Video tools
Compress MP4 files
MP4 is the format almost every phone, browser and chat app plays. This tool turns heavy MP4 and MOV files into lighter MP4s that behave well when you share them.
An MP4 that opens cleanly everywhere
Encoders that use B-frames can leave the video track starting a few hundredths of a second after the audio. Some chat and document apps then show a black cover image or a short blank at the start. Delivery MP4s from this tool are muxed so the video starts at time zero, and the check before download confirms the first frame matches your original.
Files are written with the index at the front (fast start), so playback begins before the whole file has downloaded.
What goes in, what comes out
- In: MP4, MOV, MKV, AVI, WebM, MXF, MTS and other common video containers.
- Out: an H.264 MP4 for delivery. AAC audio at a modest bitrate is copied as is; other audio is converted to 192 kbps AAC.
- Duration and the first frame are verified against the source, and the video must start at time zero.
Why your MP4 is large
File size is bitrate times duration. Phones and cameras record at high bitrates so that editing and colour work stay clean; those rates are far above what playback needs. A 4K clip from a phone can run at several times the bitrate a viewer could ever tell apart from a lighter version. Reducing that surplus is where almost all the savings come from.
| Compress MP4 | |
|---|---|
| Duration | Same, verified |
| Audio | Copied when it is standard AAC, otherwise converted to AAC |
| Frame rate | Same |
| Picture size | Same up to 1080p; larger sources scaled down to fit 1080p |
| Bitrate | Lower, chosen per clip |
| First frame | Matches the original, verified |
Questions
Can I compress a MOV to MP4?
Yes. Upload the MOV; the result is an MP4 made for sharing.
Will the compressed MP4 play on iPhone and Android?
Yes. H.264 MP4 plays on every current phone, browser and chat app.
Does it work with variable frame rate phone clips?
Yes. The frame count and duration of the result are checked against the original.
Last updated 2026-10-07.