By the SightShield team · · 3 min read
Megapixels in plain terms
A camera’s resolution is the number of pixels in each frame. More pixels means more detail across the same view — or the same detail across a wider view. That is the real trade-off: resolution decides how far away, or how wide an area, the camera can cover while still showing a face or an object clearly.
Resolution is only one part of image quality. The lens, the sensor size, the lighting and the compression all matter. A 2MP camera with a good sensor and the right lens often gives a more useful picture than a cheap 4MP camera placed badly.
The common resolutions
| Resolution | Pixels (approx.) | Also called | Typical use |
|---|---|---|---|
| 2MP | 1920 × 1080 | 1080p, Full HD | Rooms, corridors, small shops, budget systems |
| 4MP | 2560 × 1440 | 1440p, 2K | The usual choice today for homes, offices and entrances |
| 5MP | about 2560 × 1944 | 5MP | Mostly HD analog systems wanting more detail |
| 8MP | 3840 × 2160 | 4K, Ultra HD | Wide yards, parking, large halls, long boundary views |
How resolution affects identification
Security professionals use pixel density — how many pixels fall across one metre of the scene — to decide what a camera can do. The international CCTV standard IEC 62676-4 describes four levels, often called DORI:
- Detect (about 25 pixels per metre): you can tell something or someone is there.
- Observe (about 63 px/m): you can see what a person is doing and some clothing detail.
- Recognise (about 125 px/m): someone who knows the person can recognise them.
- Identify (about 250 px/m): enough detail to identify an unknown person beyond reasonable doubt.
What that means in practice
Take a camera covering a gate 4 metres wide. To identify faces you need about 250 pixels per metre, so 4 m × 250 = 1,000 pixels across. A 2MP camera has 1,920 pixels across, so it can identify faces across that gate with room to spare. Now widen the view to cover a 12-metre compound: you need 3,000 pixels across for identification, which only an 8MP camera comes close to. At 2MP, the same view only reaches "observe".
This is why the right answer is often "a 4MP camera at the gate aimed tightly at the entry point, plus a wider camera for the compound" rather than one high-resolution camera trying to do both jobs.
The cost of more megapixels
- Storage: a 4MP camera typically uses around twice the storage of a 2MP camera, and 8MP around four times. For the same number of recording days you need a bigger disk.
- Low light: packing more pixels onto a small sensor can make night images noisier. Good 4MP and 8MP cameras use larger sensors to compensate; cheap ones may not.
- Recorder: your DVR or NVR must support the resolution, and higher resolutions need more bandwidth per channel.
- Viewing: remote viewing on a phone uses a lower-quality sub-stream anyway, so the benefit of 8MP shows up mainly in recorded playback and zoom.
Our recommendations by location
| Location | Suggested resolution | Why |
|---|---|---|
| Main gate or entrance door | 4MP, narrower lens | Identify faces at the entry point |
| Living room, office cabin, corridor | 2MP or 4MP | Short distances; detail is easy |
| Shop counter or cash desk | 4MP | See notes, products and hands clearly |
| Compound, parking, yard | 4MP to 8MP | Wide area with useful detail |
| Warehouse aisle | 4MP with varifocal lens | Long, narrow view from height |
| Long boundary wall | 4MP with line-crossing | Detection over distance, plus alerts |
The bottom line
For most homes and businesses in 2026, 4MP is the sensible default: clearly better than 2MP for identification, without the storage cost and night-time compromises of 8MP. Use 8MP where one camera has to cover a genuinely wide area, and keep 2MP for budget systems and short indoor views. Above all, decide what each camera must achieve — detect, recognise or identify — and pick the resolution and lens to match.
Get a camera-by-camera plan for your site →Quick answers
Is 2MP CCTV good enough?+
For indoor rooms, corridors and short distances, yes. For entrances and wider outdoor areas where you need to identify people, 4MP is noticeably better.
Does an 8MP camera see further at night?+
Not necessarily. Night range depends on the infrared or white-light range and the sensor. 8MP gives more detail when there is enough light.
Can I use 4MP cameras on my old DVR?+
Only if the DVR supports 4MP input. Many older DVRs are limited to 2MP or will record 4MP at reduced quality. Check the DVR model first.
How much more storage does 4MP need than 2MP?+
Roughly twice as much for the same settings. With H.265 compression, a 4MP camera recording 24×7 typically uses around 20 GB a day.