Compress Video to an Exact File Size

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Common ways to use this tool

Compress video to an exact file size

Set a hard MB ceiling instead of guessing with a quality slider. The muxed result is measured before it is offered as complete.

Compress video to 20 MB

Start from the 20 MB preset, then let Auto balance audio bitrate, frame rate, and resolution for the selected duration.

Compress video for email

Use the 20 MB or 25 MB email presets, or enter the exact attachment limit required by your provider.

Trim and compress without uploading

Remove an unneeded beginning or ending before encoding so the retained footage receives a larger bitrate budget.

PrivateTools

About Exact-size Video Compressor

Exact-size Video Compressor starts from a byte ceiling, not an arbitrary quality percentage. It subtracts a safety margin, MP4 muxing reserve, and optional audio budget from the selected limit, then assigns the remaining bits to H.264 video for the chosen trim range. The downloaded result is only marked successful after its actual file size has been checked.

Supported formats

  • Input: MP4, MOV, AVI, MKV, WebM, and other formats supported by the shared trimy conversion pipeline
  • Output: web-compatible MP4 with H.264 video and AAC audio when audio is retained
  • Size presets: 5, 10, 20, 25, 50, and 100 MB, plus a custom limit

Why it is different

  • Calculates video and audio bitrate directly from duration and the selected byte limit.
  • Fast mode leaves a larger safety margin; Max quality uses more of the available ceiling.
  • Max quality samples five scenes locally to estimate motion and fine detail before Auto chooses output geometry.
  • Auto can reduce high frame rates and step through practical output resolutions when the budget is too small.
  • Checks the completed muxed file and performs at most one proportional correction pass if the first result is too large.
  • Never labels an oversized result as a successful exact-size export.

Privacy and local processing

Metadata analysis, trimming, video decoding, encoding, muxing, correction, and file-size verification run in the browser. The source video is not uploaded to PrivateTools.

FAQ

Will the downloaded file be under my selected limit?

A result is offered as successful only after the completed MP4 is measured at or below the selected byte limit. If the first encode is too large, the tool can make one lower-bitrate correction. If that still misses, it reports the problem instead of returning an oversized success.

Why is the planned size below the exact limit?

Video bitrate control is not perfectly deterministic, and the MP4 container also needs bytes for indexes and metadata. A small safety margin makes the hard ceiling reliable.

Should I trim or lower the resolution?

Trim first when possible: fewer seconds means more bits for every retained second. Auto resolution is useful when the requested duration and limit cannot support the source pixel count cleanly.

What is the difference between Fast and Max quality?

Fast leaves a little more headroom to reduce the chance of a correction pass. Max quality samples five scenes for motion and detail, targets more of the available budget, and uses the quality-oriented encode settings.