Free Video Compressor

Worked example

A 90-second 1080p phone clip of about 250 MB needs to fit in a WhatsApp chat. With "Target size" and the "WhatsApp (16 MB)" preset, the tool aims for 15 MB, which leaves roughly 1.2 Mbit/s for the picture after 128 kbps of audio. That is enough for a clean 720p image, so the page scales the video down to about 720p on its own. The output is an H.264 MP4 close to 15 MB, and the real size may differ by a few percent.

Which settings to use, and the limits

• Use Target size when a site has a limit. The presets are "Discord (10 MB)", "Discord Nitro Basic (50 MB)", "Email (25 MB)" and "WhatsApp (16 MB)". Each aims a little under the limit, because the bitrate is a single-pass estimate. The email preset aims for 18 MB since attachments grow by about a third when sent. You can also type your own size in megabytes.
• Use Quality mode for the best picture per megabyte. The slider maps to an H.264 quality value from 38 (smallest) to 18 (best). The default of 65 is a balanced setting. Lowering the resolution saves more than lowering quality, and "Max 30 fps" can cut a 60 fps screen or phone recording by about a third.
• Trim before compressing. Turn on "Trim before compressing" and only the part between Start and End is encoded. A shorter clip gets more quality from the same target size, and it finishes sooner.
• Pick MP4 unless you need WebM. MP4 (H.264) plays on iPhones, WhatsApp and PowerPoint, and is usually smaller. WebM here uses the VP8 codec, which is larger at the same quality and slower to encode.
• Expect long jobs on long videos. Encoding runs on your processor, so long 1080p clips can take many minutes, and the page warns you before a long job. Keep the tab open and in front. "Remove audio" makes a silent video and saves roughly 128 kbps.

Common problems and how to fix them

The result is not smaller than the original.

The video was already well compressed. Pick a lower resolution, move the slider towards "Smaller file", or use Target size.

Compression fails with a memory error.

The file is too big for this device's memory. Trim it, choose 720p or 480p, or use a computer. The page warns about large files first: on a phone, above about 150 MB, and the hard limit is about 400 MB.

It says the conversion failed or the file could not be read.

The file may be incomplete, still downloading, or in a format the in-browser encoder cannot read. Try the original file again, or switch the output format between MP4 and WebM.

Target size is greyed out or says it needs the duration.

The tool could not read this file's length, so it cannot calculate a bitrate. Use Quality mode instead.

Target size warns that the picture will be blurry.

The target is very small for the video's length, so there are too few kilobits per second. Trim the clip to the length the page suggests, remove the audio, or choose a bigger size.

How it compares

Quality mode and Target size solve different problems. Quality mode keeps the same visual quality and lets the file size fall where it will, which is right when you only want a smaller file. Target size fixes the file size and lets the quality fall where it will, which is right when a service has an upload limit. Compressing in the browser avoids an upload, but it is slower than a server for long videos.