Compress Video Online — Free & Private

Most video compressors insist on uploading your gigabytes of footage over your home internet first, which is usually where enthusiasm dies. OpenConvertVideo shrinks clips the moment you select them, right inside your browser. No account, no size limit, and your footage never leaves your device.

Drop a file here, or click to choose

Converts right here — nothing uploads

Need trim, resize, or quality controls? Open the full converter →
  • No upload wait
  • Nothing leaves your device
  • Free, no account
  • No artificial size limits

How much smaller will it get?

The result depends heavily on how your source file was originally created. Modern video codecs rely on inter-frame compression — storing only the pixel changes between frames rather than full static pictures. Because videos recorded on iPhone or Android cameras already compress real-world motion efficiently, you can expect a 30–60% reduction using the Balanced preset. Screen recordings, by contrast, contain vast static areas with zero frame-to-frame change, allowing them and footage from older cameras to often drop by 70–90%.

Reducing the resolution remains the single most effective lever for shrinking a file. Moving from 4K to 1080p eliminates three-quarters of the raw pixel count, which typically reduces file size by 70–80% before any encoding quality settings are applied.

Quality presets

  • High — minimal compression, closest to the original quality. Best for archiving or further editing.
  • Balanced — the recommended setting. Cuts file size by 50–70% with quality loss that is barely noticeable at normal viewing sizes.
  • Small — maximum compression for sending over email or slow connections. Some visible quality loss, especially in fast-motion scenes.

Compress even further with H.265

By default, compressed video is output as H.264 MP4 for maximum compatibility. If the recipient has a modern device — any Apple device, recent Android, or Windows 10/11 with the free HEVC Video Extension — switching the output codec to H.265 (HEVC) reduces file size by roughly half at the same visual quality.

A video that compresses to 200 MB in H.264 will often be around 100 MB in H.265. Select H.265 in the codec settings before converting.

Resize to reduce size further

The Resize control lets you scale the video to 1080p, 720p, or 480p before compressing. Aspect ratio is locked automatically. Combining a resolution reduction with the Balanced quality preset produces the best file size / quality tradeoff.

How it works

Compression runs entirely locally on your machine — we simply provide the code, and your own device does the actual work of compressing your file. For common formats like MP4 and MOV encoding to H.264, the system can call upon your browser's built-in encoder, which is usually hardware-accelerated; less common combinations fall back to a WebAssembly build of ffmpeg. Either way, zero bytes are transmitted to a remote server — the entire process occurs on your hardware, with no file size limit and no upload wait. Your video stays 100% private, exactly as it should.

Frequently asked questions

How much can I compress a video?
Typically 40–90% depending on the source. Screen recordings and older camera footage compress the most; iPhone and Android video is already compressed efficiently, so the gains are smaller. Switching to H.265 output cuts the size by roughly half again on top of that.
Will my video look worse after compression?
The Balanced preset produces quality loss that's barely noticeable at normal viewing sizes. For archiving or further editing, use the High preset instead — it trades a smaller size reduction for a result closer to the original, at the cost of a bigger file.
What's the difference between H.264 and H.265 output?
H.265 (HEVC) is the more modern codec — it reaches the same visual quality at roughly half the file size of H.264. The trade-off is compatibility: older Windows PCs need a free extension to play H.265 MP4 files. Use H.264 when compatibility matters most, H.265 when file size does.
Does the compressed video have a watermark?
No. The output is your video, untouched — no watermark, no logo, and no signup to remove anything. Free tools that stamp a watermark on your footage are selling its removal; this one is supported by ads on the site instead, so the file you download is simply yours.
Is there a file size limit?
No. Because nothing is uploaded, there's no server-imposed limit — the practical ceiling is your own device's available memory, which handles even large 4K files without much trouble, and there's no upload wait or queue to sit through either, no matter how big the file is.
What formats can I compress?
Any video your browser can decode — MP4, MOV, MKV, AVI, WebM, and more. Output can be MP4 (H.264 or H.265), WebM (VP9), MKV, or MOV. Common H.264 conversions from MP4 or MOV can use your browser's built-in encoder, which is usually hardware-accelerated.

Also on OpenConvertVideo