How to Compress a Video Under 100MB for Online Submission

Start with these choices

Use this order to reduce repeat attempts

Set the submission requirements and target before opening a compressor, then treat playback review as part of the workflow.

• Copy the portal's maximum size, accepted format, duration, resolution, aspect-ratio, and file-name requirements into a checklist.
• Keep the original and set the submission copy's target 5–10% below the stated limit.
• Start with MP4 and a resolution close to the source; if the result is too large, step down from 1080p to 720p before crushing quality.
• Play the downloaded file from start to finish, then verify audio, captions, file size, extension, and name before uploading.

Check more than the file-size limit

Compressing immediately after seeing ‘100MB maximum’ can still leave you with the wrong format, an overlong video, or an unsupported aspect ratio. Read the full submission specification first.

When a portal asks for MP4 but does not name codecs, H.264 video with AAC audio is a broadly compatible choice across browsers and PCs. A specification supplied by the recipient overrides this general recommendation.

• Maximum file size
• Accepted container and codecs
• Maximum duration
• Resolution and aspect ratio
• File-name and deadline rules

For a 100MB limit, aim around 90–95MB

100MB is 100,000,000 bytes; 100MiB is 104,857,600 bytes. Interfaces may label either MB, so compare actual bytes with the recipient’s rule.

A 90–95MB target is a working margin, not an official standard. Follow the recipient’s exact calculation rule when one is supplied.

Longer videos have fewer bits available per second

If two videos must fit the same 100MB limit, the longer one has less data available for every second. A one-minute clip and a ten-minute presentation cannot retain the same visual quality at the same final size.

A mostly static presentation usually compresses more efficiently than sports, games, foliage, water, grain, or rapid camera movement. Complex motion can look blocky sooner at the same target size.

720p can look better than an over-compressed 1080p result

Keeping every 1080p pixel under a strict size limit can leave too little information per pixel. Reducing the frame to 720p may produce a cleaner result because the available data is spread across fewer pixels.

For screen recordings, diagrams, or lectures with small text, test a representative section before reducing resolution. The resolution number alone does not tell you whether the content remains readable.

A target size is an estimate, not a promise

Video encoders can allocate data differently from scene to scene. Motion, noise, cuts, and texture make two files with the same length and resolution finish at different sizes.

If the first result is slightly too large, lower the target or resolution one step instead of immediately selecting the lowest quality. If it is far below the limit and important details look soft, you may have room to raise the target or resolution.

Inspect the output, not only the source

A working source does not guarantee a working submission copy. Open the downloaded MP4 separately and check that the beginning and ending are present, audio is synchronized, captions are readable, and orientation is correct.

Finally confirm the actual file size, extension, duration, and required file name. Keep the source and submission copy clearly separated to avoid uploading the wrong version.

• Play the beginning, middle, and end
• Check audio and synchronization
• Read the smallest caption or slide text
• Confirm orientation and aspect ratio
• Verify size, extension, duration, and file name

Inspect a test export containing presentation text

We compressed a roughly ten-second fictitious business presentation with a 1MiB target and a maximum height of 720p. The 1920×1080 source, 32,099,518 bytes, became a 1280×720 result of 774,987 bytes. This short sample demonstrates settings and text checks; its source is about 32.1MB.

The source already fits a 100MB cap, so that cap alone would not require compression. For a smaller limit or a longer presentation, first inspect a passage containing important text. The 1MiB target means entering 1 in the tool’s target field: 1,048,576 bytes.

Play the actual compressed result below. First read 120 completed items, 24 in review and the 2026-11-30 deadline, then check the smaller footer note. A clear title does not establish that small numbers and conditions remain readable.

• Download file · MP4Download the 720p compressed MP4
• View source image · PNGFull-frame source image for comparison

Readable text is not necessarily as sharp as the source

The checked date and smaller footer remained readable in the result. At a matching enlarged size, however, character edges and thin lines look softer than the source. A smaller file does not mean unchanged image quality.

These crops show the footer at the same eight-second position. The 720p frame was resized to the source dimensions before cropping the same region. In addition to enlargement, inspect the whole video at your recipient’s viewing size. Distinguish a small on-page display from text breaking down in the saved file.

This is one short presentation with limited motion, not a promise of the same size or readability for rapid cuts, more movement or smaller text. Check sound and synchronization separately when your own footage has audio.

• Read related articleSee the separate comparison of different resolutions