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Video file size calculator

Estimate media payload size from duration, average video bitrate and audio bitrate. Results include decimal megabytes and binary mebibytes so the units remain clear.

By Demovela · Published · 2 min read + calculator

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Runs in your browser. No signup, upload or saved inputs.

Enable JavaScript to calculate here, or use the formula and worked example below.

When this is useful

This is useful for an initial upload or delivery budget. It assumes the entered average bitrates apply over the whole duration and does not inspect a file or predict an encoder’s exact output.

How to use this calculator

  1. Enter the duration in seconds and video bitrate in megabits per second. Add audio bitrate in kilobits per second, or zero when there is no audio.
  2. Read the estimated payload in MB and MiB. Compare it with the destination’s actual size limit using consistent units.
  3. Leave room for container overhead and bitrate variation, then measure the final export. Keep a readable source if another encode is needed.
CHECK THE MATH

Worked calculation

An illustrative 60-second video at 4 Mbps with 128 kbps audio has a combined bitrate of 4.128 Mbps. Its estimated media payload is 30.96 MB, approximately 29.53 MiB, before container overhead.

Formula and units

MB = (video Mbps + audio kbps ÷ 1000) × seconds ÷ 8. MiB = MB × 1,000,000 ÷ 1,048,576.

Limits and checks

Actual files can differ because of variable bitrate, metadata and container overhead. A result below an upload limit is a planning estimate, not a guarantee that the finished file will be accepted.

Your next step

If you have a fixed size ceiling, use the bitrate calculator to estimate the remaining video budget after audio.

References and scope

Examples are illustrative production guidance, not measured customer results. General workflows are not promises of product compatibility. Read our editorial approach and current Demovela scope.

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