How Much Storage Does Your Security Camera Need?

A security camera can record 24/7 and still have a surprisingly short memory. Before you buy a card or drive, estimate how much footage your settings will produce—and leave room for the stuff a simple calculator misses.

Quick answer: Find your camera's actual average recording bitrate, enter it along with your camera count, recording schedule and desired retention in the openWorkstand CCTV Storage Calculator, and treat the result as a starting estimate. Check the device's supported card or drive capacity before buying.

We tested the calculator with sample numbers for this guide. We did not test a security camera, card, or recorder.

1. Gather the numbers

Look in your camera or recorder's current settings or documentation for its recording bitrate, usually shown in Mbps or Mbit/s. Use a measured average if available: a variable bitrate changes with scene activity and conditions. Don't substitute your internet speed for the video bitrate.

Decide how many cameras save to the same storage, how many days of footage you want, and how many hours a day they record. If they record only on motion, estimate what percentage of those hours contains footage. A rough guess can be very wrong on a busy street or with frequent false triggers.

2. Run a sample estimate

Open the calculator. Under Starting point, choose Enter the bitrate myself when you know your camera's rate; otherwise pick a preset as an example, not a promise. Enter the number of cameras, days to keep, recording hours per day, and the share of time actually recorded.

The openWorkstand calculator showing our sample inputs and result. Screenshot captured by TRT; interface: openWorkstand.

For a worked example, we selected the 2 Mbit/s preset and entered one camera, seven days, 24 hours per day and 100% recording. The calculator displayed 21.6 GB per camera per day and 0.15 TB total, or about 151.2 GB before rounding. Its 20% headroom line displayed 0.18 TB. Those are decimal storage units; the tool also displays the binary TiB equivalent. The calculator's own explanation describes the bitrate math and limitations.

Try changing just one input at a time. Doubling the number of otherwise identical cameras doubles the estimated storage. Changing recording hours or motion share changes the result too. For cameras with different bitrates or recording schedules, estimate each group separately and add the results.

3. Choose storage with a margin

The number on screen is a planning estimate, not a guaranteed retention period. The calculator says its base estimate does not include audio and overhead unless you add them to the bitrate. File-system space, thumbnails, recorder features and redundancy can also consume capacity. Its 20% headroom line is a useful starting allowance, not a guarantee that every system's overhead is covered.

Check your camera or recorder's supported card types, maximum capacity, file-system requirements, and the manufacturer's recommendation for sustained recording before purchasing. A card that is large enough on paper still needs to be supported by the device. For a recorder with redundant drives, account separately for the usable capacity of the array.

4. Check what your setup actually keeps

After setup, check your recorder's oldest available footage after it has run long enough to fill its storage. Review a few busy and quiet days and adjust the estimate if actual use differs. Before changing overwrite or retention settings, read your device's instructions; behavior differs between models.

Motion-only storage can stretch capacity, but it only saves the events your camera actually detects. Test detection and playback for the places and times you care about, and check any continuous or pre-event recordings separately. A calculator cannot tell you whether a particular incident will be captured.

How we checked: We entered the example above into openWorkstand's browser calculator and inspected its result. We independently checked the arithmetic. We did not install or configure a camera or verify real-world retention. Interface and featured screenshot: openWorkstand, captured by TRT.