Compress Video to Size

What Compress Video to Size helps you do

Hit a specific upload limit instead of guessing a quality preset. Enter a target in megabytes, and the tool works backwards from the clip length to a bitrate that can fit, then encodes the video toward that size. It is built for the practical ceilings people run into: a chat attachment, a messaging document, an email limit or a form that rejects anything larger.

The target calculation and the encode both run in your browser. The source file is not uploaded and no copy is stored by Haivix.

How it works

The target size is converted into a total bitrate by dividing the available bits by the duration, then subtracting an allowance for audio and container overhead. The encoder receives that video bitrate and the resolution you selected. Because encoders do not hit a bitrate exactly, and because variable-bitrate content uses more bits in complex scenes, the finished file can land a little above or below the number you asked for.

How to use Compress Video to Size

1. Load the video and check its duration and current size.
2. Enter the target size in megabytes, for example 10 or 25.
3. Lower the resolution if the target is very small relative to the length.
4. Start the encode and keep the tab open.
5. Compare the result with the target and the original.
6. Adjust the target slightly and run again if the file overshoots.

When to use it

• Fit a clip under a chat or messaging upload limit.
• Prepare an attachment for an email provider with a fixed cap.
• Meet a form or portal limit without opening a desktop editor.
• Shrink a recording for a slower connection while keeping a known budget.
• Test whether a target size is realistic before promising a file.

When not to use it

• Do not use it when quality matters more than an exact number; use a quality preset instead.
• Avoid an aggressive target on a long clip, because the bitrate may become too low to read text.
• Do not assume a platform limit is permanent; services change their caps without notice.

Example

A four-minute screen recording is 96 MB and must fit a 10 MB chat upload. The target-size mode calculates a bitrate for 10 MB, and the tool caps the long edge at 720p to give the encoder more room per pixel. The result lands at about 9.8 MB, with interface text still readable on a phone.

What you can do with Compress Video to Size

• Set any target size in megabytes.
• Cap the resolution alongside the target.
• Choose MP4 for compatibility or WebM for a smaller result.
• Keep the audio track within the size budget.
• See the original and output sizes side by side.
• Run the encode locally with no upload.

Example workflow

Trim before targeting a size. A two-minute clip can afford roughly twice the bitrate of a four-minute clip at the same limit, which usually makes the difference between readable and mushy text.

If the result misses the target, adjust one variable at a time. Changing the resolution gives a larger effect than nudging the target by a megabyte, and it is easier to predict.

What to know before you start

• The target is an estimate, not a guarantee; overhead and encoder behaviour cause small misses.
• Very small targets on long videos can produce unreadable text.
• The encode happens in memory, so very large sources may fail on low-memory devices.
• Audio quality is reduced to make room for video when the budget is tight.
• Only one target is produced per run.

Common mistakes

• Setting a 10 MB target for a 40-minute recording and expecting sharp text.
• Forgetting that audio also consumes part of the budget.
• Uploading the result without checking the platform's current limit.
• Deleting the original before confirming the compressed file plays on the target device.

Troubleshooting

If the result is a little over the limit, lower the target by 5–10 percent rather than re-encoding repeatedly. The overhead varies with the container and the number of tracks.

If the picture is unreadable, reduce the duration or the resolution. A lower-resolution file at the same byte budget spends more bits per pixel and often looks better than a sharp-looking source at a very low bitrate.

If the encode fails, the source may be too large for the browser's memory. Split it with the trimmer and compress the parts separately.

If the platform rejects the file despite the right size, check the container and codec rather than the byte count. Some services accept only MP4 with H.264 and AAC regardless of the file size.

Related standards and documentation

• H.264/AVC is the codec used for the most compatible MP4 output.
• ISO/IEC 14496-12 describes the MP4 container overhead included in the estimate.