Compress MP4
A smaller MP4, made on your own device.
MP4 in, MP4 out. When you load a video, this page sets a target size computed from its resolution, frame rate and length. Tap 70%, 50%, 30% or 10% to aim for that share of the original instead, or click the After size and type a number in MB.
Free Video Compressor
No sign-up. No upload. No size limit.
Nothing is uploaded — the file is compressed on your device.
How the starting size is computed
An MP4 is a container. Inside it is a video stream (usually H.264, sometimes HEVC or AV1), an audio stream (usually AAC) and an index. The file size is mostly the video bitrate multiplied by the length.
This page gives the video a bitrate per pixel per frame. For MP4 (H.264) that works out to about 4 Mbps for 1080p at 30 fps, about 6 Mbps for 1080p at 60 fps and about 16 Mbps for 4K at 30 fps. Frames above 30 fps count half, because neighboring frames at high frame rates are more alike. The bitrate is never set higher than the source's own. So if your MP4 already uses less, the panel shows "At this setting the file stays about the same size." This is common for files exported from an editor or downloaded from a streaming site.
Compressing an MP4 here
Drop the file on the page or click to choose it. The Screen size list shows Original with its resolution and the lower steps; tap one to set the output resolution. If a size can only be reached at a lower resolution, the panel picks it itself, marks that row with a dashed amber frame and shows "Resolution set to W × H to reach this size."
Press Compress video. A progress window shows the percentage, elapsed and remaining time, and a Stop button; the screen is kept awake meanwhile. The output is written to disk as it is produced, so MP4 files of several GB work. When it finishes, the Compare tab shows original and result with a slider and 1- or 10-frame stepping. Download saves the new file; your original MP4 is not changed.
Format, audio and odd files
Under Advanced, Format lists MP4, MP4 · HEVC, WebM and WebM · AV1, but only the ones your browser can encode on this device. For the same resolution this page plans HEVC at 65% of the H.264 bitrate and AV1 at 55%. MP4 with H.264 is the default. Audio offers Keep as is, 128 kbps, 64 kbps and Remove audio. Only the first audio track is kept, and audio with more than 2 channels is mixed down to stereo when it is re-encoded.
On some Macs, Chrome stops decoding certain H.264 files partway through. The page then restarts with software decoding; frames that still cannot be decoded are replaced with the previous frame, and the result says how many. If you only need part of the clip, or only its sound, use Trim Video ↗, Remove Audio ↗ or Video to MP3 ↗.
Frequently asked questions
Will the compressed file still be an MP4?
Yes, unless you choose WebM or WebM · AV1 under Format. MP4 (H.264) is the default.
How much smaller will my MP4 get?
It depends on the source bitrate. The estimate row shows the expected size and the percentage that remains before you start. If it shows "At this setting the file stays about the same size", the MP4 already uses less than the bitrate this page would give it; pick 50% or a smaller share to force a smaller file.
Can it read MP4 files with HEVC video?
Only on devices with a hardware HEVC decoder. Chrome has no software HEVC decoder, so on a computer without one the page cannot read the file.
Is there a limit on file size or length?
This page sets none. Files of several GB work because the result is written to disk as it is made.
Compress MP4
Opens the compressor with a target size computed for this page.