About the Security Camera Storage Calculator
This security camera storage calculator estimates how much hard drive space a CCTV system needs. Enter the number of cameras, their resolution, the video codec (H.264 or H.265), frame rate, how busy the scene is, how much of the day they record and how many days of footage you want to keep. It returns the total storage in terabytes, a sensible drive size to buy, and how many days a drive you already own will hold.
It is meant for homeowners sizing a new NVR, small businesses planning retention for insurance or compliance, and installers quoting jobs. If you know the actual bitrate from your camera’s settings page, switch to a custom bitrate for the most accurate answer — the bitrate is the single number that decides storage.
When you leave the bitrate on automatic, the calculator uses typical main-stream bitrates for H.264 at 30 fps (about 4 Mbps for 1080p and 10 Mbps for 4K), scales them linearly with frame rate, halves them for H.265 and adjusts for scene activity. Real cameras vary with lighting, night-time noise and smart-codec features, so allow some headroom. Capacities are decimal (1 TB = 1,000 GB), the way drives are sold.
With the default inputs, the total storage needed is 2.59 TB. Change any value above to recalculate instantly.
How to use the security camera storage calculator
- 1Enter how many cameras will record to the NVR or DVR.
- 2Pick resolution, codec, frame rate and scene activity — or enter the real bitrate from your camera settings.
- 3Set how much of the day the cameras record (100% for continuous).
- 4Enter how many days of footage you need to keep.
- 5Buy at least the suggested drive size, or check how many days your current drive holds.
Formula and method
Video storage is simply bitrate multiplied by time. A bitrate in megabits per second is converted to bytes per second (divide by 8), multiplied by the 86,400 seconds in a day and by the share of the day the camera records, then by the number of cameras and days of retention. Results are in decimal gigabytes and terabytes, as hard drives are labelled.
In automatic mode the bitrate is estimated as a typical H.264 30 fps main-stream rate for the resolution (720p 2, 1080p 4, 4 MP 6, 5 MP 7, 4K 10 Mbps), scaled by frame rate ÷ 30, multiplied by 0.5 for H.265 and by 0.6, 1.0 or 1.5 for low, medium or high scene activity. Linear frame-rate scaling is slightly conservative, which builds in a little safety margin. The suggested drive adds 10% headroom for file-system overhead and bitrate spikes.
- bitrate
- Average video bitrate per camera (Mbps)
- recording share
- Fraction of each day spent recording
- days
- Retention period (days of footage kept)
Worked examples
8 × 1080p H.265 cameras at 15 fps, 30 days
1080p H.264 at 30 fps is about 4 Mbps; half the frame rate and H.265 bring it to 1 Mbps. That is 10.8 GB per camera per day, so 8 cameras × 30 days = 2,592 GB, about 2.6 TB. Adding 10% headroom (2.85 TB) points to a 3 TB drive, and the default 4 TB drive would hold about 46 days.
4 × 4K H.264 cameras on a busy street, motion recording 50%, 14 days
A busy 4K H.264 scene at 30 fps runs about 10 × 1.5 = 15 Mbps. Recording half the day that is 81 GB per camera per day; 4 cameras for 14 days need 4,536 GB. A 6 TB drive covers it — a 4 TB drive would hold only about 12 days.
16 cameras at a known 2,048 kbps, 90 days
2,048 kbps is 2.048 Mbps, or 22.1 GB per camera per day. Sixteen cameras for 90 days need about 31,850 GB (31.9 TB), more than any single drive, so plan on at least two 20 TB drives.
Frequently asked questions
How much storage does a 1080p security camera use per day?+
At a typical 2–4 Mbps, one 1080p camera recording continuously uses roughly 21–43 GB per day with H.264, and about half that with H.265. Motion-only recording reduces it further.
How many days will a 2 TB drive record?+
It depends on total bitrate. Four 1080p H.265 cameras at about 2 Mbps each write around 86 GB per day, so a 2 TB drive holds roughly 23 days. Use the “drive you have” field for your setup.
Does H.265 really halve storage?+
H.265 (HEVC) typically needs 30–50% less bitrate than H.264 for similar quality. Manufacturer “smart” codecs such as H.265+ can save more on static scenes, but savings drop with motion and night-time noise.
Why does my camera use more storage at night?+
In low light, sensor noise and infrared illumination create fine detail that changes every frame, which the codec cannot compress well. Night bitrates can be noticeably higher than daytime ones, so choose medium or high activity if your cameras run at night.
What hard drive should I use in an NVR?+
Use a surveillance-rated drive designed for 24/7 writing (such as WD Purple or Seagate SkyHawk). Desktop drives are not built for continuous recording and tend to fail sooner.