Why should I use 2-pass encoding with FFmpeg?

Two-pass variable bitrate (VBR) encoding analyzes the entire video during the first pass to identify complex action scenes versus static scenes, ensuring the second pass hits the exact target file size without overshooting.

What is the minimum video bitrate for acceptable quality?

For 1080p video, bitrates above 1,500 kbps provide good quality. Below 500 kbps, macroblocking compression artifacts become noticeable, so lowering resolution to 720p or 480p is recommended.

Media & Images

Target Video Bitrate & File Size Matcher

The problem: Exporting videos that exceed Discord's 25MB free limit or email 20MB attachments forces users into trial-and-error re-encoding.

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100% In-Browser Execution. Zero server uploads. Your data never leaves this tab — disconnect your internet and the tool keeps working.

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100% In-Browser Execution. Zero server uploads. Your data never leaves this tab — disconnect your internet and the tool keeps working.

Target Video Bitrate

1,169 kbps

1.17 Mbps video rate

Target File Cap

25 MB

With 5% container margin

Total Runtime

2m 30s

150 total seconds

Audio Budget

128 kbps

Stereo AAC sound

File Size Limits & Duration

Maximum File Size (MB)

Platform Limits:

Minutes

Seconds

FFmpeg 2-Pass Encoding Command

ffmpeg -i input.mp4 -c:v libx264 -b:v 1169k -pass 1 -an -f null /dev/null && ffmpeg -i input.mp4 -c:v libx264 -b:v 1169k -pass 2 -c:a aac -b:a 128k output.mp4

Run this command in terminal to encode input.mp4 using 2-pass VBR targeting exactly 25 MB.

Target Video Bitrate & File Size Matcher: the complete guide

A Video Bitrate and File Size Matcher calculates target video and audio export bitrates (in kbps and Mbps) to fit videos under strict platform file size caps (such as Discord's 25 MB free limit, Slack's 10 MB cap, or WhatsApp's 64 MB limit). Guessing export bitrates in Premiere, Final Cut, or Handbrake often leads to files that are either a few megabytes too large to upload or unnecessarily low quality. This tool computes exact 2-pass VBR bitrates with an automated FFmpeg terminal command.

The Mathematics of Video Bitrate and File Size

Digital video file size is determined solely by bitrate and duration: File Size (Bits) = Total Bitrate (bps) × Duration (seconds). One megabyte equals 8,192 kilobits. Dividing the target size by duration yields the total usable bitrate budget. Subtracting the audio bitrate (typically 128 kbps stereo AAC) and a 5% safety margin for MP4 container metadata determines the target video bitrate.

Step by step: how to use Video Bitrate Matcher

1
Enter your maximum target file size in MB or click a platform preset (Discord, Slack, WhatsApp).
2
Input your video duration in minutes and seconds.
3
Inspect the calculated target video bitrate in kbps and Mbps.
4
Review the warning alert if your video is too long for the selected file size budget.
5
Copy the generated FFmpeg 2-pass command to encode your video directly in terminal.

Security & privacy

Client-only calculation. No video files or media assets are uploaded; all calculations execute instantly in local browser memory.