How to use the cctv storage calculator
- Enter the number of cameras and the bitrate of each in megabits per second. Find the bitrate in the camera settings.
- Enter the hours recorded per day and the days of video you want to keep.
- Open More options if cameras record only on motion, to enter the share of the time that is recorded, and to add room for overhead.
- Read the storage you need in terabytes and gigabytes, and the amount per day and per camera.
Formula
Bytes = cameras x bitrate x 1,000,000 x 3,600 x hours per day x days x recorded share / 8
With overhead: bytes x (1 + overhead %)
1 GB = 1,000,000,000 bytes and 1 TB = 1,000 GB
The bitrate is in megabits per second, and dividing by 8 turns bits into bytes. The page uses decimal units, as drive makers do. It also shows the binary TiB figure.
Eight cameras for 30 days
Eight cameras at 4 Mbps recording around the clock for 30 days use 8 x 4 x 1,000,000 x 3,600 x 24 x 30 / 8 = 10.368 TB. With 10% extra for overhead, you need 11.4048 TB, or about 11.4 TB, which is 380.2 GB a day.
If four cameras at 2.5 Mbps record only 40% of the time for 12 hours a day over 14 days, the total is 4 x 2.5 x 1,000,000 x 3,600 x 12 x 14 x 0.4 / 8 = 302.4 GB. In binary units, 11.4 TB is 10.37 TiB.
Where the bitrate comes from
Resolution, frame rate and compression decide the bitrate. A higher resolution and more frames per second raise it, and a better compression format lowers it. Cameras set to variable bitrate use more when there is a lot of movement and less in a quiet scene. The most reliable number is one from your own recorder after a few days of real use, because it reflects your scenes.
Planning the drive
Recorders overwrite the oldest video when the drive is full, so the days of video you keep is a result of the drive size, not a promise. Surveillance drives are made for constant writing. A little extra capacity gives you a margin for busy days and for the file system. Keep copies of video you need to keep, since drives can fail.
To estimate sizes for other media use the Media File Size Calculator and the Image File Size Calculator, and to size a monitor for viewing use the Screen Dimensions Calculator.
Assumptions and limits
- Every camera records at the bitrate you enter for the hours you enter.
- Motion-only recording is modeled as one constant share of the time.
- The overhead percentage is an example. Decimal units are used throughout.
- Nothing is uploaded. Calculations run in your browser.
Frequently asked questions
How much storage does one camera need?
It depends on the bitrate. A 4 Mbps camera recording all day uses 43.2 GB per day, which is about 1.3 TB for 30 days. Enter your camera's own bitrate for a real figure.
What bitrate should I use?
Use the bitrate in your camera or recorder settings. If it is variable, use the average you see after a few days. The 4 Mbps in the example is only an illustration.
Why is overhead added?
File systems and recorders use some space for their own data, and busy days use more than average days. The 10% in the page is an example, and you can change or remove it.
What is the difference between TB and TiB?
A terabyte is 1,000,000,000,000 bytes and a tebibyte is 1,099,511,627,776 bytes. Drives are sold in terabytes, while some operating systems show tebibytes under the name TB, which is why a new drive seems smaller.