Security camera calculators
Work out the right lens, field of view, required internet speed and storage.
How to choose a security camera lens?
The larger the focal length (mm), the narrower the angle of view and the further the camera sees in detail. A 2.8 mm lens covers about 100° and suits a yard or room overview, 4 mm about 85° for an entrance and 6 mm about 55° for details further away. Identifying a person needs about 250 pixels per metre, recognising 125 and observing 62 (DORI, IEC 62676-4).
How much storage do you need?
Storage depends on the number of cameras, resolution, codec and recording mode. A 4 MP camera with H.265 uses about 3.5 Mbit/s, roughly 40 GB a day. Four cameras recording continuously for 30 days need about 5 TB; recording on motion cuts this 2–6 times.
How fast an internet connection do cameras need?
Recordings are stored locally on the recorder, so the internet is only used for viewing on your phone or computer. Normal remote viewing needs about 0.5 Mbit/s upload per camera, full quality needs the camera bitrate. On the local network up to about 25 cameras stay under 100 Mbit/s.
Frequently asked questions
What is the difference between a 2.8 mm and a 4 mm lens?
A 2.8 mm lens sees wider (about 100°), a 4 mm lens narrower (about 85°) but gives about 40% more detail at the same distance.
How far can a 4 MP camera recognise a person?
With a 2.8 mm lens about 10 m, with 4 mm about 15 m and with 6 mm about 22 m (125 pixels per metre).
How big a hard drive do 4 cameras need?
Four 4 MP cameras with H.265 recording continuously need about 5 TB for 30 days, or about 2–3 TB when recording on motion.
Do security cameras need internet?
No. Cameras record locally to the recorder or a memory card. Internet is only needed for remote viewing and notifications; where there is none, a 4G router or a 4G recorder works.