CalcBrew

Video Converters

Compress Video

A phone video at 4K is 350 MB per minute; a 1080p H.264 encode is a tenth of that and looks the same on a phone. Set a target size — “under 25 MB for email” — and let the tool pick the settings.

Runs in your browser when it can; large or unusual files use our EU server and are deleted within 1 hour.

Drop MP4, MOV, MKV, WebM files here

or click to browse · paste from clipboard · up to 4000 MB each

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Why convert MP4 to MP4

Video size is driven by bitrate. Phones record at very high bitrates for editing headroom; re-encoding at a bitrate matched to the resolution and content halves or quarters the file with no visible change at normal playback size.

The encoder is the browser’s hardware-accelerated H.264 encoder, so a 5-minute 1080p clip takes about a minute on a laptop, and nothing is uploaded. Two-pass style bitrate targeting hits the size you ask for within a few percent.

How it works

  1. Drop your files onto the box above, click it to browse, or paste from the clipboard.
  2. Adjust the options if you need to — the defaults suit most cases.
  3. Press Convert. Small files are handled on your device; larger ones are sent to our server with a progress bar.
  4. Download the MP4 — individually or all at once.

About the formats

MP4 · MPEG-4 Part 14 video · .mp4

The video format that works everywhere: phones, TVs, browsers, social networks. Normally H.264 video with AAC audio.

  • MP4 is a container; the codec inside (H.264, HEVC/H.265, AV1) decides what can play it.
  • H.264 MP4 is the safe choice for uploads and sharing; HEVC MP4 from newer iPhones needs extra codecs on Windows.
  • The “moov atom” placement decides whether a browser can start playing before the whole file downloads.

MOV · QuickTime movie · .mov

Apple’s QuickTime container, the default for iPhone videos and Mac screen recordings; very close to MP4 but not accepted everywhere.

  • MOV and MP4 share the same underlying structure, so MOV to MP4 usually only needs repackaging, not re-encoding.
  • iPhone MOV files are often HEVC (H.265) with HDR, which Windows and many web apps cannot play without conversion.
  • Screen recordings on Mac are MOV with H.264 and can be very large.

MKV · Matroska video · .mkv

An open container that can hold any codec plus multiple audio tracks, subtitles and chapters; popular for rips and downloads, unsupported by iPhone and many TVs.

  • MKV to MP4 keeps the video quality when the codec is H.264 or HEVC — only the container changes.
  • MP4 cannot carry every MKV feature: soft subtitles and some audio codecs (e.g. DTS) must be converted or dropped.
  • Most desktop players (VLC, MPV) play MKV; Safari, iOS and PowerPoint do not.

WebM · WebM video · .webm

The royalty-free web video format (VP8/VP9/AV1 video, Vorbis/Opus audio) produced by browser screen recorders, Discord and many online tools.

  • WebM is based on Matroska and plays in every browser, but not in iMovie, Premiere or on most phones without conversion.
  • Browser recording APIs output WebM, which is why screen recordings from web apps come as .webm.
  • WebM to MP4 requires re-encoding the video, because MP4 does not carry VP9 widely.

Related conversions

MOV to MP4PopulariPhone/Mac MOV to MP4, usually without re-encoding.MP4 to WebMOn-deviceMP4 to smaller WebM (VP9/Opus) for websites.Compress ImagePopularOn-deviceReduce image file size, optionally to a target in KB.MKV to MP4PopularMKV to MP4 by remuxing, lossless and fast.WebM to MP4PopularBrowser screen recordings (WebM) to MP4.MP4 to GIFPopularOn-deviceVideo clip to an animated GIF with trim and size controls.

More in Video Converters · All converters

Frequently asked questions