Video Recording Time Calculator
Knowing how long a security camera can record helps you choose storage capacity and plan how much footage you can keep. The Video Recording Time Calculator estimates continuous recording time from the storage space available and the combined video and audio bitrates of your cameras.
Enter your storage capacity, the percentage available for recordings, your bitrates, and an allowance for recording overhead. The result appears in hours. Use it as a planning estimate: actual recording time can change as camera activity, bitrate, storage use, and system settings change.
What the Video Recording Time Calculator does
The calculator estimates how long available storage can hold a continuous video recording at the average bitrates you enter. It can be used for a single camera or for a system with multiple cameras recording to the same storage device.
For example, you might use it to estimate how long footage can be stored on a security camera recorder, a dedicated hard drive, or a memory card. If several cameras share the storage, add their video bitrates together and enter the total. Do the same for audio if it is recorded.
The calculation assumes that recording continues at the entered average bitrate. It does not predict exactly when old footage will be overwritten or guarantee that a particular number of days of footage will be available.
How to use the Video Recording Time Calculator
- Enter Storage capacity (GB). This is the total capacity of the drive, memory card, or other storage space you are assessing. The calculator uses decimal gigabytes, where 1 GB equals 1,000 MB.
- Enter Storage available for recordings (%). Use the percentage of that capacity you expect to be available for footage. If all of it is available, enter 100%. If other files or system functions use some space, enter a lower percentage.
- Enter Combined video bitrate (Mbps). Enter the average video bitrate in megabits per second. For multiple cameras sharing the storage, add their average video bitrates and enter the combined figure.
- Enter Combined audio bitrate (Mbps). Add the average audio bitrates for all relevant recordings. Enter 0 if no audio is recorded.
- Enter Recording overhead (%). Add an assumed percentage for recording-related data beyond the entered video and audio bitrates. The appropriate allowance depends on the system and recording format.
- Review Recording Time. The result is displayed in hours to two decimal places. Divide it by 24 if you want an approximate number of days of continuous recording.
Check your camera or recorder settings for the bitrate values when possible. If a device uses variable bitrate, choose an average that reflects the conditions you expect. A higher assumed average gives a shorter recording-time estimate, while a lower average gives a longer one.
How the Video Recording Time Calculator formula works
The calculator divides usable storage by the combined video and audio bitrate, with an adjustment for recording overhead. Its formula is:
Recording time in hours = Storage capacity in GB × 8,000 × Storage available for recordings ÷ 100 ÷ [(Combined video bitrate + Combined audio bitrate) × (1 + Recording overhead ÷ 100) × 3,600]
Multiplying decimal gigabytes by 8,000 converts storage capacity to megabits. The available-storage percentage reduces that amount to the space allocated to recordings. The video and audio rates are added together, and the overhead percentage increases the estimated rate at which storage is consumed. Finally, dividing by 3,600 converts seconds to hours.
Worked example: 128 GB at 8 Mbps
Assume a security camera system has 128 GB of storage, all of it is available for recordings, and its average combined video bitrate is 8 Mbps. For this example, assume there is no recorded audio and no additional recording overhead.
- Storage capacity: 128 GB
- Storage available for recordings: 100%
- Combined video bitrate: 8 Mbps
- Combined audio bitrate: 0 Mbps
- Recording overhead: 0%
The available storage is 128 × 8,000, or 1,024,000 megabits. At 8 megabits per second, that provides approximately 128,000 seconds of recording. Dividing by 3,600 gives 35.56 hours, or about 1.48 days of continuous recording.
These values are assumptions for the example. If audio is enabled, part of the drive is unavailable, or recording overhead is added, the estimated time will be shorter.
Use cases for the Video Recording Time Calculator
Planning storage for a home security camera
Before choosing a memory card or recorder, estimate how long it could hold continuous footage at your camera’s average bitrate. Compare the result with the amount of history you want to review. If the estimate is too short, you can consider a larger storage capacity or review the camera’s recording settings.
Estimating recording time for multiple cameras
A recorder serving several cameras consumes storage for all streams that are recorded. If four cameras each average an assumed 4 Mbps for video, enter a combined video bitrate of 16 Mbps. Add any recorded audio streams separately in the combined audio field.
Camera bitrates do not have to be identical. Add the average rate for each camera that records to the storage you are evaluating. The result estimates how long the shared space can hold their simultaneous continuous recordings under those assumptions.
Comparing recording settings
Run the calculation with different assumed average bitrates to see how storage demand changes. Resolution, frame rate, image quality, and compression settings can affect bitrate, but their effects vary by camera and scene. Use a measured or manufacturer-provided average bitrate where available instead of assuming that a particular resolution always uses the same rate.
Allowing space for other files
A storage device may also hold system data, snapshots, or other files. The available-storage field lets you account for space that cannot be used for recordings. For instance, if you expect 80% of a 64 GB device to be available, the calculation uses 51.2 GB for footage.
Other factors to consider when calculating Recording Time
- Variable bitrate: Many cameras adjust their bitrate as the scene changes. Motion, lighting, and image detail can make actual storage use rise or fall over time.
- Continuous versus motion-triggered recording: The result assumes continuous recording. A system that records only during events may cover a longer calendar period, depending on how often events occur and how long each clip lasts.
- Retention and overwrite settings: A recorder may delete or overwrite older footage when storage fills, or apply a retention rule that removes footage sooner. Check those settings when planning how far back you can review.
- Usable capacity and other files: Formatting, system use, and existing files can leave less space for recordings than the advertised capacity. The calculator uses decimal GB, so make sure your capacity and available-space figures are consistent with that convention.
- Recording overhead: File containers and other recording-related data can add storage use. The overhead setting is an estimate, and its effect depends on how your system stores footage.
- Audio: Recorded audio adds to the total bitrate. If multiple cameras record audio, include the combined average audio rate.
For a more useful planning estimate, check the recorder’s actual storage consumption over a representative period and compare it with the calculator result. Busy scenes and nighttime conditions can produce different averages from quiet daytime footage.
Frequently asked questions
How long will 128 GB record security camera footage?
It depends on the bitrate and the storage available. At an assumed 8 Mbps video bitrate, with 100% of 128 GB available and no audio or overhead, the estimate is 35.56 hours of continuous recording. Different settings will produce a different result.
How do I calculate recording time for multiple cameras?
Add the average video bitrates of the cameras that record to the same storage and enter the total as Combined video bitrate. Add their audio bitrates separately if audio is recorded. The resulting estimate assumes those streams record continuously at their entered averages.
Does a higher bitrate reduce recording time?
Yes. When usable storage stays the same, a higher combined bitrate fills it faster. If the total bitrate doubles and the other inputs remain unchanged, the estimated continuous recording time is cut in half.
Does the calculator account for motion-only recording?
No. It estimates continuous recording time. Motion-only recording can spread the available recording hours over a longer calendar period, but the result depends on the frequency and length of recorded events.
Why is my recorder’s actual storage time different from the estimate?
Actual bitrates can vary with motion and scene detail, and the device may reserve space or store other files. Audio, recording overhead, retention rules, and overwrite settings can also affect how much footage remains available. Adjust the inputs using your system’s observed averages and available space for a closer estimate.