How is video file size calculated from bitrate?

File size in bits equals total bitrate (video plus audio) multiplied by duration in seconds; divide by 8 for bytes. For example, 8 Mbps video plus 192 kbps audio for 10 minutes is about (8,000,000 + 192,000) x 600 / 8 = 614 MB.

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

Multiply the target size by 8 to get total bits, divide by the duration in seconds for total bitrate, then subtract the audio bitrate to get the video bitrate. The tool does this for you when you choose to solve for bitrate.

Are decimal or binary units used?

Decimal — 1 MB = 1,000,000 bytes and 1 GB = 1000 MB, which matches how bitrate and storage are usually quoted for video. Nothing you enter is sent anywhere; it all runs in your browser.

Video Bitrate Calculator

The relationship between bitrate, duration and file size is one clean identity:

file size (bits) = total bitrate (bits/s) × duration (s)

where total bitrate is the video bitrate + audio bitrate. Divide by 8 to get bytes. So an 8 Mbps video with 192 kbps audio running 10 minutes lands at roughly 614 MB.

Switch the mode to solve the other way: enter a target file size and the duration, and the calculator returns the video bitrate you need (after reserving room for the audio track). Decimal units throughout (1 GB = 1000 MB), and everything is computed locally in your browser — nothing is uploaded.