Video Compressor
Shrink a video to an exact size in MB or to a quality level, with the bitrate worked out for you.
- Free
- No sign-up
- No watermark
- Runs in your browser
Loading the tool.
What bitrate a file size leaves you
A compressed file weighs its bitrate multiplied by its length, so a size limit is really a bitrate limit. Divide the target by the duration, take off the audio, and what remains is all the picture gets. The longer the clip, the thinner that share, which is why a long video needs a smaller frame to stay sharp.
| Clip length | 8 MB target | 25 MB target | 50 MB target |
|---|---|---|---|
| 30 seconds | 2,005 kbps | 6,539 kbps | 13,205 kbps |
| 1 minute | 939 kbps | 3,205 kbps | 6,539 kbps |
| 3 minutes | 228 kbps | 983 kbps | 2,094 kbps |
| 10 minutes | None: the audio alone is 9.6 MB | 205 kbps | 539 kbps |
Each cell is target size × 8 ÷ clip length − 128 kbps, with 1 MB = 1,000,000 bytes and the container ignored; 10 minutes of 128 kbps audio is 128,000 × 600 ÷ 8 = 9.6 MB. The compressor also sets aside 1% plus 16 KB for the MP4 container and aims 4% under your target, so it picks a slightly lower bitrate, and it drops the audio to 96 kbps when 128 would take over a quarter of the budget. Rule of thumb for H.264 at 30 fps, not a measurement: about 1 Mbps looks clean at 480p, 2.5 Mbps at 720p and 5 Mbps at 1080p; talking heads need less, fast motion more. The tool only warns below its own Low preset, which is 1.5 Mbps at 1080p and 30 fps.
How it works
Drop in the video. Choose a file or drag it onto the box. The tool reads its length, frame size and codecs from the file's header, so this takes a moment even for a long recording.
Pick a size or a quality. Target size offers 8, 25 and 50 MB or a number you type, and shows the bitrate that leaves for the picture, with a warning when it will look poor. Quality offers High, Medium and Low with an estimate of the result. Cap the resolution at 1080p, 720p or 480p, whichever is smaller than your video, for a smaller frame.
Compress and compare. The video is re-encoded to H.264 with AAC audio in an MP4. When it finishes you see the old size, the new size and the share you saved. If the encoder overshot your target, one click tries again at a bitrate lowered by the measured miss, unless that would starve the picture, in which case you are told what to change instead.
What you get
- The bitrate is calculated, not guessed
- Type 5 MB and the tool divides it by your clip's length, reserves room for the audio and the MP4 container, and hands the encoder the bitrate that fits.
- Hopeless targets are caught before encoding
- When a size leaves too few bits for your frame, you are told before anything runs and, when a lower resolution would make that size work, which one.
- Misses are reported, not hidden
- Encoders treat a bitrate as an average, so busy footage can land a little over. The result says by how much, and the retry scales the bitrate down by that measured overshoot instead of guessing, or says plainly when going lower would ruin the picture.
- Caps that respect vertical video
- The 1080p, 720p and 480p caps apply to the short edge, so a phone clip capped at 720p comes out 720×1280 rather than squeezed into a landscape frame. Nothing is ever scaled up.
Questions people ask
How do I compress a video on my phone?
Open this page in your phone's browser, tap the box and pick the clip from your gallery; the compression runs on the phone itself. It needs a browser with WebCodecs and an H.264 encoder, such as recent Chrome on Android or Safari 26 or newer on iPhone, and if either is missing the tool says so before you choose any settings. A lower resolution cap leaves the phone fewer pixels to encode on a long clip.
Can I compress a video without losing quality?
Not entirely: any re-encode loses a little, because the new encoder only sees the decoded frames of the old one. How much depends on the bits per second left for the picture compared with how busy the footage is: a calm talking-head shot holds up at a far lower bitrate than handheld action, which turns soft and blocky first. Start from the best copy you have, and lower the resolution before you squeeze the bitrate.
What format does the compressed video come out in?
An MP4 with H.264 video and AAC audio, the pairing nearly every phone, browser, editor and upload form accepts. The input can be MP4, MOV, WebM or MKV, and a file without sound comes out without sound.
Why is the compressed file slightly bigger than the size I picked?
Because an encoder treats the bitrate as an average across the clip, not a hard ceiling: busy scenes and the first keyframe take extra bits, and at very low bitrates it often cannot go as low as asked. The tool aims 4% under your target to absorb that. If the file still lands over, you see by how much and can run a second pass cut by that overshoot, unless it would drop below what the frame size can hold; then a lower resolution or a larger target is the way.
How long does it take to compress a video?
Roughly as long as it takes your device to decode and re-encode every frame, so it grows with the length and the frame size. In our runs in desktop Chrome, a 19.6-second 1080×1920 phone clip took 10 to 12 seconds to compress to 5 MB at full size, and about 5 seconds with the 720p cap.
Should I lower the resolution or the bitrate?
Lower the resolution when the target is tight. The same bitrate spread over fewer pixels gives each pixel more detail, which is why the tool suggests a cap when a size would look poor at full resolution. Keep the original frame when the bitrate is already comfortable for it.
Can I compress confidential footage with this?
Yes. The video is decoded and re-encoded by your own browser, and neither the original nor the smaller copy is sent to us or to anyone else, so client work and unreleased footage stay on your machine.
The smallest file is a shorter video
This compressor keeps every second you give it. GPT-Video does the opposite on purpose: it watches a long recording, finds the moments worth posting and cuts them into short vertical clips, which are small because they are short.
Related
Your file is processed on your device and never uploaded.