CCTV Storage Calculator
Free tool to calculate exactly how much HDD storage your NVR needs — by camera count, resolution (1080p to 4K), codec (H.264, H.265, H.265+), frame rate, motion detection, RAID, and retention period.
How to Calculate CCTV Storage Requirements
CCTV storage requirements depend on five key variables: number of cameras, video resolution, codec/compression, frame rate, and retention period. The formula is:
Resolution & Codec
Resolution determines raw pixel count; the codec compresses it. H.265 uses ~50% less storage than H.264 at the same quality. H.265+ (Hikvision) and WiseStream II (Hanwha) go even further — up to 75% reduction vs. H.264.
Frame Rate
30 fps delivers smooth video but doubles storage vs. 15 fps. For most security applications, 15 fps is ideal — it's smooth enough to identify faces and license plates while significantly reducing storage. ATMs and cash registers benefit from 25–30 fps.
Motion Detection
Cameras recording only on motion (at typical 30% activity) use roughly 37% of the storage of continuous recording. Our calculator models the idle bitrate (~7%) to give a realistic estimate — not the misleading assumption of zero storage between events.
Retention Period
Most businesses need 30 days. Banking and healthcare commonly require 90 days. The longer the retention, the larger the drive needed — or the more frequently footage overwrites. RAID redundancy adds a multiplier to the raw drive capacity needed.
Security Camera Bitrate & Storage Reference Table
Approximate bitrates at 25 fps (peak). H.265+ = Hikvision's proprietary codec. WiseStream II = Hanwha Wisenet. Storage per camera per day at 24h continuous recording.
| Resolution | H.264 Mbps | H.265 Mbps | H.265+ Mbps | WiseStream II Mbps | H.265 GB/cam/day |
|---|---|---|---|---|---|
| 720p (HD) | 1.5 | 0.75 | 0.4 | 0.3 | 7.9 |
| 1080p (FHD) | 4.0 | 2.0 | 1.0 | 0.7 | 21.1 |
| 4MP | 6.0 | 3.0 | 1.5 | 1.0 | 31.6 |
| 4K (8MP) | 12.0 | 6.0 | 3.0 | 2.0 | 63.3 |
| 12MP | 18.0 | 9.0 | 4.5 | 3.0 | 94.9 |
* Bitrates are at 25 fps. Storage estimates scale linearly with frame rate. Actual bitrates vary by scene activity and camera model.
4 cameras, 1080p, H.265, 30 days
~650 GB
2 TB drive8 cameras, 1080p, H.265, 30 days
~1.3 TB
2–4 TB drive16 cameras, 4K, H.265, 30 days
~9.3 TB
12 TB+ or multi-driveRecommended Retention Periods by Industry
How long footage must be kept varies by industry, jurisdiction, and insurance requirements. These are common US benchmarks.
| Industry / Use Case | Retention |
|---|---|
| Retail / Shop | 30 days |
| Office / Commercial | 30–60 days |
| Warehouse / Logistics | 30 days |
| Banking / Finance | 90 days |
| Healthcare / Hospital | 90–180 days |
| Government Facility | 90–365 days |
| Residential | 7–14 days |
| School / Education | 30–60 days |
| Hotel / Hospitality | 30 days |
| Construction Site | 30–90 days |
Shop Storage & Recorders at Wholesale Pricing
WD Purple Surveillance Drives
24/7-rated, NVR-optimized. 1 TB – 12 TB in stock.
Hikvision NVRs
4ch to 64ch NVRs with built-in PoE, H.265+ and AI deep learning.
Hanwha WAVE Servers
Pre-built WAVE VMS appliances. 8 TB and 16 TB with 4 Pro licenses.
Need a custom quote for your CCTV system? Contact IDS CCTV →
FAQ
CCTV Storage — Frequently Asked Questions
Common questions about how much storage you need for security cameras and NVRs.
How much storage do I need for 4 security cameras?+
For 4 cameras at 1080p, 15 fps, H.265, recording 24/7 for 30 days you need approximately 650 GB – 1 TB. With motion detection at ~30% activity, that drops to around 200–300 GB. A 2 TB WD Purple drive comfortably covers a 4-camera system with 30+ days retention.
How much storage do I need for 8 security cameras?+
An 8-camera system at 1080p, 15 fps, H.265 continuous recording requires roughly 1.3–2 TB for 30 days. With motion detection at typical activity (30%), around 400–600 GB. A 4 TB WD Purple drive is the standard recommendation for an 8-channel 1080p NVR.
How much storage do I need for 16 cameras?+
16 cameras at 1080p, H.265, 15 fps continuous need around 2.5–4 TB for 30 days. A 4K (8MP) 16-camera system needs 5–10 TB. For large systems, 8 TB drives or multi-drive NVRs with 4–8 bays are typically used.
How long does 1 TB last on a security camera NVR?+
At 1080p H.265, 15 fps, continuous recording: 1 TB lasts approximately 7 days for 4 cameras, or 3–4 days for 8 cameras. With motion detection at 30% activity, 1 TB covers 20–25 days for 4 cameras. Use the calculator above for your exact configuration.
How long does a 4 TB NVR record for?+
A 4 TB NVR at 1080p H.265 15 fps continuous: approximately 28 days for 4 cameras, or 14 days for 8 cameras. With H.265+ and motion detection, a 4 TB drive can cover 60+ days for a 4-camera system. For 4K cameras, expect roughly half the duration.
What is the difference between H.264 and H.265 for CCTV storage?+
H.265 (HEVC) compresses video approximately 50% more efficiently than H.264, halving storage and bandwidth requirements at the same quality. H.265+ (used by Hikvision and Dahua) goes further — typically 50–75% smaller than H.264. Most modern NVRs from Hikvision, Hanwha, and Uniview support H.265 or H.265+.
How much does motion detection reduce CCTV storage?+
Motion detection recording can reduce storage by 50–80% compared to continuous recording. A typical commercial environment with 30% motion activity uses about 37% of continuous-recording storage (cameras idle at ~7% bitrate between events). A retail store or warehouse entrance with 60% activity still saves 35–40% vs. continuous.
What resolution should I choose for my security cameras?+
1080p (2MP) is the minimum recommended for most applications and balances storage with image clarity. 4MP gives noticeably better detail for license plate or face recognition at wider angles. 4K (8MP) is best for large open areas where digital zoom-in is required, but needs 4× the storage of 1080p. Most professional installers use 4MP or 4K for perimeter cameras and 1080p for interior coverage.
What frame rate should I use for security cameras?+
15 fps is the industry standard for most security applications — smooth enough for identification while using half the storage of 30 fps. For high-traffic areas (cash registers, ATMs, turnstiles) or license plate capture, 25–30 fps is preferred. For long-term archival or low-activity areas, 5–10 fps significantly reduces storage.
How much storage does a 4K security camera use?+
A single 4K (8MP) camera recording at 15 fps H.265 uses approximately 2–3 Mbps, or about 22–32 GB per day. With H.265+ or WiseStream compression, this drops to 1–1.5 Mbps (11–16 GB/day). For a 30-day 4-camera 4K system with H.265, plan for approximately 2.5–4 TB.
What is a good retention period for security cameras?+
Most businesses use 30 days as the standard retention period. Retail and banking often require 60–90 days. Government and healthcare facilities may require 90–180 days. For incident investigation, 7–14 days is often enough, but 30 days is the safe default that balances storage cost with adequate coverage.
Does adding audio recording significantly increase storage?+
Audio recording (G.711, 64 kbps per channel) adds approximately 0.7 GB per camera per day — minimal compared to video. For an 8-camera system running 24/7 for 30 days, audio adds roughly 16 GB total, which is less than 1% of typical video storage. Most NVRs support audio with minimal impact.
What size WD Purple drive should I buy for my NVR?+
WD Purple drives are purpose-built for surveillance with 24/7 write optimization. For a 4-camera 1080p system with 30-day retention, a 2 TB WD Purple is sufficient. For 8 cameras or 4K resolution, choose 4–8 TB. For large systems with 16+ cameras or extended retention, 8–12 TB drives or multiple drives are recommended. IDS CCTV stocks WD Purple surveillance drives at wholesale pricing.