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FormatDrop
How-To Guide

How to Compress an MP4 Video

MP4 video files can grow large — 4K footage easily exceeds 1 GB per minute. Compressing MP4 reduces file size for email, social media uploads, or storage. The right compression preserves quality while shrinking the file 50–80%. Three main techniques: lower CRF (more compression), reduce bitrate, or downscale resolution.

Open the MP4 to WebM Converter

Step-by-step instructions

  1. 1

    Know what works today

    A dedicated MP4 compressor is coming soon to FormatDrop — it is not live yet. Today the closest browser route is the MP4 to WebM converter linked above. It re-encodes your MP4 to VP9 WebM locally in your browser — nothing is uploaded, and the output is typically 30–40% smaller at the same visual quality. Free plan: up to 5 files, 10 MB each. Pro: files up to 500 MB. If the file must stay MP4, use HandBrake (free, Windows/Mac/Linux) or FFmpeg on your computer today.

    Go to converter
  2. 2

    Choose a compression level in your encoder

    In HandBrake or FFmpeg, pick a target. Light: CRF 22, same resolution — around 30% smaller. Medium: CRF 26 with a 720p downscale — around 60% smaller. Strong: CRF 30 with a 480p downscale — around 80% smaller. A higher CRF number means more compression and lower quality. The same presets are planned for the upcoming FormatDrop compressor.

  3. 3

    Play it back and verify

    Play the output through and compare the file size. Most viewers cannot tell CRF 23 from the source on a phone. CRF 28 is fine for casual viewing. Above CRF 28, the quality loss starts to show.

Why compress an MP4?

Compressing MP4 is the daily task of sharing video — getting from camera-original size to upload-acceptable size while preserving viewing quality.

Your files never leave your device

FormatDrop runs the conversion engine entirely inside your browser using WebAssembly. No file upload. No server. Nothing stored. You can verify this by opening DevTools → Network tab and watching: zero upload requests.

Frequently asked questions

FFmpeg command to compress MP4?
`ffmpeg -i input.mp4 -c:v libx264 -crf 24 -preset slow -c:a aac -b:a 128k output.mp4`. CRF 18 = visually lossless, CRF 23 = default, CRF 28 = fairly compressed but watchable. Lower CRF = better quality, larger file.
What's the difference between CRF and bitrate compression?
CRF (Constant Rate Factor) is quality-based — encoder uses bits where needed to maintain perceptual quality, varying bitrate per scene. Bitrate is fixed — predictable file size but inconsistent quality. CRF is better for typical use; bitrate is better when targeting a specific file size.
How do I downscale resolution?
Add `-vf scale=-2:720` (720p, height) or `-vf scale=1280:-2` (1280px width, height auto). Combined with CRF: `ffmpeg -i input.mp4 -vf scale=-2:720 -c:v libx264 -crf 23 -c:a aac output.mp4`.
Convert MP4 to WebM — Free

No account. No upload. Works in any browser.

Related guides

How to Convert MOV to MP4How to Convert MP4 to GIFHow to Convert MKV to MP4How to Convert MOV to MP4 on iPhone