Free online video compressor — compress video in your browser
Drop in an MP4, MOV, MKV or WebM and make the video smaller without uploading it anywhere. Set a target size in megabytes or pick a quality level — either way, your file never leaves your device.
Drop your video here
or click to browse — MP4, MKV, MOV, WebM, AVI and more
Compress video online without uploading a single byte
Almost every free video compressor online works the same way: you upload your file, a server encodes it, and you download the result. That means a copy of your video sits on somebody else's disk, and you queue behind everyone else using the service.
This one is different. smaller.video runs FFmpeg — the encoder behind most of the video on the internet — compiled to WebAssembly and executed inside your own browser tab. Choosing a file does not start an upload; it hands the bytes to a decoder running a few centimetres away on your own CPU. There is no queue, no file size cap beyond your device's memory, and no copy of your video anywhere but your disk.
That makes it a reasonable way to reduce video file size for footage you would not want to hand to a stranger: client work, medical or legal recordings, internal meetings, anything under NDA. It also makes it usable offline once the engine is cached.
How to compress a video in your browser
Four steps. No account. No waiting in a queue.
Choose your video file
Drag an MP4, MOV, MKV, WebM, AVI, WMV or FLV onto the drop zone. Nothing is transmitted — the browser just reads the file into memory.
Pick a target size or a quality level
Type a ceiling in megabytes and the bitrate is solved for you, or use the quality slider to aim a fraction below the source bitrate. Optionally scale the resolution, shrink the audio, or change the output container.
Trim it if it is longer than it needs to be
Drag the start and end handles to keep only the part you need. Size is bitrate multiplied by duration, so cutting length is often the only way to hit a tight ceiling without wrecking the picture.
Download the smaller video
FFmpeg encodes locally and reports live progress, and you can cancel a run at any point. When it finishes you get a preview and a download — the compressed video is already on your machine.
Want the full technical walkthrough? See how browser-based video compression works.
How to make a video smaller without wrecking it
There are only three levers that meaningfully reduce video file size, and they are worth pulling in this order.
1. Lower the bitrate first
Bitrate is the number of bits spent per second of video, and it dominates file size. The quality slider here targets a fraction of your source bitrate — roughly 78% at the gentlest end, about 20% at the most aggressive. On talking heads, screen recordings and slide decks you can usually halve the bitrate before anything is visible. On film grain, confetti, sports and fast pans, back off. Read what video bitrate actually controls.
2. Drop the resolution to what will actually be watched
720p has about 44% of the pixels of 1080p, and 1080p has about a quarter of the pixels of 4K. If the video is going into a 640-pixel-wide column on a web page, encoding it at 4K is spending most of your file on detail nobody will see. Scale it down and the bitrate you need falls with it.
3. Deal with the audio last
Audio is a small share of most video files, but on a long, low-bitrate clip it stops being negligible. A stereo track carrying identical channels — common in screen recordings and conference calls — can be compressed or stripped outright with the audio setting. More techniques for shrinking a video without visible quality loss.
If you only need a different container — an MKV that has to become an MP4, for example — use Remux instead. It rewrites the wrapper and copies the video stream untouched, so it finishes in seconds and loses nothing. See which video formats are supported.
Compress video to a specific file size
Most people arrive here with a number rather than a preference: something rejected their file and named a limit. That is an arithmetic problem, not a taste problem. Switch the encoder to Target size, type the ceiling in megabytes, and the bitrate is solved from the length of your clip before anything is encoded.
The tool then does the part that separates a target from a guess: it measures the finished file, and if the encoder overshot it scales the bitrate by exactly how far over it landed and runs again. Each of these pages opens the compressor with that ceiling already set and shows what fits inside it at every clip length.
- Compress to 5 MB The tightest ceiling here. Past about three minutes it stops being possible at all.
- Compress to 8 MB The classic chat and forum attachment wall. Tight enough that duration decides everything.
- Compress to 10 MB The default cap on a huge number of upload forms — and 25% more room than 8 MB.
- Compress to 16 MB The WhatsApp video ceiling — and the one target where the platform re-encodes after you.
- Compress to 20 MB The default in helpdesks, CMS media libraries and upload widgets. Rarely announced.
- Compress to 25 MB The Gmail attachment limit — with the base64 overhead that makes 25 MB less than it looks.
- Compress to 50 MB Roomy enough that 1080p survives on short clips. The first target that stops hurting.
- Compress to 100 MB Generous enough for real 1080p. Also GitHub's hard per-file push limit.
- Compress to 200 MB Big enough that the real question is your viewer's patience, not the platform's limit.
- Compress to 500 MB Discord Nitro's per-file ceiling, and the point where the browser becomes the bottleneck.
Any other number works too — the presets are shortcuts, not the whole range. See how the size targets compare, or run the arithmetic yourself.
How long the clip is decides what is possible
This is the part that surprises people. A 4 GB source and a 40 MB source compress to almost the same size at the same settings, if they are the same length — because file size is bitrate multiplied by duration, and the compressor controls the bitrate. What the source weighed on the way in barely matters.
So the real question is never "how big is my file", it is "how many seconds do I have to spread my budget across". Here is what a minute of video costs at bitrates that hold up on ordinary footage.
| Resolution | Workable bitrate | Per minute | Per 5 minutes |
|---|---|---|---|
| 360p | 500 kbps | 4.6 MB | 23 MB |
| 480p | 1,000 kbps | 8.3 MB | 41 MB |
| 720p | 2,500 kbps | 19.2 MB | 96 MB |
| 1080p | 5,000 kbps | 37.6 MB | 188 MB |
| 4K | 18,000 kbps | 132.8 MB | 664 MB |
Read it in whichever direction is useful. Five minutes of 1080p is around 190 MB at a bitrate that looks genuinely good, so a 25 MB email limit and a five-minute 1080p clip are not compatible at any setting — you drop to 480p, you trim, or you send a link.
The numbers are conservative on purpose. Screen recordings, slide decks and talking heads survive far lower bitrates than these, because most of the frame is identical from one moment to the next and the encoder can describe a whole second in very little. Sport, film grain, confetti and handheld footage of moving water all need more.
Compressing for Discord, WhatsApp and email
Platforms differ in more than their limits, and the differences change what you should actually do. Some re-encode whatever you send them, which inverts the usual advice: you want to hand over the best quality that fits rather than the smallest file you can make.
Discord
The free upload ceiling has changed over the years, so check it by attempting the upload rather than trusting a number. Gameplay clips are the hardest content there is to compress — the whole frame moves, and capture software records at generous bitrates — so drop to 720p before touching anything else. Full Discord guide.
Around 16 MB through the media picker in most regions, and WhatsApp re-compresses whatever you send. That means compressing gently to the top of the budget rather than as far as it will go, or sending the video as a document to skip the second encode entirely. Full WhatsApp guide.
Email — Gmail and Outlook
Gmail sends up to 25 MB and Outlook.com around 20 MB, but attachments are base64-encoded in transit and grow by about a third, and many receiving servers apply their cap to the encoded size. Target 18–20 MB for an unknown recipient. Full email guide.
Anything else with a number attached
Upload forms, learning platforms, ticketing systems and code hosts all publish their own ceilings — GitHub blocks any single file over 100 MB on push, for instance. The method is the same whatever the number: set it as the target, aim about 10% under it, and let the bitrate be solved. Pick a ceiling.
Which video formats can you compress?
Input is essentially anything FFmpeg can read — MP4, MOV, MKV, WebM, AVI, WMV, FLV, 3GP and more. Output is MP4, MKV, WebM or MOV. What is worth doing to a file depends on what is already inside it, so each format has its own page.
- Compress MP4 The universal container. Usually already H.264, so the gains come from bitrate and resolution.
- Compress MOV iPhone and QuickTime recordings. Frequently HEVC or ProRes, and frequently huge.
- Compress MKV Long recordings, rips and archives. Big enough that upload-based tools often refuse them.
- Compress WebM Already efficient — so the realistic gains are smaller, and worth understanding first.
- Compress AVI Legacy codecs, dramatic savings. Read in, MP4 out.
- Compress WMV Old Windows exports. Nothing plays them now, and remuxing is not an option.
- Compress FLV A dead container, often with a perfectly modern video inside. Try remux first.
- Compress M4V Apple's MP4 under another name. Renaming it often solves the whole problem.
- Compress MTS / M2TS AVCHD camcorder footage. Enormous, usually interlaced, and split into 2 GB pieces.
If the file only needs a different wrapper — an MKV that has to become an MP4 so a browser will play it — use Remux. It copies the video stream untouched and rewrites the container, so it finishes in seconds and loses nothing. The format reference covers what plays where.
Why use a browser-based video compressor
Everything runs locally. Your file never touches a server.
Nothing is uploaded
Your video is never sent to any server. FFmpeg runs in your browser via WebAssembly, so the bytes never leave the tab.
No account needed
Open the page, compress the video, download it. No sign-up, no email, no billing, no free-tier countdown.
Compress MP4, MOV, MKV and WebM
Output to MP4, MKV, WebM or MOV. Input accepts virtually any container FFmpeg can read, including AVI, WMV, FLV and 3GP.
Full control of the trade-off
Set the quality target, the output resolution, how the audio is handled, which codec does the encoding, and where the clip starts and ends. Or leave the defaults alone — they are remembered for next time.
Genuinely free
No watermark, no paid tier and no file size limit beyond what your device can hold in memory.
Real FFmpeg, not an approximation
The same encoder that ships inside VLC and processes video across the internet, compiled to WebAssembly and running locally.
None of that makes it the right tool for every job. A desktop application is faster and far more capable, and for large or repeated work you should use one — here is the honest comparison with HandBrake, and with the FFmpeg command line.
Video compression guides
The settings above make more sense once you know what they do. These guides explain the model the tool is built on.
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What CRF value should you use? A practical guide
What CRF means in x264 and x265, which values are worth using, why the two scales are not comparable, and when a bitrate target is the better tool.
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The Discord file size limit, and every way around it
Why Discord caps uploads, how to find your real limit, and the four workarounds that work: compressing properly, trimming, linking and Nitro.
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H.264 vs H.265: the real file size difference
How much smaller H.265 really makes a file, why the 50% figure is optimistic, what it costs in encode time, and when H.264 is still the right answer.
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Why are iPhone videos so big? HEVC, 4K and ProRes
Apple's own storage figures per recording mode, what HEVC and ProRes do, why the files will not open on Android, and how to make them smaller.
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How much of your video file is audio?
Audio costs the same per minute whatever the resolution, so its share grows as the video shrinks. What each format costs in megabytes, and when to strip or downmix.
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Screen recordings are a different compression problem
Why the usual advice to downscale is wrong for screen capture, what frame rate really costs, why red text smears, and the settings that keep code readable.
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Why your video won't play: containers, codecs and compatibility
The difference between a container and a codec, how to read the error you are getting, and why a remux fixes most playback problems without touching quality.
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How to trim a video to fit a size limit
File size is bitrate times duration, and duration is the term nobody treats as a setting. What a second of runtime costs, and where to cut without re-encoding.
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FFmpeg in the browser: how WebAssembly makes it possible
How FFmpeg ends up running inside a browser tab: the WebAssembly build, the in-memory filesystem, and why SharedArrayBuffer needs COOP and COEP.
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How to compress video for the web
How to reduce video file size for the web: which codec to use, what CRF to set, when to downscale, and the settings for email, embedding and uploads.
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How to reduce video file size without losing quality
How to cut video file size without visible quality loss: CRF values by content type, when to downscale, audio savings, and encoder preset trade-offs.
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What is video bitrate and why does it matter?
What bitrate actually controls, how it drives file size and quality, the difference between CBR, VBR and CRF, and how to pick the right number.
Video compressor FAQ
The questions people ask before they trust a tool with a video file.
Is this video compressor really free?
Yes. There is no paid tier, no watermark, no sign-up and no per-file limit. The site costs almost nothing to run because your browser does all of the encoding work — there is no server farm to pay for.
Does my video get uploaded anywhere?
No. The file is read from your disk into browser memory and handed to FFmpeg compiled to WebAssembly, which runs inside the page. No part of the video is ever sent over the network.
How much smaller will my video get?
The quality slider sets the fraction of the source bitrate to target, from about 78% at the gentlest position down to about 20% at the most aggressive. The default sits near 56%, so a typical 1080p clip roughly halves. The tool works the number out from your file and shows it before encoding. Dropping the resolution as well compounds the saving.
Why does the first compression take a while to start?
Before it can encode anything the page downloads roughly 30 MB of FFmpeg compiled to WebAssembly. Your browser caches it, so every compression after the first starts straight away.
Can I compress a video to an exact file size?
Yes. Choose Target size, type a ceiling in megabytes, and the bitrate is solved from the length of your clip. The tool then measures the finished file and re-encodes at a corrected bitrate if the first pass came in over, so the ceiling is a limit rather than a suggestion.
What is the maximum file size I can compress?
There is no service-imposed limit, because no service is involved. The whole file is held in your browser's memory while it is encoded, so the ceiling is your own device: a desktop with plenty of RAM manages several gigabytes, a phone manages far less.
Which video formats are supported?
Input is essentially anything FFmpeg can read, including MP4, MOV, MKV, WebM, AVI, WMV, FLV and 3GP. Output is MP4, MKV, WebM or MOV. MP4 with H.264 is the right answer unless you have a specific reason to pick something else.
Is there a watermark or a sign-up?
Neither. There is no account, no email capture, no free-tier countdown and nothing added to your video. The site is cheap to run precisely because your browser does the encoding, so there is nothing to recoup.
Does it work offline?
Yes, once the FFmpeg WebAssembly binary has been cached. Load the page with a connection, then disconnect, and compression still works start to finish — which is also the simplest way to prove nothing is being uploaded.
Will compressing lose quality?
Any re-encode discards information; the question is whether you can see it. Footage exported at a generous default bitrate usually survives halving without anything visible. The exception is Remux, which copies the video stream untouched into a new container and is genuinely lossless — but does not make the file smaller.
Why is my video still too big after compressing?
Almost always because it is long. File size is bitrate multiplied by duration, and duration is not a setting. If a ten-minute clip will not fit in 10 MB at any resolution, the answer is to trim it rather than to compress harder.
Can it convert HEVC or H.265 to H.264?
Yes, and that is often the real reason to compress an iPhone recording. Output to MP4 with the codec left on H.264 and the video is re-encoded into the one format that plays on hardware which cannot decode HEVC at all. The codec control also lets you go the other way and write H.265, which is a reasonable choice for your own archive and a bad one for anything you are sending to a stranger.