How much storage does a security camera need?
Short answer: Storage depends on bitrate, camera count, and days kept. Use GB per day = bitrate (Mbps) × 86,400 ÷ 8 ÷ 1,000. One camera recording 24/7 at 4 Mbps uses about 43.2 GB a day, or about 1.3 TB for 30 days. Four cameras at that rate need about 5.2 TB for 30 days.
What determines how much storage a camera uses?
Four things set the size of your recordings:
- Bitrate. How many megabits of video the camera writes each second (Mbps).
- Number of cameras.
- Days of footage you want to keep.
- Recording mode. Continuous 24/7 recording or motion-triggered clips.
Resolution, frame rate, and compression all feed into bitrate, which you’ll find in the camera’s video settings or spec sheet.
How do you calculate security camera storage?
Reolink publishes this formula: Storage (GB) = Bitrate (Kbps) × 1000/8 × 3600 × 24 × Cameras × Days ÷ 1,000,000,000.
In Mbps, it simplifies to:
GB per day = bitrate (Mbps) × 86,400 seconds ÷ 8 ÷ 1,000
- 86,400 is the number of seconds in a day.
- Divide by 8 to turn megabits into megabytes.
- Divide by 1,000 to turn megabytes into gigabytes.
Then multiply by the number of cameras and days.
Example: At 2,560 Kbps (2.56 Mbps), one camera recording nonstop uses 2.56 × 86,400 ÷ 8 ÷ 1,000 = about 27.6 GB a day. Over 30 days, that is about 829 GB.
Storage needed for 24/7 recording
These figures assume continuous recording all day, every day. 1 TB = 1,000 GB.
| Bitrate | Per camera per day | 1 camera, 7 days | 1 camera, 30 days | 4 cameras, 7 days | 4 cameras, 30 days | 8 cameras, 7 days | 8 cameras, 30 days |
|---|---|---|---|---|---|---|---|
| 2 Mbps | 21.6 GB | 151.2 GB | 648 GB | 604.8 GB | 2,592 GB | 1,209.6 GB | 5,184 GB |
| 4 Mbps | 43.2 GB | 302.4 GB | 1,296 GB | 1,209.6 GB | 5,184 GB | 2,419.2 GB | 10,368 GB |
| 8 Mbps | 86.4 GB | 604.8 GB | 2,592 GB | 2,419.2 GB | 10,368 GB | 4,838.4 GB | 20,736 GB |
Storage scales in a straight line. Double the bitrate, cameras, or days, and you double the space.
Hard drives are sold in decimal terabytes. Your recorder may show a slightly smaller usable figure. Leave some headroom rather than buying a drive that exactly matches the table.
What bitrate do 1080p and 4K cameras use?
It varies by model, frame rate, and settings. A 4K stream carries about four times the pixels of 1080p, so it generally needs a higher bitrate at the same quality. Check your camera’s settings for the actual value.
Does H.265 save storage over H.264?
Usually. Reolink’s NVR storage guide says “H.265 compression technology leads to better efficiency, which minimizes storage requirements compared to H.264 technology.” Reolink’s formula page also says H.264 can cut file size by “more than 80%” compared with older MJPEG video. The exact H.265 savings depend on the camera and the scene. Busy scenes with trees, rain, or traffic compress less well.
To estimate your savings, switch the camera to H.265 and compare the bitrate it reports.
How much does motion-only recording reduce storage?
It can cut storage sharply, but the amount depends on how much motion the camera sees. A camera on a quiet side yard might record only a small fraction of the day. One facing a busy street could record most of it.
Reolink suggests switching to motion-triggered recording to save space. It also warns that frequent false alarms can eat up a lot of storage. Tighten motion zones and sensitivity to reduce false triggers.
A rough estimate: multiply the 24/7 figure by the share of the day the camera actually records. If it records about 3 hours of clips a day, that is 3 ÷ 24 = 12.5% of the 24/7 total.
Should you use a microSD card, NVR, or cloud?
Single Wi-Fi cameras often record to a microSD card; multi-camera wired systems usually use a hard drive in an NVR. Cloud plans store clips off-site, so footage survives if a thief takes the recorder. For the trade-offs between camera types, see wired vs. wireless security cameras.
Quick answers
How many days of footage will 1 TB hold? One camera at 4 Mbps recording 24/7 uses 43.2 GB a day. So 1,000 GB holds about 23 days for that camera.
Is a 128 GB microSD card enough for a security camera? At 2 Mbps nonstop, one camera fills 128 GB in about 5.9 days. Motion-only recording stretches that much further.
How much storage do 4 cameras need for 30 days? About 2.6 TB at 2 Mbps each, or 5.2 TB at 4 Mbps each, recording 24/7.
Does lowering resolution save storage? It usually lowers the bitrate, which saves space. Lowering frame rate or switching to H.265 can help too.
What happens when the drive is full? Many recorders can overwrite the oldest footage when full, if that setting is on. Check your recorder’s settings.