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How much storage do my recording settings need?
Check storage before a recording session, not after the card fills
A 90-minute recording at 20 Mbps video plus 320 kbps audio uses an estimated 13.716 GB before container overhead. Adding a chosen 20% planning allowance gives about 16.46 GB per copy. Use your recording bitrate, not a lower export or streaming preset.
The numbers below assume the inputs in the assumptions section. Change any of them in the calculator to fit your own project.
You are preparing to record a 90-minute talk and need to know whether there is enough free space on the recording device. The useful inputs are the planned recording duration and the bitrates actually written to disk. A label such as 1080p or 4K does not specify storage on its own.
For this example, assume the recorder is set to 20 Mbps of video and one audio stream totaling 320 kbps. Enter those as custom values rather than selecting a resolution preset. The result is the estimated size of the recorded file at those rates, not the size of a later upload, delivery export, or editing project.
Before the session, record a short representative clip with the real codec, frame rate, and quality mode. Check its average bitrate and confirm that the device can sustain the recording. Then budget separate space for extra takes, backup copies, and editing media. The worked example adds a chosen 20% allowance, but a variable-bitrate recording or a long overrun can exceed that allowance.
Prefer the full version with the explanation and examples? Open the calculator page directly.
Check my recording storage5,400 seconds for one continuous recording; multiple cameras need their own totals.
Use a configured constant bitrate or a realistic average for variable bitrate, not a resolution-only estimate.
The total across recorded audio streams. Do not add it again if your measured bitrate already includes audio.
1 GB = 1,000,000,000 bytes. Binary GiB and MiB describe the same bytes with different divisors.
A chosen example margin, not a calculator default or a guarantee. Container overhead and variable-bitrate peaks are excluded from the base result.
Reserve storage for a 90-minute single-camera recording and one backup
- 1Combine video and audio in the same units: 20 + 320 ÷ 1,000 = 20.32 Mbps.
- 2Multiply by duration: 20.32 × 5,400 = 109,728 megabits for the recording.
- 3Convert bits to bytes: 109,728 ÷ 8 = 13,716 MB. Divide by 1,000 to get 13.716 GB, displayed as 13.72 GB.
- 4For a binary comparison, divide 13,716,000,000 bytes by 1,073,741,824: about 12.774 GiB. The file has not become smaller; only the unit changed.
- 5Apply the chosen allowance outside the calculator: 13.716 × 1.20 = 16.4592 GB, or about 16.46 GB per copy. Two such budgets total 32.9184 GB, about 32.92 GB across the recording and backup locations.
Compare the per-copy budget with actual free bytes on each destination, not the capacity printed on a card. A nominal 16 GB card cannot meet this 16.46 GB budget. Keep the backup on a separate device; editing caches and proxies need additional space.
- Using an export bitrate for the camera recording. A small delivery file does not tell you how much original footage the recorder will create.
- Assuming 4K always needs a particular number of GB per hour. Codec, frame rate, scene detail, and the encoder's rate-control settings determine the bitrate.
- Reading Mbps as MB/s. There are eight bits per byte, so skipping the division by eight overestimates storage eightfold.
- Comparing a GB estimate directly with a GiB free-space figure. Convert both to the same unit before deciding whether the recording fits.
- Treating the 20% allowance as unlimited protection. Include real overruns, extra takes, container overhead, separate audio, and any additional cameras.
- Confusing capacity with write speed. Having enough free space does not prove the card or disk can sustain the recorder's peak data rate.
Will a 16 GB card hold this 90-minute recording?
The base estimate is 13.716 GB, but the example's chosen 20% allowance raises the per-copy budget to 16.4592 GB. A nominal 16 GB card cannot meet that budget. Check usable free space and choose adequate capacity and a suitable sustained write-speed rating.
Is this the recording size or the exported video size?
It is the size for whichever bitrate and duration you enter. This example uses recording settings. A later export must be estimated again with its own video bitrate, audio bitrate, and final duration. Proxies, render caches, and project backups are not included.
Does choosing H.265 instead of H.264 automatically halve the file?
No. At the same video bitrate and duration, the estimated video bytes are the same. A codec may achieve acceptable quality at a different bitrate, but the appropriate rate depends on content, settings, and quality requirements. Test rather than assume a fixed reduction.
How do I estimate variable-bitrate recordings?
Use an average bitrate from representative recordings for the base estimate and allow for higher rates or longer takes. If your recorder specifies a maximum bitrate, you can run a separate estimate with that rate as a planning bound. Container overhead is still separate.
What changes if I record two cameras or separate audio?
Estimate each camera and audio recording separately, then add the file sizes for shared storage and backup planning. Two identical camera recordings double the video-and-audio budget. Do not count an audio stream twice if it is already included in the measured combined bitrate.