How do I calculate video bitrate for a target size?
Multiply target megabytes by 8,000, divide by duration in seconds, then subtract the audio bitrate. Use a safety margin below the platform limit.
Interactive file-size tool
Video bitrate and target file size calculator.
Calculate the video bitrate available for a 20MB, 50MB, or custom target. You can also estimate final file size from video bitrate, audio bitrate, and duration.
Video details
Share a reproducible plan
Save these settings for a teammate or a forum answer. MB means 1,000,000 bytes; kbps means 1,000 bits per second. No video is included.
Target-size result
1,171 kbps video bitrate
- Working target
- 9.5 MB
- Total bitrate
- 1,267 kbps
- Duration
- 60 sec
Low bitrate. Often more practical around 480p–720p.
File-size estimate
Approximately 11.97 MBBased on 1,500 kbps video plus 96 kbps audio for 60 seconds.
These are planning estimates, not guarantees. Variable bitrate, container overhead, metadata, codec behavior, and browser implementation can change the final file size. Inspect the exported file before uploading.
Target bitrate formula
Total kbps = target MB × 8,000 ÷ duration in seconds.
Video kbps = total kbps − audio kbps.
Estimated size formula
File MB = (video kbps + audio kbps) × duration ÷ 8,000.
Use a safety margin because real encoders are not perfectly exact.
Calculator FAQ
How do I estimate video file size?
Add video and audio bitrate, multiply by duration in seconds, then divide by 8,000 to estimate megabytes.
Why does the exported size differ from the calculator?
Variable bitrate, container overhead, metadata, multiple streams, and encoder behavior can move the final size above or below the estimate.
What safety margin should I use?
Five percent is a practical starting point. Increase it if the destination rejects files at or very close to its stated limit.