Compress MP4
Smaller MP4, still MP4, made on your own device.
MP4 in, MP4 out. The default here is Balanced quality — the setting that usually halves a phone or camera MP4 with no visible change. Use the size box if you have a specific limit instead.
Open the compressor → Opens the compressor with the quality preset applied.- 100% freeNo account, no daily quota, no paid tier.
- Nothing is uploadedFiles are processed on your device and never reach a server.
- No catch on the outputNo watermark, no forced downscaling, no size cap.
- Updated in the openEvery fix and every new tool is written down on the changelog page.
What an MP4 is, and why it is often bigger than it needs to be
MP4 is a container, not a codec: a box that holds a video stream (almost always H.264, sometimes H.265/HEVC or AV1), an audio stream (usually AAC) and an index. Its size is set by the bitrate the recording device chose, and devices choose high bitrates on purpose — a phone encodes in real time with a hardware encoder tuned for speed and battery, not for efficiency, so it spends two or three times the bits a careful second pass would need for the same picture. That gap is what compression recovers. A 1080p phone clip at 17 Mbps typically looks identical at 5–6 Mbps, which is a file one-third the size.
The Balanced preset targets that point: a bitrate chosen per pixel and frame so that the same setting gives the same look at any resolution. The High preset stays closer to the source for archiving; Small aims at phone-screen viewing. All three keep the container as MP4, the video as H.264 and the audio copied as-is, so the result plays on exactly the same devices as the original.
How to compress an MP4 here
Drop the file or click Choose file. The page reads its resolution, frame rate, length and current bitrate in a moment — the file is not uploaded and not decoded yet. Leave Balanced selected, or switch to a percentage preset or a size in MB on the Basic tab. The estimate line shows the expected output size and resolution. Press Compress: the video is decoded, re-encoded by your device's hardware H.264 encoder and written straight back to disk, so the size of the input does not matter and a multi-gigabyte file uses no more memory than a small one. Play the result in the page, then download it.
If the source is 4K and the video will be watched on a phone or laptop, set Resolution to 1080p in Advanced: 4K carries no visible benefit on those screens and the file drops by another two-thirds. If the MP4 came from a screen recorder at 60 fps, cap the frame rate at 30. If the MP4 is already efficient — a download from a streaming site, a YouTube export — the estimate will tell you that compressing it further will not help; MP4s like that are already at the bitrate this tool would choose.
Keeping compatibility
H.264 in MP4 is the one combination that plays on everything made in the last fifteen years, which is why it is the default. H.265/HEVC in MP4 gives files about a third smaller at the same quality and plays on every iPhone, Mac, Android phone and modern Windows PC, but not in some browsers or older TVs; pick it in Advanced when you know where the file is going. The output carries the rotation flag and creation date from the source, so portrait phone videos stay portrait and photo apps still sort them by date. The compressed MP4 can go straight to Trim Video ↗, Remove Audio ↗ or Video to MP3 ↗ without saving in between.
Frequently asked questions
Will the compressed file still be an MP4?
Yes, with H.264 video and the original audio copied unchanged, unless you pick VP9 or AV1 in Advanced, which produce WebM.
How much smaller will my MP4 get?
Phone and camera recordings: typically 50–70% smaller at Balanced with no visible change. Files that were already exported from an editor or downloaded from a streaming service: often not much, and the estimate line will say so.
Does it work with MP4s from an iPhone?
Yes. iPhone MP4 and MOV files, including HEVC ones, are decoded natively in Safari, Chrome and Edge. Firefox on Windows may lack HEVC decoding.
Is there a limit on file size or length?
No. The input is read in place and the output streamed to disk. Gigabyte-scale files work; they just take longer.