mimicThe formula
File size (bytes) = bitrate (bits per second) × seconds ÷ 8. Add video and audio bitrates together first. 8 Mbps video + 128 kbps audio for 60 seconds = 8.128 × 60 ÷ 8 = 60.96 MB.
Going the other way, the bitrate that fits a limit = size × 8 ÷ seconds, minus your audio bitrate.
YouTube's recommended upload bitrates
For SDR video, from YouTube's encoding settings page. HDR recommendations are higher: 10 Mbps for 1080p at standard frame rates.
| Resolution | 24, 25, 30 fps | 48, 50, 60 fps |
|---|---|---|
| 2160p (4K) | 35–45 Mbps | 53–68 Mbps |
| 1440p (2K) | 16 Mbps | 24 Mbps |
| 1080p | 8 Mbps | 12 Mbps |
| 720p | 5 Mbps | 7.5 Mbps |
| 480p | 2.5 Mbps | 4 Mbps |
| 360p | 1 Mbps | 1.5 Mbps |
Audio: 128 kbps mono, 384 kbps stereo, 512 kbps 5.1. YouTube asks for H.264, MP4, AAC-LC or Opus at 48 kHz.
Upload size limits
| Where | Max file |
|---|---|
| TikTok In-Feed ad | 500 MB |
| TikTok via other apps | 4 GB |
| Instagram Reels ad | 4 GB |
| LinkedIn post | 5 GB |
| TikTok Studio | Under 10 GB |
| YouTube | 256 GB or 12 hours |
Worked example
A 45-second 1080p 30 fps ad for TikTok, which caps ad files at 500 MB.
At YouTube's 8 Mbps + 128 kbps audio: 8.128 × 45 ÷ 8 = 45.7 MB. Well under.
The most it could use: 500 × 8 ÷ 45 = 88.9 Mbps total. You'll never need that for 1080p.
Sources
- YouTube Help, Recommended upload encoding settings
- TikTok Ads Help, Auction In-Feed ad specifications (In-Feed Standard safe zone file, 720×1280)
- TikTok for Developers, Content Posting API: media transfer guide (video restrictions)
- Meta Ads Guide, Instagram Reels video ads (safe zone, size, length)
- LinkedIn Help, Video sharing troubleshooting (video specs)
- TikTok Support, Creator tools on TikTok (TikTok Studio upload requirements)
- YouTube Help, Upload videos longer than 15 minutes (256 GB or 12 hours)
Questions
How big is a 1-minute 1080p video?
At YouTube's recommended 8 Mbps plus 128 kbps audio, about 61 MB. Phones often record at higher bitrates, so the camera file is usually bigger.
How do I calculate video bitrate from file size?
Bitrate = file size in bits ÷ length in seconds. A 300 MB, 2-minute file: 300 × 8 ÷ 120 = 20 Mbps.
Why is my exported file a different size?
Encoders use variable bitrate: simple scenes get fewer bits and busy ones more. Containers add a small overhead too. The result is an estimate.
Is a higher bitrate always better?
Up to a point. Platforms re-encode everything you upload, so going far above their recommended bitrate mostly makes a bigger file to upload.
Is MB 1,000 or 1,024 kB here?
1,000. Upload limits are usually written in decimal units, so the calculator uses 1 MB = 1,000,000 bytes.