Reduce the size of an MP4, MOV or other supported video. Choose a quality level or a file-size target and download an MP4. Your video stays on your device.
Convertlo is a free online video compressor for MP4, MOV, MKV, WebM and AVI. Choose a quality level or a target size, then check the finished MP4 before sharing. Nothing is uploaded and the result has no watermark.
The tool tries WebCodecs, then a MediaRecorder-based real-time encoder, then FFmpeg in WebAssembly. Browser support and clip length affect speed. The software path can download its encoder before starting.
Choose To a file size and pick 10 MB, 20 MB, 25 MB or another target. The estimate uses your clip length and reserves space for audio and the MP4 container. If a pass is too large, the encoder can retry at a lower bitrate.
Enforce upload limit is on by default in size mode. It counts 1,000,000 bytes per MB and offers a download only when the finished MP4 fits. If it still exceeds the cap, shorten the clip, lower the resolution or remove audio. Uncheck the option for the previous binary target scale (1,048,576 bytes per displayed MB) and the option to download an over-target result.
Formats, settings and limits of this browser compressor.
| Capability | Supported | Detail |
|---|---|---|
| Input | ||
| MP4, MOV, MKV, WebM, AVI, M4V | Yes | Codec support depends on the browser and available encoder. |
| File size limit | No | No fixed server quota. Device memory and browser limits apply. |
| Long clips | Yes | Long clips depend on device memory, codec support and encoding speed. |
| Several videos at once | No | One clip at a time; the encoder wants the whole device. |
| Controls | ||
| Target file size | Yes | Name a size and the output is measured against it. |
| Quality levels | Yes | Light, Balanced, Strong, Extreme. |
| Resolution downscale | Yes | 1080p, 720p or 480p, or keep the original. |
| Remove the audio track | Yes | A checkbox; useful when a target is tight. |
| Compress more | Yes | One more real step on the same clip, after a weak result. |
| Trimming | No | Use our video trimmer first, then compress. |
| Frame rate control | No | The tool chooses how to handle frame rate. |
| Crop, rotate or filters | No | Use a separate editor for cropping, rotation or filters. |
| Output | ||
| MP4, H.264 video, AAC audio | Yes | H.264 MP4 output with AAC where audio is supported. |
| Guaranteed smaller output | No | Results depend on the source and encoder. Compare the displayed sizes. |
| WebM, AV1, HEVC or GIF out | No | The compressor produces H.264 in MP4. |
| Watermark | No | Nothing is added to the picture. |
| How it runs | ||
| Nothing is uploaded | Yes | The clip is encoded on your device and never sent anywhere. |
| Signup or daily limit | No | There is no account and no quota. |
| Offline use | No | The page loads from the network; the software fallback also fetches an engine. |
| API | No | This is a page, not a service. |
| Where | What to check | How to start |
|---|---|---|
| Discord | Discord documents 20 MB for non-Nitro users and mentions experiments. Check your account. | Try a 10 MB target if you need a smaller file, or set a target below the cap you see. |
| Check the limit for sending as a video or a document. | Choose a target below the cap for the send method you’ll use. | |
| Personal Gmail allows 25 MB of attachments. Other providers and work accounts can differ. | Leave room for other attachments. Check the finished file before sending. |
Platform guidance checked 5 November 2026. See the guides for Discord video compression, WhatsApp video compression and email attachments.
Try Light with Original resolution when detail matters. Balanced is a starting point for sharing. Strong and Extreme can reduce detail, especially on fast motion, small text and textured backgrounds.
Lower the resolution to 720p or 480p when you have a tight limit. Shorten unused footage with the video trimmer or remove audio if you don’t need it. Compare the actual size and play the result before sending.
We encoded three synthetic 8-second MP4 clips in Chromium using this tool’s FFmpeg software fallback. The table reports the actual downloaded bytes. These results depend on the source clip and encoder.
| Example | Settings | Original | Compressed |
|---|---|---|---|
| Portrait camera-style clip | Strict 1 MB, 480p | 4,124,031 bytes 540 × 960 | 926,720 bytes 270 × 480 |
| Screen-style clip with text | Balanced, original resolution | 223,901 bytes 1280 × 720 | 52,679 bytes 1280 × 720 |
| Fast-motion clip | Strict 2 MB, 480p | 8,789,009 bytes 1280 × 720 | 1,915,622 bytes 854 × 480 |
Your video is processed in the browser and the MP4 is created on your device. The page, analytics and ads can use the network, and the software encoder can require a download.
For long clips, a desktop encoder such as HandBrake can give you more control over codecs and rate settings. This tool is for quick browser compression with quality and target-size controls.