Security Camera Footage Backup Time Calculator
What the Security Camera Footage Backup Time Calculator does
The Security Camera Footage Backup Time Calculator estimates how many days of continuous security camera footage can fit in the storage you have available. It combines your backup storage capacity, number of cameras, average bitrate per camera, and the percentage of storage available for footage.
The result, labeled Estimated retention, is shown in days. For example, the calculator’s default settings estimate that 1,728 GB of backup storage can hold 6.40 days of footage from four cameras recording continuously at an average of 5 Mbps each, when 80% of the storage is available for footage.
This estimate can help you plan a backup drive, compare recording settings, or understand whether your existing storage is likely to meet your retention goal. It estimates how long footage can be retained; it does not calculate how long a backup transfer will take.
How to use the Security Camera Footage Backup Time Calculator
Enter the following four values to estimate your footage retention:
- Backup storage capacity (GB): Enter the total capacity of the storage you plan to use for footage, expressed in gigabytes. You can use the capacity of a dedicated backup drive or the space assigned to camera recordings on a larger storage system.
- Number of cameras: Enter the number of cameras whose footage will be stored. The calculation assumes every camera records continuously at the average bitrate you enter.
- Average bitrate per camera (Mbps): Enter the average recording bitrate for each camera in megabits per second. Check your camera or recorder settings for a useful starting point. If cameras use different bitrates, use their average.
- Storage available for footage (%): Enter the percentage of the stated storage capacity that footage can use. This lets you account for reserved space, other files, and storage overhead.
Read the result as an estimate of the number of days the available space can hold at those settings. If you want to compare scenarios, change one input at a time. For example, you can see how adding cameras or increasing storage capacity changes the estimated retention.
Tip: Use the bitrate of the recorded stream, which may differ from the bitrate of a live preview or a lower-quality secondary stream. If audio is stored with the footage, make sure your bitrate estimate accounts for it where possible.
How the Security Camera Footage Backup Time Calculator formula works
The calculation divides usable storage by the combined recording rate of all cameras. It uses decimal storage units: 1 GB equals 8,000 megabits, and one day contains 86,400 seconds.
Estimated retention in days = (storage capacity in GB × 8,000 × storage available for footage ÷ 100) ÷ (number of cameras × bitrate per camera in Mbps × 86,400)
The percentage converts total capacity into usable capacity. The camera count and bitrate give the combined recording rate, while the number of seconds in a day converts that rate into daily storage use.
Worked example using the default settings
Suppose you have 1,728 GB of backup storage, four cameras, and an assumed average bitrate of 5 Mbps per camera. You expect 80% of the storage to be available for footage.
- Usable storage: 1,728 GB × 80% = 1,382.4 GB.
- Combined camera bitrate: 4 × 5 Mbps = 20 Mbps.
- Estimated footage stored per day: 20 Mbps × 86,400 seconds ÷ 8,000 = 216 GB per day.
- Estimated retention: 1,382.4 GB ÷ 216 GB per day = 6.40 days.
The 5 Mbps bitrate and 80% usable capacity are illustrative assumptions. Your cameras and storage system may use different values, so replace them with figures that reflect your setup.
Use cases for the Security Camera Footage Backup Time Calculator
Planning a backup drive: If you know how many days of footage you want to keep, you can try different storage capacities to see which one produces an estimated retention close to your goal. Leave room for overhead and changes in recording activity.
Adding security cameras: More cameras generate more footage. If all other inputs stay the same, increasing the camera count reduces retention. For instance, doubling the number of cameras at the same average bitrate halves the estimated number of days.
Comparing recording settings: Higher image quality can require a higher bitrate and more storage. Enter different assumed average bitrates to see how much retention might change before adjusting your camera settings.
Checking an existing system: Enter the capacity and recording details of your current setup to get a baseline estimate. Compare it with the retention you actually observe over time. A difference may indicate that your average bitrate, usable storage percentage, or recording schedule needs a closer look.
Allowing for shared storage: If other files or applications use the same drive, the storage available for footage percentage helps you estimate the portion left for recordings. For example, entering 70% assumes that 30% of the stated capacity is unavailable for footage.
Other factors to consider when calculating Estimated retention
Variable bitrate: Many cameras do not record at a perfectly steady rate. Movement, lighting changes, image detail, and compression settings can affect the bitrate. A busy entrance or a scene with moving trees may use more data than a quiet indoor view. An average measured over representative conditions can make your estimate more useful.
Recording schedule: The calculator assumes continuous recording from every camera. Motion-triggered or scheduled recording may use less storage, but the actual amount depends on how often recording occurs and how long each event lasts. The result is therefore a continuous-recording baseline for those systems.
Resolution, frame rate, and compression: These settings affect image quality and storage use through the resulting bitrate. Two cameras with the same advertised resolution can use different amounts of storage if their frame rates, compression formats, or quality settings differ.
Different camera settings: The calculator applies one average bitrate to every camera. If your cameras record at different rates, add their average bitrates and divide by the number of cameras to find the figure to enter. Make sure those averages reflect the streams you intend to back up.
Audio and storage overhead: Audio can add to recording data. Indexes, system files, reserved space, and other content can also reduce the capacity available for video. Use the footage percentage to account for space that recordings cannot use.
Decimal and binary capacity: This calculator treats 1 GB as 8,000 megabits. Some devices report storage using binary units, which can make the capacity displayed by the device differ from a drive’s decimal GB figure. Check which unit your device reports when entering capacity.
Retention behavior: A recorder or backup system may overwrite older footage when storage fills, stop recording, or follow a configured retention policy. The calculator estimates capacity-based retention; check your system’s settings to understand what happens when it reaches its limit.
Frequently asked questions
How much storage does a security camera use per day?
It depends on the camera’s average recording bitrate. As an illustrative example, one camera recording continuously at an assumed 5 Mbps uses approximately 54 GB per day under the calculator’s decimal-unit convention. Actual use can change with motion, compression, audio, and recording settings.
How do I find the average bitrate per camera?
Look in your camera, network video recorder, or recording software settings for the bitrate of the stream being saved. If the system uses variable bitrate, a measured average over a representative period is more useful than assuming the rate remains fixed. Include audio in your estimate where applicable.
Can I use the calculator for motion-triggered recording?
You can use it as a continuous-recording baseline, but it does not include a control for recording schedules or event frequency. Motion-triggered footage may last longer in the available storage, depending on how much activity the cameras capture.
Why is my actual retention different from the estimate?
Your actual average bitrate may differ from the value entered, or less storage may be available for footage than expected. Variable motion, audio, different camera settings, storage overhead, and the system’s overwrite or retention policy can all affect the result.
Does this calculator show how long a backup transfer takes?
No. It estimates how many days of continuous footage can fit in the available storage. Transfer time depends on factors such as the amount of data being copied and the speed of the network, source device, and destination drive.