How many cameras does a typical house need?

Most homes are well covered with 4 to 8 cameras: pedestrian and vehicle entrances, front and rear perimeter, and interior points as the case requires. The exact number comes out of a technical site survey, not a formula. More cameras in the wrong places do not cover better than a few well-planned ones.

Which is better, IP or HD analog cameras?

IP cameras offer higher resolution, video analytics and PoE power, and they are the recommended choice for new installations. HD analog (HD-TVI, AHD, HD-CVI) remains a reasonable alternative when coaxial cabling in good condition already exists or the budget is very tight.

How many days of recording should a CCTV system keep?

For residential and general commercial use, 15 to 30 days of retention is the norm. Some lines of business carry specific local retention obligations, so it is worth checking the regulation that applies to your establishment. An incident is rarely spotted the same day, so anything under two weeks tends to fall short.

What camera resolution do you need to identify a face?

Under the DORI criterion of the IEC 62676-4 standard, identifying an unknown person requires a density of 250 pixels per meter on the target. Recognizing someone already known takes 125 px/m, and detecting presence only 25 px/m. That is why the right question is not how many megapixels the camera has, but how many pixels land on the zone that matters.

Does the H.265 codec really save storage?

Yes. H.265 cuts the data stream by 30 to 50 percent compared with H.264 at equivalent quality, and each manufacturer's smart variants save even more in low-motion scenes. In practice that means doubling the days of retention on the same hard drive.

How to size a CCTV system

Sizing a CCTV system means defining how many cameras are needed, of what type and resolution, and how much storage the recording requires, all starting from a survey of the property. The starting point is not the equipment catalog but three questions: which zones need coverage, what level of detail each one needs, and how many days of video must be kept.

Which is the better fit, IP or HD analog cameras?

IP cameras transmit digital video over network cable and are the default choice for new installations today. They offer resolutions of 4, 8 or more megapixels, video analytics (person and vehicle detection, line crossing), and they draw power over the same cable thanks to PoE. Their infrastructure is the same as a voice and data network, which makes future expansions easier.

High-definition analog cameras (HD-TVI, AHD, HD-CVI) transmit over coaxial cable and commonly reach 2, 5 and even 8 megapixels. They have two concrete advantages: they reuse existing coaxial cabling in good condition, which makes an upgrade cheaper, and they tolerate runs longer than the 100 meters of network cable, since coax handles several hundred meters depending on resolution and equipment. In exchange, they offer fewer analytics and need a separate power cable.

In short: new installation, IP. Upgrade over healthy coax or a very tight budget, HD analog still holds its own. Both technologies can be combined in a single hybrid recorder when the project calls for it.

What resolution does each camera need? The DORI criterion

The right resolution is not chosen by megapixels but by pixel density on the target. The IEC 62676-4 standard defines four levels, known as DORI:

Level	Minimum density	What it allows
Detection	25 px/m	Knowing there is a person or vehicle
Observation	62.5 px/m	Distinguishing general characteristics (clothing, vehicle type)
Recognition	125 px/m	Recognizing a person already known
Identification	250 px/m	Identifying an unknown person with evidentiary value

The same 4 MP camera can identify faces at 8 meters and barely detect presence at 40. That is why manufacturers publish DORI distances for each model and lens, and why an entrance camera (which must identify) is specified differently from a perimeter one (where detecting or observing is usually enough). Asking for “8-megapixel cameras everywhere” without this analysis is the most common way to overpay and still not get a usable image of the face at the door.

How many cameras does a typical property need?

It depends on the property, but there are reasonable orders of magnitude to start from:

House: 4 to 8 cameras (entrances, garage, perimeter, backyard).
Small retail space: 4 to 8 (entrance, register, sales floor, storage or back room).
Single-story office: 8 to 16 depending on square meters and number of entrances.
Warehouse or industrial building: 16 or more, with emphasis on docks, perimeter and high-value zones.
Condominium or gated community: sized by entrances, roadways and amenities, not by number of homes.

These ranges work for preliminary budgeting. The final number comes from the survey: walking the property, marking the zones to cover on a plan, assigning each one a DORI level, and deriving positions, lenses and resolutions from there. In our video surveillance service, that survey is the first stage of every project.

Blind spots are almost never about lacking cameras; they are about placing them badly. The most frequent causes are cameras mounted too high (they see the tops of heads, not faces), lenses narrower than assumed, obstacles that grow or get added later (vegetation, billboards, stacked merchandise), and backlight at entrances, where a person walks in as a black silhouette against the lit street.

The fixes are concrete: mounting heights of 2.5 to 4 meters for scenes where the face matters, overlapping fields of view so each camera covers its neighbor’s lower blind spot, WDR (wide dynamic range) cameras at backlit entrances, and enough infrared or visible light for the night scene. It also pays to verify real coverage on site once the cameras are installed, not just on the plan.

How much storage does the recording need?

Storage is calculated from each camera’s data stream (bitrate) and the desired days of retention. The arithmetic is simple: 1 Mbps of continuous stream generates about 10.8 GB per day. A 4 MP camera recording continuously in H.265 at a typical 2 Mbps produces around 21 GB daily; keeping 30 days demands about 650 GB for that camera alone. A system of 8 similar cameras runs around 5 TB for the same period.

Three variables move that number hard:

The codec. H.265 cuts the stream by 30 to 50 percent versus H.264 at equivalent quality. Each manufacturer’s smart variants (H.265+, Zipstream and the like) save even more in static scenes.
The recording mode. Recording only on motion detection can cut consumption to a fraction of continuous, though in high-risk zones continuous recording with detection as a search index is the recommendation.
The days of retention. For general use, 15 to 30 days is the norm. Certain lines of business carry local retention obligations; check the regulation that applies to your establishment before setting this parameter.

Always use surveillance-line hard drives, designed for continuous writing. A desktop drive in a recorder is a failure waiting to happen.

What is PoE and why does it simplify the installation?

PoE (Power over Ethernet) powers the camera over the same network cable that carries the video, under the IEEE 802.3af (up to 15.4 W) and 802.3at (up to 30 W, needed for PTZ cameras and some models with heaters or strong illumination) standards. The practical benefit is a single cable per camera: no scattered power supplies, no electrical outlets next to every point, and centralized backup, because one UPS at the switch keeps every camera running through a short outage.

The restriction to respect is distance: 100 meters per network cable segment. Longer runs call for an intermediate switch, PoE extenders or fiber optics. That limitation, along with cable quality (certified solid copper, not copper-clad aluminum), is among the first things we check in a survey.

How much does a CCTV system cost?

The cost depends on five factors, in this usual order of impact: number of cameras, equipment type and tier (IP or analog, resolution, brand), cabling and construction complexity (distances, raceways, heights, walls), storage capacity, and complementary work such as UPS units or monitors. Two quotes for “8 cameras” can differ widely and both be correct: one may include new raceways, professional-grade equipment and 30 days of retention, and the other may not.

That is why we publish the factors rather than a single figure. To compare quotes, ask each one to break down equipment, materials, labor and storage, and to specify the brand and model of every component.

Should you install it yourself or hire a specialist?

Self-install kits work for simple needs: two or three Wi-Fi cameras in a house, no cabling, no evidentiary requirements. Their limits show up fast: unstable Wi-Fi coverage, no guaranteed retention, positions limited by where the outlets are, and no DORI engineering behind them.

A wired system with a recorder, raceways and several camera points is a different kind of project. It involves storage calculations, network configuration and proper sealing of outdoor connections, where a good share of premature failures originate. There the professional installer pays for itself, especially one who stands behind the work: in our case, with a 10-year warranty on labor.

What maintenance does a CCTV system need?

Little, but constant. Cleaning domes and lens covers every 3 to 6 months depending on the environment (dust and cobwebs in front of the infrared ruin the night image), periodically confirming that every camera records and that the date and time are correct, checking hard drive health (recorders report bad sectors before total failure), and updating firmware, which on IP equipment is also a cybersecurity matter. A thorough annual review of the whole system, outdoor connections included, prevents most of the failures that reveal a dead system on the very day of the incident.