The NVR storage calculation formula
By Devin Chua · Data checked by Owen Nakamura · Updated The formula is: GB per day per camera = bitrate (Mbps) × 3600 × hours ÷ 8 ÷ 1024. Multiply by your camera count and retention days for the footage size, add ~15–25% overhead, then size the RAID array so its usable capacity covers that total. Worked examples and a live calculator are below.
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GB per day, per camera (24/7)
| Resolution | Codec | Bitrate | GB/day | TB/month |
|---|---|---|---|---|
| 1080p (2MP) | H.265 / HEVC | 2–3 Mbps | 26 | 0.8 |
| 1080p (2MP) | H.264 | 4–6 Mbps | 53 | 1.6 |
| 2K / 4MP | H.265 / HEVC | 4–5 Mbps | 47 | 1.4 |
| 2K / 4MP | H.264 | 8–10 Mbps | 95 | 2.8 |
| 4K / 8MP | H.265 / HEVC | 8–12 Mbps | 105 | 3.2 |
| 4K / 8MP | H.264 | 16–24 Mbps | 211 | 6.3 |
Continuous recording at the preset midpoint bitrate. Motion-only and lower frame rates reduce it.
Size it exactly
Pre-filled for this question — change any input to model your own setup.
12.7 TB of footage over 30 days, +20% overhead = 15.2 TB
The formula, term by term
- bitrate (Mbps): your camera's stream bitrate — the single most important input. 1080p H.265 ≈ 2.5, 4K H.265 ≈ 10, and H.264 roughly doubles those.
- × 3600: seconds in an hour, converting bits-per-second into bits-per-hour.
- × hours: hours recorded per day — 24 for continuous, less for scheduled or motion-only.
- ÷ 8: bits to bytes.
- ÷ 1024: megabytes to gigabytes. The result is GB per camera per day.
From per-camera to the array
Total footage = GB/day per camera × cameras × retention days, converted to terabytes. Then add overhead — about 15–25% for the filesystem, database indexes and audio (installers commonly use ×1.25). That gives the usable capacity the array must provide.
The last step is RAID: the array's raw capacity is larger than its usable capacity because parity costs drives. RAID 5 loses one drive to parity, RAID 6 loses two, RAID 1 halves. So size the drives so that usable (not raw) capacity clears your footage total. The calculator does this conversion with the same RAID engine the rest of the site uses, so the TiB numbers are consistent.
A worked example
Four 4K H.265 cameras (10 Mbps), continuous, 30 days: 10 × 3600 × 24 ÷ 8 ÷ 1024 = 105.5 GB/day per camera → × 4 cameras × 30 days = 12,656 GB = 12.7 TB of footage → +20% overhead = ~15.2 TB usable needed → in RAID 5 that is, for example, four 8 TB drives (24 TB usable) or three 12 TB. Change any input in the calculator to see it recomputed.
Frequently asked questions
How do you calculate NVR storage?
GB/day per camera = bitrate (Mbps) × 3600 × hours ÷ 8 ÷ 1024. Multiply by cameras and retention days for the footage size, add 15–25% overhead, then size the RAID array so its usable capacity covers that total. The calculator automates every step.
What is the formula for camera storage?
Storage (GB) = (bitrate in Mbps × 3600 × recording hours ÷ 8 ÷ 1024) × cameras × days × (1 + overhead). The bracket is per-camera daily GB; the rest scales it to your system and retention.
How do I convert camera bitrate to storage?
Multiply the bitrate in Mbps by 3600 (seconds per hour) and the hours recorded, then divide by 8 (bits to bytes) and 1024 (MB to GB) for gigabytes per camera per day. A 10 Mbps 4K camera recording 24/7 comes to about 105 GB a day.
Why add overhead to NVR storage?
Because the recorded video is not the only thing on disk — the filesystem, the NVR's database and indexes, and any audio all take space, and you never want a disk 100% full. Installers commonly add about 25%; the calculator uses an editable 15–25%.
Read more
Devin Chua works out which drives, RAM and NVMe cache fit which NAS model at nasdrives.ca, and what the RAID choice means for usable capacity, checked against what is in stock on Amazon.ca.
Data checked by Owen Nakamura, Technical editor (data checking)