CCTV Storage Calculator UK: How Many Days Do You Need?

Calculating CCTV storage requirements is essential to ensure you don't run out of space before an incident is discovered. The total storage needed depends on four primary factors: resolution (4MP vs 4K), frame rate (frames per second, or fps), compression codec (H.264 vs H.265+), and recording schedule (continuous vs motion-detection).

Understanding the Variables of CCTV Storage

A higher resolution captures more detail but generates larger file sizes. For home security, recording at 15fps provides smooth, fluid video while saving substantial hard drive space compared to television-standard 25fps or 30fps.

H.265+ Compression: The Ultimate Storage Saver

Video compression is the most critical factor in storage management. The older H.264 standard is highly inefficient for high-resolution video. The newer H.265 (HEVC) standard halves the bandwidth and storage required.

Commercial brands like Hikvision have developed H.265+, an advanced smart codec that analyses static backgrounds and only records pixels that are actively moving. H.265+ reduces storage consumption by up to 70% compared to standard H.265, allowing you to store weeks of 4K footage on modest hard drives.

Choosing between 24/7 Continuous and Motion Recording

Continuous recording guarantees you never miss a thing, but it consumes space rapidly. Motion-only recording saves space by only writing to the hard drive when the camera detects movement. However, older motion detection is easily fooled by trees and rain, creating useless empty files.

In 2026, NVRs use AI-powered detection (like Hikvision AcuSense) to ignore environmental motion and only record when humans or vehicles are present. This 'smart motion' recording is highly reliable and can increase storage retention by 300%.

Selecting a Surveillance-Grade Hard Drive

Never use standard desktop computer hard drives in a CCTV NVR. NVRs write data continuously 24 hours a day, generating high heat and mechanical stress. Standard drives will fail within a few months.

Instead, use dedicated surveillance-grade drives, such as Western Digital Purple or Seagate SkyHawk. These drives are designed specifically for write-intensive workloads, support multi-drive RAID setups, and include firmware optimized to prevent frame loss.

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CCTV Storage Calculator UK Comparison