CCTV Storage Calculator
The CCTV Storage Calculator estimates how much recording space a security camera system needs over a chosen retention period. Enter the number of cameras, their average recorded bitrate, the hours recorded each day, and the number of days you want to keep footage. You can also add an overhead allowance to give the estimate extra room.
For readers of thebestsecuritycameras.com, this calculator is a practical starting point when choosing storage for a DVR, NVR, or other recording system. Its result is an estimate in decimal terabytes (TB), where 1 TB equals 1,000 GB. Actual storage use depends on your cameras, recording settings, scene activity, and recorder.
What the CCTV Storage Calculator does
The calculator estimates the storage needed to retain video from cameras that share the same average bitrate and daily recording schedule. It multiplies those inputs by the retention period, converts the resulting data volume to terabytes, and applies your chosen overhead allowance.
The result, labeled Estimated Storage, helps you compare recording plans. For example, you can see how much more space you may need if you keep footage for 30 days instead of 14, or if cameras record around the clock instead of for part of each day.
The default values are illustrative assumptions, not measurements of your system. A camera’s advertised resolution alone does not tell you its average recorded bitrate. Use a bitrate from your recorder settings or a representative measurement when one is available.
How to use the CCTV Storage Calculator
- Enter the number of cameras. Count the cameras whose recordings will use the storage you are estimating. The calculator accepts whole numbers from 1 to 1,000.
- Enter the average bitrate per camera in Mbps. This is the average rate at which each camera’s recorded video generates data, measured in megabits per second. The accepted range is 0.1 to 100 Mbps.
- Enter recording hours per day. Use 24 for continuous recording, or a lower value if the cameras record for a shorter average period. The calculator accepts values from 0 to 24 hours in half-hour increments.
- Enter the retention period in days. This is how long you want to keep recordings before they are overwritten or removed. You can enter a whole number from 1 to 3,650 days.
- Enter a storage overhead allowance. Add a percentage from 0% to 100% to account for extra storage needs. The allowance is applied to the estimated video data; it is not a separate calculation of your recorder’s actual overhead.
Review the Estimated Storage result in TB. When buying drives, round up and check the usable capacity of the complete recording system. A drive’s advertised capacity may not equal the space available for recordings after formatting or other system requirements.
How the CCTV Storage Calculator formula works
The calculator multiplies the camera count and average bitrate by the total recording time, converts megabits to decimal terabytes, and then applies the overhead allowance:
Estimated Storage (TB) = Number of cameras × Average bitrate per camera (Mbps) × Recording hours per day × Retention period (days) × 3,600 ÷ 8,000,000 × (1 + Storage overhead allowance ÷ 100)
The factor 3,600 converts hours to seconds, because the bitrate is measured per second. The divisor 8,000,000 converts megabits to decimal terabytes. Finally, the overhead percentage increases the estimated video data by the amount you entered.
Worked example: four cameras for 30 days
Assume a system has four cameras, each recording at an average of 4 Mbps for 24 hours per day. The owner wants to retain footage for 30 days and chooses a 10% overhead allowance. These are the calculator’s default assumptions; a real system may use a different average bitrate.
- Number of cameras: 4
- Average bitrate per camera: 4 Mbps
- Recording hours per day: 24
- Retention period: 30 days
- Storage overhead allowance: 10%
Before overhead, the calculation is 4 × 4 × 24 × 30 × 3,600 ÷ 8,000,000 = 5.184 TB. Applying the 10% allowance gives 5.184 × 1.10 = 5.7024 TB. The calculator displays the result rounded to two decimal places: 5.70 TB.
This figure is a planning estimate, not a guarantee that a drive with exactly that advertised capacity will retain the footage for 30 days. Check recorder requirements and usable storage, then choose enough capacity to cover your needs.
Use cases for the CCTV Storage Calculator
Planning a new camera system: Estimate recording space while comparing camera counts and retention periods. This can help you identify an appropriate storage capacity before selecting a recorder and drives.
Adding cameras to an existing recorder: Enter the proposed total number of cameras to estimate the storage needed for the expanded system. If new and existing cameras use different bitrates or schedules, estimate each group separately and add the results.
Comparing retention periods: Keep the other inputs the same and change the number of days. Under the calculator’s assumptions, doubling retention time doubles the estimated video storage before overhead.
Comparing recording schedules: A business that records during a predictable part of the day can enter those daily hours and compare the result with a 24-hour schedule. For motion-triggered recording, daily hours are an assumption and may vary substantially.
Assessing bitrate changes: Compare estimates using plausible average recorded bitrates for your equipment. Higher bitrates generally require more storage for the same camera count, schedule, and retention period, but changing bitrate can also affect video quality.
Other factors to consider when calculating Estimated Storage
Variable bitrate: Many cameras change their bitrate as a scene changes. Movement, lighting, image detail, and compression settings can affect data use. The calculator uses one average bitrate for every camera, so a measured average over representative conditions is more useful than a brief reading.
Resolution, frame rate, and compression: These settings can influence bitrate, but the calculator does not calculate bitrate from them. Enter the average recorded bitrate that corresponds to the settings you plan to use. Different cameras or recording profiles may need separate estimates.
Audio and additional recording data: Audio and recorder-specific data can add to storage use. Check whether your bitrate figure includes all recorded streams, and use an appropriate overhead allowance for your planning assumptions.
Motion-triggered recording: If cameras record only when motion is detected, the average hours per day can be difficult to predict. Busy entrances, moving foliage, weather, and changes in activity may increase recording time. Consider a range of plausible daily hours when planning capacity.
Usable drive capacity and redundancy: The calculator estimates data storage, not the total advertised capacity of drives needed in a particular recorder. Formatting, system requirements, and RAID or other redundancy arrangements can reduce usable capacity. Check the recorder’s specifications and account for redundancy separately.
Retention requirements: Confirm how long you need to keep footage for your circumstances and whether your recorder overwrites old recordings automatically. Leave room for changes in camera settings or activity if maintaining the full retention period matters.
CCTV storage calculator FAQ
How much storage do four CCTV cameras need for 30 days?
At an assumed average of 4 Mbps per camera, with 24-hour recording and a 10% overhead allowance, the calculator estimates 5.70 TB. Different bitrates, recording hours, and recorder settings will produce different results.
What bitrate should I enter for a security camera?
Enter the camera’s average recorded bitrate in Mbps for the settings and conditions you expect to use. Check your recorder or camera information, or use a representative measurement if available. If cameras have substantially different bitrates, calculate their storage in separate groups.
Does the calculator account for motion recording?
It can estimate motion recording if you enter an assumed average number of recording hours per day. It does not predict when motion will occur or how activity will change bitrate, so actual use may be higher or lower.
Does the estimated storage include RAID redundancy?
No. The result estimates recording data plus the overhead percentage you enter. RAID redundancy and other reductions in usable drive capacity require separate consideration when choosing drives.
Why should I round up when buying storage?
The displayed result is rounded to two decimal places and is based on your assumptions. Actual recording use can vary, and a recorder may have less usable space than the total advertised drive capacity. Choose capacity with those factors and your desired retention period in mind.