Compress a video to the size you need, right in your browser
This video compressor makes MP4, MOV, MKV and WebM files smaller without uploading them. Type the size you need in megabytes — 25 MB for an email, say — and it works out the bitrate, encodes, checks the result and encodes again at a lower bitrate if the first try is too big. Prefer to think in quality? Use the slider instead; the estimated size is shown before you start.
The work is done on your device by your browser’s video encoders (WebCodecs), driven by the open-source Mediabunny library (MPL-2.0). Choose MP4 with H.264 for the widest compatibility, HEVC or AV1 for smaller files, or WebM with VP9 or AV1. Formats browsers can’t decode, such as AVI, WMV or FLV, are first decoded with ffmpeg.wasm (GPL-2.0-or-later) — a 32 MB download that happens only when you agree.
How to use the Video Compressor
- Drop a video on the box or click to choose one. Its duration, resolution, frame rate, codecs and bitrate appear next to a preview.
- Choose Target file size and type a size in MB (or tap 8, 10, 16, 25, 50 or 100 MB), or choose Quality and move the slider.
- Optionally lower the Max resolution or Frame rate, and choose whether to keep, re-encode or remove the Audio.
- Pick the Output format and Video codec (codecs your browser can’t encode are marked ✕) and check the estimate.
- Press Compress video; the progress bar shows the time left and Cancel stops at any moment.
- Compare both versions side by side, then press Download.
Video Compressor features
Exact target size
The bitrate is worked out from the target, the audio and the duration. If a pass overshoots, it is corrected from the measured result and encoded again, up to four passes.
Quality mode with an estimate
The slider sets bits per pixel, adjusted for resolution, frame rate and codec, so you see the bitrate and likely size first.
Four codecs, checked first
Each codec is tested against your browser’s encoders at the chosen size, so an unsupported one is marked instead of failing halfway.
Never bigger than the original
If your settings would make a larger file, you are told to keep the original instead.
Lossless audio copy
AAC going into MP4 or Opus going into WebM is copied packet for packet.
Phone videos handled
Rotated clips stay upright; HDR clips are converted to standard dynamic range, and you are told before it happens.
How the target-size calculation works
Take a 3-minute clip that must fit in 25 MB with 128 kbps audio. 25 MB is 200,000,000 bits; aiming 3% lower for the container leaves 194,000,000. The audio uses 128,000 × 180 = 23,040,000 bits, leaving about 171 million for the picture — roughly 950 kbps. That is fine at 720p but thin at 1080p, so the tool warns you when the bitrate is too low for the resolution.
Encoders never hit a bitrate exactly, so after each pass the tool measures the bytes the video really took and scales the bitrate to match. The table shows the video bitrate common targets leave after 128 kbps of audio.
| Target size | 1-minute video | 3-minute video | 10-minute video |
|---|---|---|---|
| 10 MB | ≈ 1.2 Mbps | ≈ 300 kbps | Doesn’t fit — the audio alone is about 9.6 MB |
| 25 MB | ≈ 3.1 Mbps | ≈ 950 kbps | ≈ 195 kbps |
| 50 MB | ≈ 6.3 Mbps | ≈ 2.0 Mbps | ≈ 520 kbps |
| 100 MB | ≈ 12.8 Mbps | ≈ 4.2 Mbps | ≈ 1.2 Mbps |
Which codec and format should you choose?
The codec decides how efficiently the picture is stored; the format is the wrapper holding video, audio and timing. The percentages are the rule of thumb the quality mode uses. Browser encoders are tuned for speed, so they are a little less efficient than slow desktop encoders.
| Codec | Format | Bitrate for similar quality | Plays on |
|---|---|---|---|
| H.264 (AVC) | MP4 | Baseline | Practically every phone, computer, TV and app |
| HEVC (H.265) | MP4 | About 40% lower | iPhone, Mac, most Android phones, newer TVs; some Windows PCs need an add-on |
| VP9 | WebM | About 35% lower | All current browsers and Android |
| AV1 | MP4 or WebM | About 50% lower | Current Chrome, Edge, Firefox and Android; Apple devices with AV1 hardware |
Tips for the smallest file that still looks good
- Lower the resolution before squeezing the bitrate. 720p at 1.5 Mbps usually looks cleaner than 1080p at the same bitrate.
- Cap the frame rate at 30 fps for talks and screen recordings; keep 60 fps for sport and gameplay.
- Spend less on audio when the target is tight — speech sounds fine at modest bitrates.
- Trim first with Trim Video: every second removed is space for better quality.
- Email: Gmail Help gives a 25 MB attachment limit (bigger files become a Google Drive link), so aim a little under.
- Plan long recordings with the video bitrate calculator.
Video Compressor FAQ
How do I compress a video to a specific size?
Choose Target file size, type the size in MB and press Compress video. If the first result is over, it is encoded again at a corrected bitrate. 1 MB here is 1,000,000 bytes, so the file also fits limits that count 1,048,576 bytes per MB.
Does compressing a video reduce its quality?
Some detail is always lost, but at sensible settings it is hard to notice on a phone or laptop. Very low bitrates at high resolutions look worst, so lower the resolution instead.
Is this video compressor free and private?
Yes. No account, no watermark, no limit. Your video is encoded on your device and never uploaded; only the Mediabunny library (about 700 KB) is fetched from a CDN.
Why is HEVC or AV1 marked as unavailable?
Encoders depend on your browser, system and hardware. Chrome and Edge usually offer H.264, VP9 and AV1; HEVC encoding needs hardware support. Safari before version 26 can encode video but not audio, so audio must be kept as it is or removed.
Why did the tool tell me to keep my original?
Some videos are already efficiently compressed, so re-encoding would only cost quality. Lower the quality, resolution or frame rate for a real saving.
How long does compressing take, and is there a size limit?
Short phone clips usually take seconds; long 4K videos and AV1 take much longer. There is no fixed limit, but the result is held in memory until you download it, so on phones very long 4K videos may run out of memory.