This professional CCTV Storage Calculator is designed for real-world installations where not all cameras are the same.
Unlike most online calculators that assume identical cameras across the entire system, this tool allows you to:
- Create multiple camera groups
- Use different resolutions and frame rates
- Adjust compression types
- Factor in scene activity levels
- Calculate accurate storage requirements for mixed systems
How to Use This Calculator
- Enter the number of cameras in the first group
- Select the resolution, frame rate, compression, and scene activity
- Click “Add another camera group” if your system contains different camera types
- Enter your required retention period in days
- Click Calculate
The calculator will generate a detailed per-camera breakdown along with total system storage requirements and a recommended hard drive size (including safety headroom).
CCTV Storage Calculator
Understanding Each Field
Accurate storage planning depends on understanding how each setting affects recording size. Below is a detailed explanation of each input.
Number of Cameras
This is the number of cameras within a specific group that share identical recording settings.
If your installation includes:
- 6 × 4MP indoor cameras
- 2 × 8MP outdoor cameras
You should create two camera groups, not one.
Resolution (Megapixels)
Resolution directly affects bitrate and storage consumption.
Higher megapixel cameras produce more detailed images but require more storage space.
Typical impact:
- 2MP: Low storage requirement
- 4–5MP: Moderate storage requirement
- 8MP (4K): High storage requirement
- 12MP: Very high storage requirement
Doubling resolution does not exactly double storage, but it significantly increases it.
Frame Rate (FPS)
Frames Per Second (FPS) determines how many images are recorded each second.
Higher FPS increases storage linearly.
In most CCTV installations:
- 12–15 FPS is sufficient
- 20+ FPS is rarely necessary
- 25–30 FPS dramatically increases storage
For general surveillance, reducing FPS is the fastest way to extend retention.
Compression Type
Compression has a major impact on storage.
- H.264 – Older standard, larger files
- H.265 – Modern standard, significantly more efficient
- H.265+ – Enhanced optimisation (scene dependent)
Switching from H.264 to H.265 can reduce storage requirements by 30–40%.
Scene Activity Level
This factor estimates how much motion exists in the recorded scene.
- Low Activity – Warehouses, storage rooms, rarely used areas
- Typical – Offices, shops, entrances
- High Activity – Car parks, streets, busy retail
High-motion scenes generate larger bitrates due to frequent frame changes.
Outdoor cameras usually require higher storage due to lighting shifts, shadows, rain, and vehicle movement.
Retention (Days)
Retention is the number of days you want recordings stored before being overwritten.
Increasing retention multiplies storage requirements directly.
For example:
- 7 days requires half the storage of 14 days
- 30 days requires more than double 14 days
Always confirm compliance requirements before finalising retention.
How Storage Is Calculated
The calculator estimates bitrate using:
- Resolution baseline
- Frame rate scaling
- Compression efficiency
- Scene activity adjustment
It then converts:
Megabits per second → Gigabytes per day → Total Terabytes over retention period
A 25% safety margin is automatically added when recommending a hard drive size to account for:
- Scene variation
- Night-time IR noise
- Encoding differences
- Future expansion
Important Notes
- Actual storage may vary depending on camera manufacturer, firmware, GOP settings, and scene complexity.
- AI analytics, object detection, and smart encoding can increase or reduce bitrates depending on configuration.
- Always verify storage performance during commissioning.
This calculator is intended as a professional planning tool to assist installers and system designers in selecting appropriate storage capacity.