Video Compressor
Lower CRF, scale resolution, or cap bitrate to hit your target size. All processing happens locally in your browser; files never leave your device.
$Drag in a video file, or click to select
Video is processed only in your browser memory
Video is read into browser memory — nothing is uploaded
CRF, resolution, encoding preset and bitrate cap
FFmpeg WASM transcodes and exports locally
Compress Video Online
Local · No uploadsShrink video file sizes by adjusting CRF (the quality-versus-size tradeoff), output resolution, and encoding preset, with an optional max bitrate. Perfect for fitting uploads under platform limits, freeing up storage, or sending large videos over email or chat. Compression happens locally — your files never leave your device.
How to Reduce Video File Size
- 1
Upload your video file
- 2
Set the CRF: higher values mean smaller files and lower quality
- 3
Optionally adjust the output resolution and max bitrate
- 4
Click Compress, then download the smaller video
Common Uses
- Get files under a platform's size limit for upload
- Free up storage space by shrinking large videos
- Make videos small enough to send over email or chat
Things to Keep in Mind
- Compression is lossy — aggressive settings visibly reduce quality
- Different encoders vary in compression efficiency
- Very large files take a long time and are limited by browser memory
How to Choose a Video Compressor
- vs. desktop tools like HandBrake or Format Factory: nothing to install — open your browser and go
- vs. upload-based tools: your files never leave your device
- Adjustable CRF / resolution / bitrate for precise size-versus-quality control
How Video Compression Works
- CRF (Constant Rate Factor) is the rate-control mode in x264/x265: lower values mean better quality and larger files. 23 is the "visually near-lossless" default, 18 reaches visually lossless, and 28 shrinks files noticeably. It keeps quality consistent frame to frame instead of targeting a fixed file size.
- The alternative is target-bitrate mode (ABR/2-pass): fix the bitrate first and get a predictable file size, at the cost of quality dips on complex scenes. That's the idea behind this tool's "max bitrate" cap — for when you must hit a specific size.
- Resolution and encoding preset are the other two levers: halving the resolution leaves only 1/4 the pixels, and slower presets (slow / veryslow) let the encoder search harder for compression, delivering better quality at the same size. Combining all three is how you reach the best size-to-quality ratio.
- This site runs x264 encoding via FFmpeg WASM in your browser — the exact same encoder as command-line FFmpeg, just running locally on your device with zero uploads.
Video Compression FAQ
Which CRF should I use?
CRF 23 is close to the original quality; 28 shrinks files noticeably; 32 is smallest but visibly degraded. Try a few values between 23 and 28 to find your sweet spot.
How much quality is lost?
It depends on your CRF and resolution settings. A low CRF at the original resolution loses very little; the harder you compress, the more visible it gets. Start with a mild compression and check the result.
Which output format is used?
MP4 (H.264) — the most compatible option, playable on virtually every device and platform.
How do I compress a video to a specific size?
Combine the "max bitrate" cap with trial and error: set a target bitrate and adjust until the output is close to your goal.
My video is too big to send — what should I do?
Raise the CRF or reduce the resolution here to shrink it dramatically, then send it by email or chat.