CCTV Storage Calculator
Calculate the exact storage capacity required for your IP CCTV system — including RAID overhead, file system allocation, and hard drive count.
Advanced: Mixed Camera Types Enable ▸
When enabled, this overrides the standard inputs above. Enter each camera group separately.
📊 Storage Calculation Results
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How to Calculate CCTV Storage Requirements
A practical, step-by-step guide to sizing storage for IP video surveillance systems — with formulas, bitrate references, RAID explanations, and four fully worked examples covering installations from 16 cameras to 256 cameras.
1. Why Storage Calculation Matters
Storage is typically the most expensive infrastructure component of a CCTV system after cameras themselves. A single 4MP camera recording 24 hours a day at H.265 compression generates approximately 43 GB of data daily. Multiply that across dozens or hundreds of cameras over weeks or months of retention, and the numbers quickly reach tens or hundreds of terabytes.
Under-estimating storage means footage is overwritten before the required retention period expires — a serious compliance issue for banks (RBI mandates 90+ days), PSU offices (typically 60 days), and commercial buildings (30 days typical). Over-estimating wastes budget on unnecessary hard drives. The solution is a simple, repeatable calculation that anyone can verify.
2. The Storage Calculation Formula
CCTV storage calculation involves five variables and three sequential steps:
Daily GB = Bitrate (Mbps) × 10.8
Step 2: Total raw storage
Raw TB = (Daily GB × Number of Cameras × Retention Days) ÷ 1,000
Step 3: Physical disk capacity
Total TB = (Raw TB ÷ RAID Efficiency) × 1.10
The 1.10 multiplier adds 10% for file system overhead
Where does the 10.8 factor come from? It converts megabits per second into gigabytes per day:
3. The Five Key Variables
Variable 1: Number of Cameras
The total count of cameras recording to the storage system. In mixed installations (different resolutions, different areas), group cameras by type and calculate each group separately, then add the totals.
Variable 2: Bitrate (Mbps)
The average data rate of each camera's video stream. This depends on resolution, frame rate, and compression codec. Higher resolution and higher frame rates produce more data. Better compression (H.265 vs H.264) reduces the bitrate significantly.
| Resolution | H.264 @ 15 fps | H.265 @ 15 fps | H.265+ / Smart @ 15 fps |
|---|---|---|---|
| 2MP (1080p) | 3–4 Mbps | 1.5–2.5 Mbps | 0.5–1.5 Mbps |
| 4MP (2K) | 5–8 Mbps | 3–5 Mbps | 1–3 Mbps |
| 5MP | 6–10 Mbps | 4–6 Mbps | 1.5–3.5 Mbps |
| 4K (8MP) | 12–20 Mbps | 8–12 Mbps | 3–6 Mbps |
Variable 3: Retention Period
The number of days video must be stored before the system overwrites the oldest footage.
| Building Type | Typical Retention | Regulatory Driver |
|---|---|---|
| Small offices, retail shops | 15–30 days | No specific mandate; insurance best practice |
| Corporate offices | 30–60 days | Internal security policy |
| PSU / Government buildings | 60–90 days | CVC guidelines, departmental policies |
| Banks & financial institutions | 90–180 days | RBI guidelines on CCTV retention |
| Critical infrastructure | 90–365 days | Sector-specific regulations |
Variable 4: RAID Configuration
RAID (Redundant Array of Independent Disks) protects against hard drive failures by distributing data and parity across multiple drives. The trade-off: RAID consumes a percentage of total disk capacity for redundancy, reducing the usable space.
RAID 5
Usable capacity
Tolerates 1 drive failure
RAID 6 ✓
Usable capacity
Tolerates 2 drive failures
Recommended for CCTV
RAID 10
Usable capacity
Best write performance
Variable 5: Recording Mode
Continuous 24/7 recording uses the most storage but ensures no gaps. Motion-triggered recording saves approximately 30–50% of storage in low-activity areas but risks missing events in the brief seconds before motion is detected. For critical areas, always use continuous recording.
4. Worked Examples
Example 1 — Small Office (16 Cameras)
16 × 2MP cameras, H.265, 30-day retention, RAID 5Example 2 — PSU Office Building (64 Cameras)
64 × 4MP cameras, H.265, 60-day retention, RAID 6Example 3 — Bank Branch (32 Cameras, Mixed Types)
Mixed 2MP/4MP/4K cameras, 90-day retention, RAID 6Camera mix: 20 × 4MP fixed at 4 Mbps + 8 × 2MP corridor at 2 Mbps + 4 × 4K entrance face-capture at 10 Mbps
Example 4 — Enterprise Campus (256 Cameras)
Mixed resolution, 90-day retention, RAID 6, two-tier storage200 × 4MP fixed (4 Mbps) + 32 × 4K entrance (10 Mbps) + 16 × PTZ (6 Mbps) + 8 × ANPR (3 Mbps)
At this scale, a two-tier storage strategy is essential: Tier 1 (live recording, RAID 10, SAS drives, 12–24 hours) + Tier 2 (archive, RAID 6, large SATA drives, 90-day retention). This requires approximately 100 × 20TB surveillance-grade HDDs plus hot spares, distributed across 4–5 SAN storage shelves connected to 4 recording servers.
5. Quick Reference — Storage by Building Type
| Building Type | Cameras | Retention | Approx. Storage (RAID 6) |
|---|---|---|---|
| Small office / Retail | 8–16 | 30 days | 4–15 TB |
| Housing society | 16–32 | 15–30 days | 8–25 TB |
| Corporate office | 32–64 | 30–60 days | 40–140 TB |
| Hospital | 48–96 | 30–60 days | 60–210 TB |
| PSU / Government | 64–128 | 60–90 days | 140–420 TB |
| Bank headquarters | 128–256 | 90–180 days | 420–1,600 TB |
6. Common Storage Sizing Mistakes
- Using datasheet bitrates instead of real-world values. Camera datasheets show bitrates under ideal lab conditions. Real scenes — moving people, changing light, rain — generate 30–50% more data. Always use the higher end of the bitrate range.
- Forgetting RAID overhead. 100 TB of raw storage in RAID 6 provides only 67 TB of usable space. Many vendor proposals quote raw capacity without disclosing the RAID penalty.
- Ignoring file system overhead. The operating system and file system consume approximately 10% of disk capacity. A 16 TB drive provides roughly 14.5 TB of usable formatted space.
- Using desktop hard drives. Consumer drives rated for 55 TB/year will fail within 6–18 months under the 180+ TB/year workload of continuous CCTV recording. Always specify surveillance-grade drives.
- Not planning for hot spares. A RAID array without a hot spare requires manual intervention to begin rebuilding after a drive failure. During the hours or days it takes to source and install a replacement drive, the array operates in a degraded state — vulnerable to a second failure that would cause total data loss.
- Buying all drives from the same batch. Drives from the same manufacturing batch have similar lifespans. Stagger purchases or mix production dates to avoid multiple simultaneous failures at year 3–4.