Many CCTV systems run out of space within days, because the buyer bought disks by guess. A CCTV storage calculator gives the real number before you order. This guide gives the formula, a worked example and ways to reduce the total.
The formula
Take the bitrate in megabits per second and multiply it by 86,400 seconds in a day. Divide by eight to convert bits to bytes, then by 1,000 to reach gigabytes. That gives the storage for one camera per day.
In short: bitrate in Mbps multiplied by 10.8 gives gigabytes per day. Multiply by the number of cameras and the number of days.
A worked example
A camera streaming at 4 Mbps records about 43.2 GB each day. Sixteen cameras recording for 30 days need 43.2 x 16 x 30, which is 20,736 GB, or about 20.7 TB. At 8 Mbps the figure doubles; at 2 Mbps it halves.
What sets the bitrate
Bitrate depends on resolution, frame rate, compression and the scene. A busy road scene with many moving objects needs more than a quiet corridor. Higher resolution and more frames per second raise the rate.
H.265 compression often needs less bitrate than H.264 for similar quality, though results depend on the camera.
Ways to reduce storage
Record on motion only in quiet areas, lower the frame rate where speed does not matter and use sub-streams for live view. Keep high quality for entrances and cash counters.
Do not cut bitrate so far that faces and number plates blur. Our IP camera installation page explains how we set cameras.
Extra space to plan for
RAID protects against a disk failure but uses part of the capacity. Leave spare room for new cameras and for the loss of a drive. Choose surveillance-grade disks, since ordinary disks fail early under constant writing. Our NVR guide shows recorders for large systems.
Mistakes to avoid
When people use a CCTV storage calculator they often go wrong in these ways.
- Using the camera's top bitrate for every camera, which wastes disk space
- Using the lowest bitrate, so that recordings are too short
- Forgetting the space lost to RAID and spare disks
- Buying ordinary disks instead of surveillance-grade disks
- Ignoring growth, so a new camera forces a new recorder
Your next step
Send us the number of cameras, the resolution and the days of recording you want. We will size the disks and give you the working in writing. Essatech designs, supplies, installs and services these systems in Hyderabad and Visakhapatnam. Send us your drawings or photos for a priced plan.
What affects the price
- Number of cameras and resolution
- Days of recording needed
- Continuous or motion recording
- RAID level and spare disks
- Recorder or server type
- Backup and archive needs
What to send us
- Number of cameras and resolution
- Days of recording needed
- Areas that need continuous recording
- Any existing recorder