do I need to read a number plate at a distance?
Number plate capture needs high pixel density on target, which usually means a longer focal length; use the PPM calculator together with this tool to confirm.