ReelVideo file size calculator: bitrate × length
File size = (video bitrate + audio bitrate) × length ÷ 8. A 10-minute 1080p video at YouTube's suggested 8 Mbps with 384 kbps audio comes to about 629 MB. Enter your own numbers, or work back from a size limit to the bitrate that fits.
YouTube's suggested upload bitrates
From YouTube's upload encoding settings (SDR, H.264 in MP4, checked 30 October 2026). Stereo audio: 384 kbps.
| Resolution | 24-30 fps | 48-60 fps |
|---|---|---|
| 2160p (4K) | 35-45 Mbps | 53-68 Mbps |
| 1440p | 16 Mbps | 24 Mbps |
| 1080p | 8 Mbps | 12 Mbps |
| 720p | 5 Mbps | 7.5 Mbps |
| 480p | 2.5 Mbps | 4 Mbps |
Why the real file differs
The result is an estimate. Encoders change the bitrate from scene to scene, so a flat animated film often comes out far smaller than the number above, while busy scenes with grain or particles come out bigger. The container adds a little on top. MB here means 1,000,000 bytes; Windows shows MiB (1,048,576 bytes), which is why the same file looks about 5% smaller there.
Animated films are small
Films animated in code, with flat colour and clean shapes, compress very well. Every sample loop on this site is an 8-second 720p clip under 1.5 MB. If you want films like that from your own coding agent, see the 121 styles.
Make the video itself
ReelStyles is a set of 121 finished film styles for AI coding agents like Claude Code, Codex and Cursor, and 41 of them are made for 9:16. Your agent animates the whole film in code on your computer. 6 of the styles are free.
See the 121 styles Get 6 styles free
More free tools: all tools.