Video Format Converter

Convert between MP4 / WebM / MOV / MKV / AVI / GIF. Solves "this file won't play here" problems.

Fully local processing — your file never leaves the browser

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Drag & drop a video, or click to select

Supported: MP4, MOV, AVI, MKV, WebM, FLV, etc. / Max 500 MB

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Download converted file

Popular uses

Convert MOV/MKV to MP4Improve upload compatibilityFix playback format issues

Next tools

Codec Compatibility Matrix Video Compressor Audio Extractor

What this tool does

Six container targets
Quality preset selector
Local processing

How to use

1
Pick a video
Any common format.
2
Pick output format
MP4 / WebM / MOV / MKV / AVI / GIF.
3
Pick quality
High / Standard / Light.
4
Convert
Download link appears.

What each setting means

Output format

MP4 has the best compatibility. WebM is browser-friendly.

Quality

Maps to a CRF preset internally; standard ≈ CRF 23.

Recommended settings

iPhone .mov for sharing

MP4 standard

Plays on every iOS / Android device.

Web embed

WebM standard

Smaller and supports transparency.

Embedded in a slide deck

MP4 high

PowerPoint / Keynote friendly.

Common pitfalls

Symptom: WebM won't play somewhere

Cause: Some players / SNS don't support WebM.

Fix: Use MP4 (H.264) for max compatibility.

Symptom: Quality dropped

Cause: Light preset, or already-compressed source.

Fix: Pick High preset.

Equivalent FFmpeg commands

Reference commands you can run on the desktop FFmpeg CLI.

MOV → MP4

ffmpeg -i input.mov -c:v libx264 -crf 23 -preset fast -c:a aac -b:a 128k -movflags +faststart output.mp4

MP4 → WebM (VP9)

ffmpeg -i input.mp4 -c:v libvpx-vp9 -crf 32 -b:v 0 -c:a libopus output.webm

Browser support & limits

MP4 / WebM / MOV / MKV / AVI / GIF outputs
Up to 500MB input

Privacy

This tool runs ffmpeg.wasm directly in your browser. Files never leave your device — everything runs locally. Read the privacy policy →

Frequently asked questions

Audio-only output?

No — this tool is video-to-video. Use the Audio Extractor for audio.

No re-encode just to change container?

This tool re-encodes for simplicity. Use FFmpeg stream-copy on the desktop if needed.

MKV vs MP4?

Use MP4 for sharing / phones / SNS. MKV is best when you need multiple subtitle / audio tracks.