NVR Storage Calculator
Choosing the right hard drive capacity is an important part of planning a security camera system. If your NVR runs out of space before the end of your desired retention period, it may overwrite recordings sooner than you expect. The NVR Storage Calculator estimates how much space your cameras need based on their average bitrate, recording schedule, retention period, and an extra storage allowance.
The result is shown in decimal terabytes (TB), where 1 TB equals 1,000 GB. Use it as a starting point when comparing NVR storage options, then round up to enough usable drive capacity for your setup.
What the NVR Storage Calculator does
The NVR Storage Calculator estimates the recording capacity needed for a group of security cameras. It combines the number of cameras with an assumed average bitrate per camera and the amount of time each camera records. It then extends that estimate across your chosen retention period and adds your extra storage allowance.
For example, a system that records eight cameras around the clock will generally need more storage than the same system recording only a few hours per day. Increasing the average bitrate or keeping footage for more days also increases the estimated capacity.
The calculator assumes that every camera uses the same average bitrate and daily recording schedule. If your cameras use different settings, you can estimate groups separately and add their results. The result is an estimate of recording storage, so the usable capacity of your NVR and its drives should be checked before you buy.
How to use the NVR Storage Calculator
Enter the following information to estimate your security camera storage needs:
- Number of cameras: Enter the number of cameras whose recordings you want to store. The calculator accepts whole numbers from 1 to 1,024.
- Average bitrate per camera (Mbps): Enter the average recording bitrate for each camera in megabits per second. You can use a value from 0.1 to 100 Mbps. Check your camera or NVR settings for a useful starting point.
- Recording time (hours per day): Enter the average number of hours each camera records daily, from 0 to 24. Use 24 for continuous recording or an estimated daily average for a recording schedule.
- Retention period (days): Enter how many days of footage you want to retain, from 1 to 3,650 days.
- Extra storage allowance (%): Add an allowance from 0% to 100% for uncertainty and other storage needs that apply to your system.
The Estimated storage result is displayed in TB to two decimal places. When purchasing drives, round up to a configuration with enough usable capacity rather than choosing a capacity that only matches the displayed estimate.
For motion-based recording, daily recording time is an assumption. One quiet day may produce much less footage than a busy day, so consider a representative average and leave room for variation.
How the NVR Storage Calculator formula works
The formula estimates the data generated by the cameras over the recording period, converts that data to decimal terabytes, and applies the extra storage allowance:
Estimated storage (TB) = Number of cameras × Average bitrate per camera (Mbps) × Recording time (hours per day) × Retention period (days) × 3,600 ÷ 8,000,000 × (1 + Extra storage allowance ÷ 100)
The 3,600 converts hours to seconds. The divisor converts the data rate from megabits per second into decimal terabytes over the recording period. Finally, the allowance increases the estimate by the percentage you entered.
Consider this example using the calculator’s default values. The 4 Mbps average bitrate and 10% allowance are illustrative assumptions; your system may need different values.
- Number of cameras: 8
- Average bitrate per camera: 4 Mbps
- Recording time: 24 hours per day
- Retention period: 30 days
- Extra storage allowance: 10%
Before the allowance, the calculation is 8 × 4 × 24 × 30 × 3,600 ÷ 8,000,000, or 10.368 TB. Applying the 10% allowance gives 10.368 × 1.10 = 11.4048 TB. The calculator displays this as 11.40 TB.
This example shows estimated data storage, not a guarantee that a particular drive configuration will retain footage for exactly 30 days. Confirm the usable capacity and recording behavior of your NVR before selecting drives.
Use cases for the NVR Storage Calculator
Planning a home security system: Estimate how much recording space you may need for cameras covering entrances, a driveway, and other areas. Compare continuous recording with a shorter average recording schedule to see how the choice affects capacity.
Estimating storage for a business: A shop, office, or warehouse may have more cameras and a longer retention target. Enter the planned camera count and recording period to establish a storage estimate before choosing an NVR and drives.
Adding cameras to an existing NVR: Calculate the estimated storage for the expanded camera count, then compare it with the usable space available in your current system. Also check whether the NVR supports the additional cameras and drive capacity.
Comparing retention periods: Run the calculation with different day values to understand how long footage can be kept. If the camera count, bitrate, and recording hours stay the same, doubling the retention period doubles the estimate before the allowance.
Estimating camera groups with different settings: If some cameras record at a different average bitrate or for different hours, calculate each group separately and add the displayed estimates. For greater precision when totals are close to a drive capacity limit, leave extra room because each displayed group result is rounded to two decimal places.
Other factors to consider when calculating Estimated storage
Variable bitrate and scene activity: Some cameras change their bitrate as scene detail and movement change. A busy street, moving foliage, rain, or nighttime image noise can affect the amount of data recorded. A bitrate observed during a quiet period may not represent the long-term average.
Compression and camera settings: The selected compression method, resolution, frame rate, image quality, and bitrate settings can all affect storage. Use the expected average recording bitrate for the configuration you intend to run, rather than assuming that every camera with the same resolution uses the same amount of space.
Audio and additional recordings: Audio and other recorded data can add to storage requirements. Check whether the bitrate you enter reflects the recording streams you plan to keep, and consider these needs when setting your allowance.
Motion-based recording: The recording time field represents an average number of hours per day. Actual motion events may vary considerably, so a low average can underestimate the space needed during an unusually active period.
Usable drive capacity: The estimate uses decimal TB, but the capacity available for recordings can differ from a drive’s advertised capacity. Formatting and filesystem overhead can reduce usable space. If your system uses RAID, its usable capacity depends on the configuration and may be less than the combined capacity of its drives. The calculator does not automatically account for these factors; assess them for your setup and include an appropriate allowance where needed.
Overwrite settings: Many NVRs can overwrite older footage when storage fills. Check your NVR’s settings and monitor actual retention after installation. If recordings disappear sooner than required, adjust your recording settings or add sufficient supported storage.
NVR storage FAQ
How much storage do I need for eight security cameras?
It depends on the cameras’ average bitrate, how long they record each day, and how long you retain footage. As an illustrative example, eight cameras averaging 4 Mbps each, recording 24 hours a day for 30 days with a 10% allowance, need an estimated 11.40 TB. Your actual requirements may be higher or lower.
What bitrate should I enter for my security cameras?
Enter the expected average recording bitrate per camera in Mbps. Your camera or NVR settings can provide a starting point, but actual averages may change with scene activity, compression, and recording settings. If camera groups have substantially different averages, estimate them separately.
Does motion recording always use less storage than continuous recording?
It can use less storage when cameras record for fewer hours, but the saving depends on how often motion triggers recording and how long each event lasts. Use an estimated daily average that reflects your location and allow for busy periods.
Does the calculator include RAID and drive formatting?
No. RAID capacity, drive formatting, and filesystem overhead are not calculated automatically. Check the usable capacity of your intended NVR configuration and choose an extra storage allowance appropriate for your needs.
Why should I round up when buying NVR drives?
The displayed result is an estimate rounded to two decimal places, and real recording rates can vary. Rounding up to sufficient usable capacity gives your system room for those differences and helps support your desired retention period.