Which security camera resolution do you need?

What the numbers mean

A 1080p image is 1920 × 1080 pixels, about 2 megapixels. A 2K image (also called 1440p) is 2560 × 1440, about 3.7 megapixels. A 4K image is 3840 × 2160, about 8.3 megapixels. That is roughly 2.25 times as many pixels as 2K. More pixels let you zoom into recorded video and still see detail, but only if the lens, light and compression keep up.

Match resolution to the job

• Inside one room, 15 feet or less: 1080p or 2K. Extra pixels add little.
• Front door and porch, 10 to 25 feet: 2K is the sensible choice. See doorbell vs door camera.
• Driveway or yard, 30 to 80 feet: 4K or a floodlight camera. See cameras for a driveway.
• Anything beyond 80 feet: use a second camera or optical zoom, since digital zoom on any resolution only enlarges pixels.

What matters as much as resolution

1. Sensor and lens. A larger sensor and a good lens gather more light. A 2K camera with a good sensor can look clearer than a cheap 4K one at night.
2. Night vision. At night, most video falls back to infrared or a spotlight. See infrared vs color night vision.
3. Frame rate. 15 frames per second is acceptable for doors; 20 to 30 is smoother for moving cars.
4. Compression. H.265 (HEVC) stores the same quality in much less space; it offers “25% to 50% better data compression” than H.264.
5. Field of view. A very wide angle spreads pixels thin, so faces at the edges get small.

The cost of 4K: storage and Wi-Fi

A 4K camera produces much more data. On Wi-Fi, a weak signal means stuttering video, dropped clips or the camera cutting its quality. On a PoE network and an NVR, 4K is easy to carry but uses more drive space; size it with the storage calculator. For a microSD card, check the maximum supported size. Battery cameras use more power at 4K and may record shorter clips.

A simple decision path

1. Measure the distance from camera to the farthest area you care about.
2. Under 25 feet: 2K. From 25 to 80 feet: 4K or a floodlight camera. Beyond: add a camera.
3. Choose wired or PoE if you pick 4K.
4. Choose H.265 and enough storage for at least 14 days.
5. Check the app lets you pick lower resolution for live view.

An example: sizing storage for 4K

Bitrate varies by camera, compression and scene, so use the figure from your camera’s spec sheet or app. As a rough illustration, a camera recording at 4 megabits per second uses about 43 gigabytes per day (4 Mbit/s ÷ 8 = 0.5 MB/s, times 86,400 seconds). A 4K stream is often several times that of a 1080p stream. With motion-only recording, a camera might record two to four hours a day instead of 24, which cuts the total to a fraction. The calculator does the math for each camera and for a recorder with several.

Indoor cameras: why lower is fine

Inside a room you rarely need more than 2K. The extra storage and bandwidth buy little, and indoor cameras raise privacy questions: a higher-resolution camera in a bedroom or nursery captures more personal detail. Use a privacy shutter or schedule, disable remote viewing in private areas where the camera allows it, and read indoor cameras and privacy.

Common mistakes

• Paying for 4K and watching it at low quality. Some apps stream a reduced-resolution live view to save data; check that the recording itself is full resolution.
• Ignoring the lens. A very wide field of view, such as 160 degrees, spreads pixels across more scene, so each face is smaller.
• Skipping the pixel math. If your scene is 60 feet wide, a 2K camera gives about 43 pixels per foot, a 4K camera about 64.
• Using a weak Wi-Fi signal. A strong 2K stream beats a stuttering 4K stream.