How do I find the bitrate for a target file size?

Multiply the target size in bytes by 8 to get bits, then divide by the duration in seconds and by 1000 to get the total kbps. Subtract the audio bitrate to get the video bitrate. This tool does all of that.

Why subtract the audio bitrate?

The container holds both streams, so the total bitrate is video plus audio. To keep the file at your target size you give the video only what is left after the audio bitrate.

Is anything uploaded?

No. The calculation runs entirely in your browser and no files or data are sent anywhere.

Bitrate Calculator (Audio + Video)

Find the bitrate needed to fit a target file size.

Bitrate calculator for audio and video

Plan an encode by working backwards from a target file size. Enter the size you want, the clip duration and the audio bitrate, and this tool gives you the total bitrate plus the video bitrate to set — handy for two-pass encoding to a disc, upload limit or streaming budget.

The formula is target bytes × 8 ÷ seconds ÷ 1000 = total kbps, then subtract the audio bitrate for the video bitrate. Everything runs locally in your browser.