How to Calculate CCTV Storage Requirements

The CCTV Storage Calculation Formula

The fundamental formula for calculating CCTV storage requirements is:

Storage (GB) = Bitrate (Mbps) × 3,600 × Hours per Day × Retention Days × Number of Cameras ÷ 8,000

This formula gives you the total raw storage needed. In practice, you should add a 15-20% overhead for file system formatting and operational headroom.

Factors That Affect Storage

Resolution

Higher resolution cameras produce larger video files:

Frame Rate (FPS)

Higher frame rates provide smoother footage but increase storage proportionally:

• 15 FPS: Acceptable for general surveillance; reduces storage by 40% vs 25fps
• 25 FPS: Standard for most applications; required by SIRA and MCC for primary cameras
• 30 FPS: Used in high-security environments (banks, casinos)

Codec (Compression)

The video compression codec makes a dramatic difference in storage requirements:

• H.264: Older standard, widely compatible, higher file sizes
• H.265 (HEVC): 40-50% smaller files than H.264 at the same quality — strongly recommended
• H.265+/Smart Codec: Proprietary enhancements that can reduce storage by an additional 30-50% using scene-adaptive encoding

Retention Period

Storage requirements scale linearly with retention days:

• 30 days: Standard requirement for SIRA and MCC
• 90 days: Required for banks, government, and critical infrastructure
• 180+ days: Some financial regulations require extended retention

Example Calculations

Example 1: Small Office (8 cameras)

• 8 cameras × 2MP × H.265 @ 25fps
• Bitrate per camera: ~3 Mbps
• Recording: 24/7 continuous
• Retention: 30 days

Storage = 3 × 3,600 × 24 × 30 × 8 ÷ 8,000 = 7,776 GB ≈ 8 TB

Example 2: Large Commercial Building (64 cameras)

• 48 cameras × 4MP + 16 cameras × 2MP, all H.265 @ 25fps
• Bitrate: 5 Mbps (4MP) and 3 Mbps (2MP)
• Recording: 24/7 continuous
• Retention: 30 days

Storage = [(5 × 48) + (3 × 16)] × 3,600 × 24 × 30 ÷ 8,000 = 85,536 GB ≈ 86 TB

Example 3: Bank Branch (32 cameras, 90-day retention)

• 32 cameras × 4MP × H.265 @ 30fps
• Bitrate per camera: ~6 Mbps
• Recording: 24/7 continuous
• Retention: 90 days

Storage = 6 × 3,600 × 24 × 90 × 32 ÷ 8,000 = 59,719 GB ≈ 60 TB

Common Mistakes

• Using motion recording in calculations: SIRA and MCC require continuous recording — always calculate for 24/7
• Forgetting RAID overhead: RAID 5 uses ~25% of raw storage for parity; RAID 6 uses ~33%
• Not accounting for codec overhead: Real-world bitrates vary with scene complexity — use peak bitrates, not averages
• Ignoring growth: Plan for future camera additions (add 20-30% buffer)
• Using manufacturer marketing numbers: Quoted "Smart H.265+" savings are best-case — use standard H.265 bitrates for calculations

How Securify Handles Storage Calculations

Securify eliminates manual storage calculations entirely:

• Automatic calculation: As you add cameras to your design, storage requirements update in real-time
• Per-camera bitrate modeling: Accounts for each camera's resolution, FPS, and codec individually
• RAID overhead included: Factors in your chosen RAID level automatically
• Compliance validation: Flags if your storage capacity doesn't meet the required retention period
• NVR recommendations: Suggests appropriate NVR models based on channel count and storage needs

No more spreadsheets, no more manual formulas — Securify calculates storage accurately every time.