Resolution Basics for Security Cameras
Security camera resolution is measured in megapixels (MP) — the total number of pixels in the image sensor. More pixels mean higher potential detail, but the practical benefit depends entirely on how far the camera is from the subject and what size the subject occupies in the frame. A 4K camera aimed at a hallway 100 feet away provides less useful detail of a face than a 2MP camera aimed at a doorway 10 feet away.
Common Resolution Options
| Resolution | Pixel Count | Common Name | Relative Storage |
|---|---|---|---|
| 2MP | 1920×1080 | 1080p / Full HD | 1× (baseline) |
| 4MP | 2560×1440 | 2K / QHD | ~2× |
| 5MP | 2560×1944 | 5 Megapixel | ~2.5× |
| 8MP | 3840×2160 | 4K / UHD | ~4× |
| 12MP | 4000×3000 | 12 Megapixel | ~6× |
The Right Question: How Many Pixels Do I Need on the Subject?
The industry standard measure is Pixels Per Foot (PPF) at the subject distance. Different tasks require different PPF minimums:
- Detection (someone is there): 10–20 PPF — 2MP camera at most ranges
- Recognition (distinguishing individuals): 40–80 PPF — requires 4MP or higher at typical distances
- Identification (positive ID for forensic use): 100+ PPF — requires 4MP–8MP at close range, or 8MP+ at medium range
Practical Resolution Guide by Camera Position
Entry Doors and Lobbies (0–15 feet)
Recommended: 2MP–4MP
At close range, a 2MP camera provides more than enough pixel density for facial identification. Higher resolution adds cost and storage without meaningful benefit at this distance.
Parking Lots and Large Areas (15–50 feet)
Recommended: 4MP–8MP
At 30 feet, a 2MP camera captures approximately 30 PPF of a person — adequate for recognition but not confident identification. A 4MP camera at the same distance provides ~60 PPF, reaching identification-grade quality. For license plate capture in parking areas, 4MP minimum with varifocal lens is standard.
Long Corridors and Wide Open Areas (50–100 feet)
Recommended: 8MP with varifocal zoom
At 75 feet, only 8MP cameras with appropriate focal length provide identification-grade detail. A 4MP camera at 75 feet delivers roughly 25 PPF — recognition quality, but not reliable identification. Deploy 8MP with a 4–8mm motorized lens zoomed to the correct focal length for the specific coverage distance.
Perimeter and Overviews (100+ feet)
Recommended: 8MP–12MP or PTZ
At 100+ feet, even 8MP cameras struggle to deliver identification-grade detail of a single subject. For these distances, PTZ cameras with optical zoom or dedicated long-range cameras with narrow focal lengths are more appropriate. For wide-area overviews where identification isn't required, 4MP is adequate.
The Storage Trade-Off
Higher resolution generates more storage data. A system of all 8MP cameras versus all 4MP cameras (assuming H.265+ compression) will require approximately 2× more storage for the same retention period. Right-sizing resolution — using 4MP where it's sufficient, 8MP only where the coverage distance actually requires it — optimizes both image quality and storage costs.
IDS CCTV's Approach
We specify resolution by camera position based on coverage distance and purpose — not as a flat "all cameras at one resolution" approach. Most commercial systems we design use a mix: 4MP for close-range coverage, 8MP for longer-distance or high-priority positions. Contact us for a camera-by-camera resolution analysis for your site.
