Security System Tool

DVR Time Calculator

Estimate your CCTV recording retention time. Calculate days of storage based on Hard Drive size, Camera resolution, Codec (H.265+), and FPS.

System Specs

Cams
H.264

Old Standard

H.265

High Efficiency

H.265+

Ultra Smart

Adjust for Motion Detection (e.g., 8-12 hours per day approx).

Estimate Ready?

Enter drive size and camera specs to see how long you can record.

DVR Time Calculator: The Ultimate CCTV Storage Guide (2025)

When installing a CCTV system, one of the most critical questions is: "How long will my security footage last before it gets overwritten?" Choosing the wrong hard drive size can mean losing critical evidence just when you need it most.

Our DVR Time Calculator (also known as a CCTV Storage Calculator) is designed to help security professionals and homeowners estimate recording retention. Whether you are using an analog DVR or a modern 4K NVR with H.265+ compression, this tool provides precise calculations to help you select the right HDD capacity.

Key Factors Affecting Recording Time

Video storage isn't just about the size of your hard drive (1TB, 2TB, etc.). It depends on how much data your cameras are pushing every second.

1. Resolution (Megapixels)

Higher resolution means sharper images but significantly more data.
1080p (2MP): The industry standard. Good balance of quality and storage.
4K (8MP): Offers 4x the detail of 1080p but consumes roughly 3-4x the storage space.

2. Video Compression (Codec)

This is the technology that shrinks video files.
H.264: Older standard. Less efficient.
H.265 (HEVC): Saves about 40-50% storage compared to H.264.
H.265+: Smart coding used by brands like Hikvision/Dahua. Can save up to 70-80% storage by ignoring static backgrounds.

3. Frame Rate (FPS)

Movies look smooth at 24fps or 30fps. Security cameras don't always need that.
30fps: Real-time smooth motion. High storage use.
15fps: Standard for security. Motion looks fine, saves 50% storage vs 30fps.
7fps: Choppy but usable for evidence. Saves massive space.

4. Recording Mode

  • Continuous (24/7): Records everything, even empty rooms. Uses max storage.
  • Motion Detection: Only records when pixels change. In a typical home, this might only be 2-4 hours of footage per day, extending your hard drive life by 5x or more.

How to Choose the Right Hard Drive (HDD)

Not all hard drives are built for CCTV. Regular PC drives (desktop HDDs) are designed to run for 8 hours a day. Surveillance HDDs (like WD Purple or Seagate SkyHawk) are built for 24/7 operation.

Recommended Sizes:
4 Camera System (1080p): 1TB - 2TB for 2 weeks retention.
8 Camera System (4K): 4TB - 8TB for 2 weeks retention.
Business Requirement: Many insurance policies require 30 days of footage. Always calculate for 30 days minimum for commercial use.

Frequently Asked Questions (FAQ)

Does lowering FPS affect quality? ▼

It affects the smoothness of motion, not the clarity of a single frame (like a license plate). For most security needs, 15fps is perfectly adequate. 30fps is overkill unless you are monitoring a casino or fast traffic.

What is Bitrate? ▼

Bitrate (measured in kbps or Mbps) is the amount of data processed per second. Higher bitrate = better quality but more storage usage. Our calculator estimates the standard bitrate for each resolution automatically.

What happens when the HDD is full? ▼

Modern DVRs and NVRs are set to "Overwrite." This means they delete the oldest footage automatically to make room for new video. If your calculator says "14 Days," it means on Day 15, Day 1 gets deleted.

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