Video Compressor — Reduce Video File Size Online, No Upload
Shrink MP4, MOV or WebM videos to a quality level or a target size like 10 MB for Discord. H.264 MP4 output, processed on your device.
Found a problem, or something that could be better? We read every message and we fix things quickly.
This video compressor reduces the file size of MP4, MOV, WebM and MKV videos in your browser, so a clip that is too big for Discord, WhatsApp or an email attachment can be sent without uploading it to a conversion site first. Pick a quality level, or pick a target size and the tool works out the bitrate needed to land under it from the video's length. The output is an H.264 MP4, the format every phone, browser and chat app plays.
Everything runs on your device with ffmpeg and the x264 encoder compiled to WebAssembly. That keeps private videos private and removes upload waits and size caps, but it is slower than a server: WebAssembly encodes on one CPU core, so expect something like real time to a few times slower for 720p–1080p footage. Lowering the resolution is the biggest speed and size win. The first run downloads the ffmpeg engine (about 32 MB), which is cached for next time.
How to use
- Drop a video onto the box or click to choose one.
- Choose By quality for the best result at a reasonable size, or To a file size and pick the limit you need to fit.
- Leave Resolution on Auto (it suggests a lower resolution when the target is tight), or set it yourself.
- Pick an audio bitrate, or remove audio for silent clips.
- Click Compress video, keep the tab open while it encodes, then compare the before/after size and download the MP4.
Frequently asked questions
How do I compress a video to under 10 MB for Discord?
Choose To a file size, pick Discord (10 MB) and compress. The tool divides the budget by the video's duration to get a total bitrate, subtracts the audio bitrate, and aims about 7% under to leave room for MP4 overhead. For a 60-second clip that is roughly 1.2 Mbps of video, which looks fine at 720p but blocky at 1080p, so Auto resolution drops to 720p or 480p as needed. If the result still overshoots, it re-encodes once at a lower bitrate.
Does compressing a video reduce quality?
Yes, re-encoding is lossy, but how much you notice depends on the settings. The High preset (x264 CRF 23, x264's own default) is hard to tell apart from most phone footage while often halving its size, because phones record at high bitrates for speed. Each +6 on the CRF scale roughly halves the file size, which is the step between the presets here.
Why is compression slow compared with other sites?
Other sites upload your file and encode it on servers with many cores. Here the encoding happens on your own computer in WebAssembly, on a single thread, so a long 1080p video can take several minutes. The trade is that nothing is uploaded and there is no size cap or queue. To speed it up, lower the resolution or choose the Faster encoder setting.
What is the WhatsApp video size limit?
WhatsApp limits videos sent as media to 16 MB and compresses them heavily itself. Compressing to just under 16 MB here first gives you control over how it looks. Sending the file as a document instead allows much larger files (up to 2 GB) without WhatsApp re-compressing it.
Which format is the compressed video?
MP4 with H.264 video and AAC audio, with the index moved to the front of the file (faststart) so it starts playing before it is fully downloaded. That combination plays on every current phone, browser, TV and editing app, which matters more than the slightly better compression of newer codecs like H.265 or AV1.
Is there a file size limit?
There is no limit set by this tool, but the browser has to hold the output in memory, and WebAssembly memory is capped at a few GB. Files of several hundred MB generally work on a desktop; a multi-GB 4K file may run out of memory, in which case trim it first with the video trimmer.
Quality or target size: which to use
Quality mode (CRF) keeps the visual quality constant and lets the size fall where it falls: a static talking-head clip comes out tiny, a fast sports clip larger. Use it when you just want a smaller file that still looks good.
Target-size mode does the opposite: it fixes the size and accepts whatever quality that buys. Use it when a hard limit decides, such as an upload form or a chat app. The maths is simple: bitrate (kbps) = size (MB) × 8,000 ÷ duration (s). A 25 MB budget for a 2-minute video is about 1,670 kbps total, so roughly 1,540 kbps video plus 128 kbps audio.
Rough bitrate guide for H.264
What a given video bitrate looks like depends on motion and detail, but as a starting point for 30 fps footage:
• 1080p: 4–8 Mbps looks good; under 2.5 Mbps it starts to smear in motion.
• 720p: 2–4 Mbps looks good; usable down to about 1 Mbps.
• 480p: 1–2 Mbps; usable down to about 500 kbps.
• 360p: 400–800 kbps; fine for small previews.
If the bitrate the target size allows sits below the range for the current resolution, a smaller resolution at that bitrate will look better than a blocky large one. That is what Auto resolution does.
Common upload limits (2026)
• Discord: 10 MB per file without Nitro; 50 MB with Nitro Basic; 500 MB with Nitro.
• WhatsApp: 16 MB for videos sent as media; up to 2 GB as a document.
• Gmail: 25 MB of attachments per email (larger files are turned into Google Drive links).
• Outlook.com: 20 MB of attachments for most accounts.
Limits change; check the service if you are close to one.
Related free tools
- Video Trimmer — Cut the start and end off a video on a frame preview. Fast lossless cut or exact re-encode, mute, and reframe to 9:16, 1:1 or 4:5.
- Video to GIF — Turn an MP4, MOV or WebM clip into a palette-optimised GIF. Trim on a preview, set width, fps and looping. Nothing is uploaded.
- Image Compressor — Shrink images by quality or to a target size, optionally cap the dimensions, and download smaller JPG or WebP files. Batch, in your browser.
- Video to MP3 — Extract the audio from a video as MP3, M4A, WAV, or the original stream without re-encoding. Fast, private, in your browser.