Quick Answer+
Quick Answer: Use our calculator below to determine your exact storage needs. As a quick reference: 8 cameras at 1080p with continuous recording need ~4TB for 30 days. For 4K cameras, double or triple that estimate. Motion-only recording reduces needs by 50-70%. The most popular choice is the WD Purple 8TB (~$145), which handles most home and small business systems.
WD Purple 8TB (WD85PURZ)
8TB Capacity | 5640 RPM | 256MB Cache | CMR | 360TB/year Workload | Up to 64 Cameras | 3-Year Warranty
The sweet spot for most surveillance systems. Handles 8-12 cameras at 1080p with 30+ day retention, or 4-6 4K cameras. The 360TB/year workload rating provides reliability headroom.
Planning surveillance storage can be confusing. Too little storage means losing important footage; too much means wasting money. This calculator and guide help you determine exactly how much hard drive space your security system needs.
Surveillance Storage Calculator
Calculate Your Storage Needs
Use the reference tables below to estimate your storage requirements.
Step 1: Find Your Daily Storage Per Camera
| Resolution | Continuous (H.265) | Continuous (H.264) | Motion-Only (est.) |
|---|---|---|---|
| 720p | 8 GB/day | 12 GB/day | 2-4 GB/day |
| 1080p | 15 GB/day | 25 GB/day | 4-8 GB/day |
| 4MP (2K) | 25 GB/day | 40 GB/day | 6-12 GB/day |
| 5MP | 35 GB/day | 55 GB/day | 8-16 GB/day |
| 8MP (4K) | 50 GB/day | 80 GB/day | 12-25 GB/day |
Based on 15fps. For 30fps, double these values.
Step 2: Calculate Total Storage
Formula:Daily GB × Number of Cameras × Retention Days = Total Storage Needed
Example: 15 GB × 8 cameras × 30 days = 3,600 GB (3.6 TB)
Step 3: Add Buffer (Recommended)
Add 20-30% buffer for:
- Growth (adding cameras)
- Higher activity periods
- Drive shouldn’t run at 100% capacity
Final recommendation: 3.6 TB × 1.25 = 4.5 TB → Choose 6TB or 8TB drive
Quick Reference Tables
1080p Camera Storage Requirements
| Cameras | 7 Days | 14 Days | 30 Days | 60 Days | Recommended Drive |
|---|---|---|---|---|---|
| 2 | 210 GB | 420 GB | 900 GB | 1.8 TB | 2TB |
| 4 | 420 GB | 840 GB | 1.8 TB | 3.6 TB | 4TB |
| 6 | 630 GB | 1.3 TB | 2.7 TB | 5.4 TB | 6TB |
| 8 | 840 GB | 1.7 TB | 3.6 TB | 7.2 TB | 8TB |
| 12 | 1.3 TB | 2.5 TB | 5.4 TB | 10.8 TB | 8-12TB |
| 16 | 1.7 TB | 3.4 TB | 7.2 TB | 14.4 TB | 12-14TB |
H.265, continuous recording, 15fps
4K Camera Storage Requirements
| Cameras | 7 Days | 14 Days | 30 Days | 60 Days | Recommended Drive |
|---|---|---|---|---|---|
| 2 | 700 GB | 1.4 TB | 3 TB | 6 TB | 4-6TB |
| 4 | 1.4 TB | 2.8 TB | 6 TB | 12 TB | 8TB |
| 6 | 2.1 TB | 4.2 TB | 9 TB | 18 TB | 12TB |
| 8 | 2.8 TB | 5.6 TB | 12 TB | 24 TB | 12-14TB |
| 12 | 4.2 TB | 8.4 TB | 18 TB | 36 TB | Multiple drives |
| 16 | 5.6 TB | 11.2 TB | 24 TB | 48 TB | RAID array |
H.265, continuous recording, 15fps
Motion-Only Recording (50-70% Reduction)
| Cameras (1080p) | 30 Days (Continuous) | 30 Days (Motion-Only) | Savings |
|---|---|---|---|
| 4 | 1.8 TB | ~600 GB | 67% |
| 8 | 3.6 TB | ~1.2 TB | 67% |
| 16 | 7.2 TB | ~2.4 TB | 67% |
Motion-only savings vary based on camera location and activity level.
Factors That Affect Storage
Compression (Codec)
| Codec | Relative Size | Compatibility | Recommendation |
|---|---|---|---|
| H.264 | 100% (baseline) | Universal | Legacy systems only |
| H.265 (HEVC) | 50-60% | Most modern NVRs | Recommended |
| H.265+ / Smart codec | 30-40% | Brand-specific | Use if available |
Impact: Switching from H.264 to H.265 nearly doubles your effective storage.
Frame Rate
| Frame Rate | Storage Multiplier | Use Case |
|---|---|---|
| 10 fps | 0.67x | Low-activity areas |
| 15 fps | 1x (baseline) | Standard surveillance |
| 20 fps | 1.33x | Moderate motion |
| 30 fps | 2x | High-speed capture |
Impact: 30fps doubles storage vs 15fps. For most security purposes, 15fps is sufficient.
Recording Mode
| Mode | Storage Usage | Best For |
|---|---|---|
| Continuous | 100% | Critical areas, legal requirements |
| Motion-triggered | 30-50% | Most home/business use |
| Scheduled | Variable | Business hours only |
| Motion + continuous sub-stream | 40-60% | Balanced approach |
Resolution Details
| Marketing Name | Resolution | Megapixels | Typical Bitrate (H.265) |
|---|---|---|---|
| 720p / HD | 1280×720 | 1MP | 1-2 Mbps |
| 1080p / Full HD | 1920×1080 | 2MP | 2-4 Mbps |
| 2K / Super HD | 2560×1440 | 4MP | 4-6 Mbps |
| 5MP | 2592×1944 | 5MP | 5-8 Mbps |
| 4K / Ultra HD | 3840×2160 | 8MP | 8-15 Mbps |
Drive Recommendations by Storage Need
| Storage Needed | Recommended Drive | Price | Typical System |
|---|---|---|---|
| 1-2 TB | WD Purple 2TB | ~$59 | 2-4 cameras, motion-only |
| 2-4 TB | WD Purple 4TB | ~$79 | 4-6 cameras, mixed |
| 4-6 TB | SkyHawk 6TB | ~$109 | 6-8 cameras, continuous |
| 4-8 TB | WD Purple 8TB | ~$145 | 8 cameras, 30-day (most popular) |
| 8-10 TB | WD Purple 10TB | ~$179 | 12 cameras or 4K system |
| 10-12 TB | WD Purple 12TB | ~$199 | 8 4K cameras, 30-day |
| 12-14 TB | WD Purple 14TB | ~$249 | 16 cameras, extended retention |
| 14+ TB | WD Purple Pro 18TB | ~$380 | Large systems, AI analytics |
Common Scenarios
Home Security (4 cameras, 1080p)
- Configuration: Motion-triggered, H.265, 15fps
- Daily usage: ~20-30 GB total
- 30-day storage: ~600-900 GB
- Recommendation:WD Purple 2TB (~$59) with room to grow
Home Security (8 cameras, 1080p)
- Configuration: Continuous, H.265, 15fps
- Daily usage: ~120 GB total
- 30-day storage: ~3.6 TB
- Recommendation:WD Purple 8TB (~$145) for headroom
Small Business (8 cameras, 4K)
- Configuration: Continuous, H.265, 15fps
- Daily usage: ~400 GB total
- 30-day storage: ~12 TB
- Recommendation:WD Purple 12TB (~$199) or 14TB
Business with AI Analytics
- Configuration: 8x 4K + facial recognition
- Daily usage: ~400 GB + AI overhead
- 30-day storage: ~12-15 TB
- Recommendation:WD Purple Pro 18TB (~$380) for workload rating
Storage Optimization Tips
Maximize Your Storage
- Use H.265: Saves ~50% vs H.264
- Motion-triggered recording: Saves 50-70%
- 15fps is sufficient: Don’t use 30fps unless needed
- Adjust quality by camera: Lower resolution for non-critical areas
- Use sub-streams for live view: Reduces bandwidth without affecting recording
When to Upgrade Storage
- Retention period is too short for your needs
- Adding more cameras
- Upgrading camera resolution
- Switching from motion-only to continuous
- Drive approaching capacity (keep under 90%)
Workload Considerations
Beyond capacity, consider the drive’s workload rating:
| System Type | Annual Workload | Minimum Drive Rating |
|---|---|---|
| 4 cameras, motion-only | ~20 TB/year | Any surveillance drive |
| 8 cameras, continuous | ~45 TB/year | 180 TB/year (any) |
| 16 cameras, continuous | ~90 TB/year | 180 TB/year |
| 16 cameras, 4K continuous | ~150 TB/year | 180-360 TB/year |
| AI analytics system | 200-400 TB/year | 550 TB/year (Pro/AI drives) |
Frequently Asked Questions
For 8 cameras at 1080p with continuous recording, plan for approximately 3.6TB for 30-day retention (H.265, 15fps). We recommend an 8TB WD Purple to provide headroom for growth and ensure the drive doesn’t run at capacity.
With a single 1080p camera recording continuously (H.265, 15fps), 1TB lasts approximately 65-70 days . With motion-only recording, it can last 4-6 months . For multiple cameras, divide accordingly.
4TB is sufficient for 4-6 cameras at 1080p with 30-day retention (continuous, H.265). For 8+ cameras or 4K resolution, you’ll need more. Motion-only recording can extend 4TB to handle more cameras or longer retention.
The most effective methods: (1) Use H.265 instead of H.264 (saves ~50%), (2) Enable motion-triggered recording (saves 50-70%), (3) Use 15fps instead of 30fps (saves 50%), (4) Lower resolution for non-critical cameras.
For 16 cameras at 1080p with continuous recording and 30-day retention, you need approximately 7-8TB (H.265, 15fps). We recommend WD Purple 12TB or 14TB to provide adequate headroom. For 4K cameras, plan for 20TB+ or multiple drives.
Yes. H.265 (HEVC) typically reduces file sizes by 40-50% compared to H.264 with equivalent quality. This is significant — a system that needs 8TB with H.264 only needs 4-5TB with H.265. Most modern cameras and NVRs support H.265.
Related Guides
Drive Recommendations:
Specific Use Cases:
Comparisons:
Last updated: February 2026. Storage calculations based on typical camera bitrates and industry-standard compression.