How to Budget Video Bitrate for a File-Size Limit

Budget audio and video together when a clip must fit a file-size limit.

Use the Streaming Bitrate Calculator alongside this illustrative example.

A practical example

Enter 1 minute, 10 in the size field and 128 kbps audio. The calculator labels size MB but treats each unit as 1,048,576 bytes (MiB). It estimates about 1,398 kbps total, subtracts audio, then reserves 3% headroom: about 1,232 kbps video. If a service uses decimal MB, enter about 9.54 for a 10,000,000-byte cap and still inspect the output.

Check the result

If text becomes unreadable at that budget, compare a shorter clip or a smaller frame size. Halving the duration gives the remaining footage approximately twice the bitrate allowance at the same target size.

Try a comparison

Keep size at 10 and audio at 128 kbps; change duration from 1 minute to 0.5 minutes. The recommended video bitrate rises from about 1,232 to 2,588 kbps. Fixed audio and the 3% margin explain why the video result is not exactly doubled.

What this does not establish

This is a planning calculation, not a guarantee of encoder output size. Inspect the finished file in bytes before uploading.

Report unclear guidance or a result that needs checking.