Compress Video to Size

How target-size compression works

The size of a video is, very nearly, its bitrate multiplied by its duration. Turn that around and you can solve for the bitrate that produces a chosen size: bitrate ≈ target size ÷ duration. This tool does exactly that — it takes your target (say 10 MB), subtracts a fixed allowance for the audio track, reserves a little headroom for container overhead, and encodes the video at the bitrate that is left. A longer video has to share that budget across more seconds, so it ends up at a lower bitrate; a shorter clip can keep more detail at the same size.

Why two-pass hits the number

A single-pass encode has to guess how to spend bitrate as it goes, so the final size can drift above or below the target. Two-pass fixes that. The first pass analyses the whole video without writing a usable file, recording how complex each section is. The second pass uses that map to distribute the bitrate budget precisely — more to fast, detailed scenes and less to simple ones — so the finished file lands at-or-under the size you asked for. It costs about twice the encoding time, which is why there are limits on length here.

Compressing a video for email

Most email providers cap attachments: Gmail allows about 25 MB, Outlook around 20 MB, and many corporate mail servers are tighter. The For email (8 MB) preset aims comfortably under those limits so the message actually sends and the recipient can download it without a cloud link. If you specifically need to fit Gmail, the 25 MB preset is the one to pick.

When to lower the resolution

If you are targeting a very small size for a long clip, the maths can demand a bitrate so low that the video would look blocky at full resolution. The fix is to remove pixels before encoding: stepping down to 720p or 480p means each frame needs fewer bits, so the same small target buys a much cleaner-looking result. The tool never changes the aspect ratio — it only scales the long edge down — so your video keeps its shape.

Target size vs the Video Compressor

Use Compress Video to Size when you have a hard number to hit — an email limit, an upload cap, a 10 MB ceiling. If you don't need an exact number, you can also just pick a generous target here and let the encoder keep as much quality as that size allows. Both output a universal MP4; they simply answer two different questions.

The limits

Without an account you can compress one file up to 100 MB and 5 minutes; a free account raises that to 200 MB and 10 minutes. The length cap keeps each two-pass encode fast, because the whole job runs while you wait. The output is always an MP4 with H.264 video and AAC audio.

1. Upload the clip you need to get under a hard size limit.

2. Pick 8MB for email, 10MB, 25MB, or type any custom target.

3. Two-pass encoding solves the bitrate and hits the number; see the arithmetic behind it in the Video File Size Calculator.