H.264 inside an MP4 container is the most universally compatible video format — it plays on every smartphone, smart TV, browser, video editor and social media platform. When in doubt, MP4 is the safest format to share.

What do the quality presets do?

They tune the H.264 CRF (constant rate factor). High = CRF 20 (visually near-lossless, largest file). Balanced = CRF 23 (default, recommended for most uses). Small = CRF 28 (visible compression but tiny — fine for messaging).

Will MP4 work in older players too?

Yes. H.264 baseline support goes back decades and works on virtually every modern device, plus a huge range of legacy hardware including older smart TVs, game consoles, and basic media boxes.

Is this slower than WebM?

No — this is significantly faster. The ultrafast x264 preset trades a little compression efficiency for very high encoding speed. For maximum compression, use the WebM converter instead.

Does it re-encode audio too?

Yes, audio is re-encoded to AAC at 128 kbps for guaranteed MP4 compatibility. AAC at 128 kbps sounds great for speech and good for music — comparable to MP3 at 192 kbps.

Is my video uploaded?

No. ffmpeg.wasm processes everything inside your browser via WebAssembly. The file never leaves your device.

Convert Video to MP4

Convert MOV, WebM, AVI, MKV, FLV and more to MP4 (H.264 + AAC) — entirely in your browser, no upload.

100% client-side · no upload

Video file (MOV, WebM, AVI, MKV…)

Load a video file to begin.

How to convert a video to MP4

Load your video file — MOV, WebM, AVI, MKV, FLV and more are accepted.
Pick a quality preset: High for archives, Balanced for everyday use, Small for chat/email.
Click Convert to MP4 and wait for H.264 + AAC encoding.
Download the resulting .mp4 file.

Common use cases

iPhone MOV to MP4: Convert iPhone-recorded .mov files into universally playable .mp4 for sharing.
WebM to MP4: Re-encode a downloaded WebM into MP4 for compatibility with iMovie, Premiere or QuickTime.
Old AVI rescue: Migrate ancient AVI/MKV files from a hard drive to a modern, portable format.
Social platform uploads: Many sites prefer MP4 — converting first avoids server-side recompression artefacts.

Related tools: Convert to WebM · Video Compressor · Video Trimmer · Video Resizer

Frequently Asked Questions

Why MP4 (H.264)?: H.264 inside an MP4 container is the most universally compatible video format — it plays on every smartphone, smart TV, browser, video editor and social media platform. When in doubt, MP4 is the safest format to share.
What do the quality presets do?: They tune the H.264 CRF (constant rate factor). High = CRF 20 (visually near-lossless, largest file). Balanced = CRF 23 (default, recommended for most uses). Small = CRF 28 (visible compression but tiny — fine for messaging).
Will MP4 work in older players too?: Yes. H.264 baseline support goes back decades and works on virtually every modern device, plus a huge range of legacy hardware including older smart TVs, game consoles, and basic media boxes.
Is this slower than WebM?: No — this is significantly faster. The ultrafast x264 preset trades a little compression efficiency for very high encoding speed. For maximum compression, use the <a href="/video/to-webm/">WebM converter</a> instead.
Does it re-encode audio too?: Yes, audio is re-encoded to AAC at 128 kbps for guaranteed MP4 compatibility. AAC at 128 kbps sounds great for speech and good for music — comparable to MP3 at 192 kbps.
Is my video uploaded?: No. ffmpeg.wasm processes everything inside your browser via WebAssembly. The file never leaves your device.

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