How to compress an MP4
- Drop the MP4 files (or a folder) above.
- Pick what they are for — Discord, email, messengers, free up space — or set a size with the slider.
- Choose where to save them and click “Choose folder and compress” (or “Compress” once a folder is set).
The result is again MP4 with H.264 video and AAC sound, so it plays on Windows, Mac, iPhone, Android, smart TVs and in every browser. Need HEVC or AV1 for smaller files? Change the codec under Advanced settings.
Why some MP4 files are huge
MP4 is only a container — the size depends on the video inside. Phones and cameras encode in real time at high bitrates (40–100 Mbit/s for 4K). Screen recorders and video editors often export at “maximum quality” settings. Downloaded or messenger videos, on the other hand, are already squeezed and won’t get much smaller without lowering resolution.
Three ways to make an MP4 smaller
- Lower the bitrate — the main lever. The size slider does this directly.
- Lower the resolution — 4K to 1080p cuts the needed bitrate by about 60% with little visible loss on laptop screens.
- Use a more efficient codec — HEVC saves about 40% compared with H.264 at the same quality; AV1 about 50%.
CompressLab combines them automatically: with Resolution on “Auto” it lowers the resolution only when the bitrate would otherwise be too low for a clean picture.
Typical results
| Source | Original | After “Free up space” |
|---|---|---|
| iPhone 4K 30 fps, 1 min | ≈ 350 MB | ≈ 60–90 MB (4K) / 35–50 MB (1080p) |
| Android 1080p 60 fps, 1 min | ≈ 120 MB | ≈ 25–40 MB |
| Screen recording 1080p, 10 min | ≈ 400 MB | ≈ 30–60 MB |
| Zoom / Teams recording, 1 h | ≈ 300–700 MB | ≈ 100–200 MB |
Private by design
Most “compress MP4 online” sites upload your video to their servers. CompressLab runs the encoder inside your browser using your computer’s graphics hardware. Your file never leaves your device — useful for work recordings, family videos and anything under NDA.
Questions
How do I reduce the size of an MP4 without losing quality?
Use the “Free up space” preset: it keeps resolution and frame rate and uses a quality-based setting, so the result looks the same at a fraction of the size.
Is there a size limit for MP4 files?
No. Everything runs on your computer, so even 10 GB files work.
Does it add a watermark?
No. There is no watermark, no sign-up and no limit on the number of files.
Can I compress MP4 on a Mac?
Yes, in Chrome, Edge or Opera on macOS. Safari does not yet support everything needed.
Last updated: 2026-10-30