Video bitrate calculator for a target file size

Work backwards from a size limit. Reserve room for audio before choosing your video bitrate.

The formula

Video Mbps = target MB × 8 ÷ seconds ÷ (1 + overhead ÷ 100) − audio kbps ÷ 1,000

Example: fit five minutes into 100 MB

With 128 kbps audio and a 2% allowance, the video budget is about 2.486 Mbps. Without an overhead allowance it is about 2.539 Mbps.

A budget is not an encoder guarantee. Choose a supported codec, test visual quality and leave additional margin for strict upload limits. If audio alone fills the target, the calculator asks you to revise the inputs.