Compress a video to a file size you choose, in your browser. A target size is not a wish — it is a bitrate, and bitrate times duration is the size exactly. Once that is fixed the only question left is whether the picture survives it, and that has a number too: bits per pixel per frame, shown before anything is encoded.
Step by step
01Add the clip
Drop an MP4, MOV, WebM or MKV. It is decoded by this page using the browser's own codecs — nothing is uploaded and there is no queue.
02Choose the size you need
Set the target in megabytes — usually because something has a limit: 8MB for Discord, 25MB for most email. The bitrate follows from it arithmetically.
03Read whether it will survive
The plan shows bits per pixel per frame for your settings. Above about 0.12 typical footage looks clean; below 0.06 it blocks and smears.
04Take the suggestion if it offers one
When the target is too small for the resolution, the tool names a height that would carry it and offers one click to apply. Then compress and download.
Worked example
The everyday case, and the choice that most compressors make badly on your behalf.
Given
The same 8MB, spent two ways
Keep 1080p
bitrate 1.00 Mbps
bits/pixel 0.016 -> blocks and smears
Scale to 480p
bitrate 1.00 Mbps (unchanged)
bits/pixel 0.081 -> holds together
Same file size. Five times the data per pixel.Both files are 8MB. One is a mush of blocks at full resolution, the other is a sharp smaller video. Most compressors give you the first without mentioning the second exists.
Why this one
A target size is a bitrate
Bitrate times duration equals size. So asking for 8MB from a 60-second clip is asking for about 1.1 Mbps, and there is no estimating involved — the tool derives it, subtracts the audio track and a couple of percent for container overhead, and tells you the number.
Bitrate alone does not predict quality
2 Mbps is generous at 480p and starved at 4K, which is why a bitrate on its own tells you nothing. Bits per pixel per frame — bitrate divided by width times height times frame rate — is the figure that does, and it is the one every other compressor hides behind a quality slider.
Scaling down is usually the better trade
When a size limit is tight, most tools lower quality and hand back a blocky video at full resolution. Halving the height quarters the pixel count, so the same bitrate gives four times the data per pixel. The tool works out which height would carry your target and offers it in one click.
Trimming beats compressing
Because size is bitrate times duration, removing seconds removes bytes at no cost to the picture at all. If half the clip is not needed, cut it first and you may not need to compress at all.
The thresholds are rules of thumb
0.12 and 0.06 bits per pixel are where typical mixed footage looks clean and where it starts to break. A static talking head survives far below that; fast handheld motion through foliage needs more than either. Treat the verdict as a strong prior, not a measurement of your specific clip.
The judgement call
Three ways to fit a size, suited to different footage.
The plan says blocky and offers a height
Scale down
Halving the height quarters the pixel count, so the same bitrate delivers four times the bits per pixel. A smaller sharp video beats a large mushy one at the same file size, nearly always.
A screen recording or a slide presentation
Halve the frame rate
Static content barely changes between frames, so 15fps looks almost identical to 30 and hands every remaining frame twice the data. Do not do this to handheld footage or sport.
The clip is mostly someone talking
Keep resolution, lower the size
A static frame compresses far better than the thresholds assume — they are set for typical mixed footage. A talking head often survives well below 0.06 bits per pixel.
Only a few seconds matter
Trim first
Size is bitrate times duration, so halving the length halves the size at no quality cost at all. Cutting is always cheaper than compressing.
The target is bigger than the source
Do nothing
Re-encoding an already-compressed video always loses detail. Producing a larger file that looks worse is the one outcome with nothing to recommend it, and the tool says so rather than proceeding quietly.
Reference
FAQ
Set the target to 8MB. The tool works out the bitrate that produces it and tells you whether your resolution can carry it — for a minute of 1080p it usually cannot, and it will offer a height that can. Scaling to 480p at the same 8MB gives each pixel about five times the data.
No. The clip is decoded and re-encoded by this page using the browser's own codecs, the same ones the video player uses. Nothing is uploaded, there is no queue, no watermark and no size limit beyond your own memory.
Because the bitrate the target size allows is too low for the number of pixels being encoded. Every frame has a fixed budget, and spreading it across two million pixels leaves too little for each one. The fix is almost always to reduce the resolution rather than accept lower quality at full size.
There is no single answer, which is the point — it depends on frame rate and content. As a working figure, 1080p30 wants roughly 7-8 Mbps to look clean and holds together down to about 3-4. Rather than memorising numbers, watch the bits-per-pixel figure: above 0.12 is comfortable, below 0.06 is trouble, at any resolution.
Within a few percent. The encoder targets an average bitrate rather than hitting a byte count exactly, so short clips in particular can land slightly over or under because container overhead is proportionally larger. The tool reports the real figure against the request once it has run.
Only for static content. Halving the frame rate hands every remaining frame twice as many bits, which is a clear win for screen recordings and slides. On handheld video or anything with real motion it produces visible judder, and the quality gained is not worth it.
Those with WebCodecs encoding: Chrome and Edge from 94, Firefox 130 on desktop, and Safari 26. The page says plainly when your browser cannot, rather than failing partway through an encode.
Keep going
Trim video
Cut the clip first — removing seconds removes bytes at no cost to the picture.
Video to GIF
See what a GIF costs against the same seconds as video.
Remove audio from video
Drop the soundtrack without re-encoding a single frame.
Image compressor
The same idea for stills — compress to an exact file size.