How much storage does a CCTV camera need?

At 1 Mbps continuous recording a camera uses about 0.45 GB per hour, or roughly 10.8 GB per day. A 4MP H.265 camera (~4 Mbps) recording 24/7 needs about 43 GB per day, so 30 days of retention is around 1.3 TB per camera.

How do I calculate NVR hard disk size?

Multiply: number of cameras × bitrate (Mbps) × 0.45 × recording hours per day × retention days, then add about 10% headroom and divide by 1000 for TB. ArcisAI’s free calculator does this automatically.

Does H.265 reduce CCTV storage?

Yes. H.265 (HEVC) typically halves the bitrate of H.264 for the same image quality, so it roughly halves the storage required.

Free Tool

CCTV Storage Calculator

Estimate how much recording storage your CCTV / NVR setup needs. Enter your camera count, resolution and retention period — the calculator uses the industry-standard bitrate model (1 Mbps ≈ 0.45 GB/hour) and adds 10% headroom.

Your setup

Number of cameras

Resolution

Codec

Bitrate override (Mbps) — optional, most accurate

Recording hours/day

Retention (days)

Recording density (motion vs continuous)

100%

100% = continuous recording · ~40% = typical motion-triggered recording.

Estimated storage

Total storage required (incl. 10% headroom)

11.4 TB

≈ 10,368 GB raw

Bitrate used

4 Mbps

Per camera / day

43.2 GB

Cameras

Suggested disk

1 × 12 TB drive

Prefer not to manage on-site disks? ArcisAI Cloud VMS offers cloud recording. Share your camera count and retention period with the team to size either option.

Explore Cloud VMS View NVRs Request sizing help

Estimates only. Actual storage varies with scene complexity, frame rate, GOP and VBR/CBR settings. For the most accurate figure, enter your camera's actual configured bitrate in the override field. Calculation: cameras × bitrate(Mbps) × 0.45 × hours/day × retention days × density, +10% headroom; 1 TB = 1000 GB (decimal).

How this CCTV storage calculator works

The estimate multiplies the number of cameras by the recording bitrate, the hours recorded per day and the retention period, then adds 10% headroom. One megabit per second of continuous recording is about 0.45 GB per hour (decimal units, 1 TB = 1000 GB).

Default bitrates used when you do not enter your own: 2MP at 2 Mbps (H.265) or 4 Mbps (H.264); 4MP at 4 or 8 Mbps; 5MP at 5 or 10 Mbps; 8MP (4K) at 8 or 16 Mbps. Real bitrate depends on scene activity, frame rate and encoder settings, so enter your camera's configured bitrate for a closer figure.

Worked example with the default inputs: 8 cameras at 4MP H.265 (4 Mbps), recording 24 hours a day for 30 days. Each camera records about 43.2 GB per day, so 8 cameras for 30 days is about 10,368 GB. With 10% headroom that is roughly 11.4 TB, which fits on one 12 TB drive.

Once you have a figure, you can compare NVR options or ask the team to help size a storage plan. Results are shown on this page without any sign-up.