CCTV Storage Calculator 2026
Find the exact HDD size for your NVR or DVR — enter your cameras, resolution, compression type and retention days for an instant storage result.
Based on real camera bitrates for each resolution — not generic estimates.
See exactly how much H.265 saves vs H.264 — up to 50% less storage, same quality.
Get a specific hard drive size with 20% buffer — plus brand recommendations.
Calculate for 7, 14, 30, 60, or 90 days of footage retention in one click.
CCTV Storage Calculator 2026 — How Much HDD Space Do You Need?
The storage your CCTV system needs depends on five things: number of cameras, resolution, compression codec, frame rate, and how many days of footage you want to keep. Most people dramatically overpurchase or underpurchase hard drive space because they rely on rough estimates rather than calculating from real bitrate data.
The key formula: Storage (GB) = Camera Bitrate (Mbps) × Hours of Recording × Days ÷ 8 ÷ 1,024. The biggest lever you can pull is switching from H.264 to H.265 compression — it cuts storage in half at identical image quality. Every modern IP camera and NVR made after 2019 supports H.265.
CCTV Storage Requirements by Resolution and Retention
| Resolution | Codec | Per Camera / Day | 4 Cameras / 30 Days | 8 Cameras / 30 Days |
|---|---|---|---|---|
| 1080p (2MP) | H.264 | 21.1 GB | 2.5 TB | 5.0 TB |
| 1080p (2MP) | H.265 | 10.5 GB | 1.3 TB | 2.5 TB |
| 2K / 4MP | H.264 | 42.2 GB | 5.0 TB | 10.0 TB |
| 2K / 4MP | H.265 | 21.1 GB | 2.5 TB | 5.0 TB |
| 4K / 8MP | H.264 | 84.4 GB | 10.1 TB | 20.2 TB |
| 4K / 8MP | H.265 | 42.2 GB | 5.0 TB | 10.1 TB |
Which HDD Should You Use in an NVR or DVR?
Never use a standard desktop hard drive in a security camera system. Desktop HDDs are designed for intermittent read/write workloads — they fail quickly under the continuous 24/7 write cycles of a CCTV system. Surveillance-grade drives are built specifically for this:
The Seagate SkyHawk series (1TB–20TB) is the most widely used NVR HDD in 2026, featuring AllFrame technology that reduces dropped frames during simultaneous write from multiple cameras. The Western Digital Purple series is the main alternative, with WD Purple Pro supporting up to 32 AI-based cameras for systems with video analytics. For budget builds, the Toshiba S300 is a reliable third option available in 1TB–8TB capacities.
Always add at least 20% buffer headroom to your calculated storage — this is already included in the HDD recommendation from the calculator above. A drive that runs at 95%+ capacity degrades write performance and increases failure risk.
How to Reduce CCTV Storage Without Losing Quality
Switch to H.265 compression first — it saves 50% storage with zero quality difference on any modern NVR. Next, use motion-triggered or scheduled recording instead of continuous 24/7 if your use case allows it; motion-only recording typically uses 20–30% of the storage that continuous recording needs. For 4K cameras, enabling H.265+ (smart codec) on Hikvision or Dahua NVRs further reduces bitrate by 50–75% during low-activity scenes. You can also pair your home security system with a strong WiFi mesh network to support wireless IP cameras without dropped frames.
CCTV Storage Calculator — Frequently Asked Questions
Results are estimates based on standard camera bitrate values. Actual storage varies by camera brand, NVR firmware, scene complexity, and motion frequency. Always add a 20% buffer — already included in the HDD recommendation above.