Manatee

How to shrink a video for a job application or course upload

· 6 min read

A portal that says “max 50 MB” or “max 100 MB” will take a clear 720p or 1080p video if you size it properly. A file’s size is its length times its bitrate, so a two-minute introduction under 50 MB has about 3 Mbps to spend, which is plenty for a person talking to a camera. Read the whole upload page for the real rules, aim about 10 percent under the limit, name that number in a shrink tool, and check the result is an MP4 that plays to the end.

Find the real limit

The number in bold is rarely the only rule. Read the instructions and the text around the upload box for these:

  • Per file or per submission. “100 MB” on a course assignment may cover everything you attach, the video and the slides PDF together.
  • A length limit. “No longer than two minutes” matters more than any size. Some portals refuse a longer file outright; others accept it and leave the reviewer to stop watching.
  • Accepted formats. Usually listed as extensions: MP4, MOV, sometimes M4V or WebM. If the list says only MP4, an iPhone’s .mov file can be refused even when it is small enough.
  • How a megabyte is counted. Finder counts 1 MB as 1,000,000 bytes; some systems count 1,048,576, and the page rarely says which. A margin covers both, so aim for 45 MB under a 50 MB limit and 90 MB under a 100 MB one.
  • Whether a link is allowed. Some applications accept a link to a video hosted elsewhere. If yours does, the file size stops mattering.

Also note the deadline. A 90 MB upload over slow home internet can take several minutes, and a portal that times out halfway tends to show a vague error rather than a clear message. Upload early.

The size math in plain words

Size equals length times bitrate. One megabit per second (1 Mbps) of video for one minute comes to about 7.5 MB. So divide your target in MB by the length in minutes, then divide by 7.5, and you have roughly the bitrate you can afford.

Here is approximately what that gives for the two common limits, with the margin built in:

Length Aim for 45 MB (50 MB limit) Aim for 90 MB (100 MB limit)
1 minute 6 Mbps: 1080p, easily 12 Mbps: more than you need
2 minutes 3 Mbps: 1080p talking head, fine 6 Mbps: 1080p, easily
3 minutes 2 Mbps: 720p, comfortably 4 Mbps: 1080p talking head, fine
5 minutes 1.2 Mbps: 720p talking head or slides 2.4 Mbps: 720p, comfortably
10 minutes 0.6 Mbps: tight, so trim or ask about a link 1.2 Mbps: 720p talking head or slides

These figures include the sound, which needs only about 0.1 Mbps for a clear voice. A person sitting still against a plain wall is about the easiest thing there is to compress; a walking shot, a busy background or a screen full of scrolling needs more.

The table also tells you when to stop trying. A ten-minute presentation under 50 MB will look soft whatever tool you use. The honest fixes are a shorter video, or a link if the instructions permit one. The full arithmetic, with a two-pass Terminal route for people who want to set every number, is in how to shrink a video to a specific file size.

Record so it survives compression

Reviewers forgive a slightly soft picture. They do not forgive a voice they cannot follow. Most of the quality is decided before you compress anything.

  • Record at 1080p or 720p, not 4K. On an iPhone, the setting is in Settings > Camera > Record Video. Starting at 4K only means more to throw away later.
  • Keep the camera still. Use a tripod or a stack of books. Shake makes every pixel change in every frame, and changing pixels are what cost bits. A plain wall behind you is cheaper than a bookshelf, a window with moving trees or a ceiling fan.
  • Light your face. A dim room adds grainy noise, and the encoder spends bits on the noise instead of on you. Sit facing a window.
  • Get the microphone close. A phone two meters away records the room; a wired earbud microphone records you. Skip background music, which competes with your voice.
  • Make slide text big. If you are presenting slides, fine print is the first thing to blur at a low bitrate. Large type survives almost anything.
  • Trim the edges. Open the video in QuickTime Player, choose Edit > Trim, and cut the reach for the record button at the start and the walk to stop it at the end.

Name the target in Manatee

QuickTime’s 1080p and 720p presets cannot aim at a number, so you export, check, and try again. Manatee works from the number instead.

  1. Trim first in QuickTime, as above. Manatee is not an editor and will not cut anything.
  2. Open Manatee, choose Shrink, and type your target: 45 for a 50 MB limit, 90 for a 100 MB one.
  3. Drop the video onto the window or the menu bar icon, or right-click it in Finder and choose Services > Fix with Manatee.
  4. Manatee finds the quality that fits and writes a new file next to the original. The original is never changed.
  5. Watch the new copy full screen and listen with headphones: your face, any slide text, and whether your words stay clear.

If it looks too soft, the target is too low for the length. Shorten the video and shrink the original again, rather than shrinking the already-shrunk copy. Everything runs on your Mac with no upload and no account, which is a sensible property for a video of your face, your voice and possibly your home. Every feature is free for the first 24 hours, then $9 once.

Check the portal will accept it

  1. Look at the extension. If you cannot see it, turn on Finder > Settings > Advanced > Show all filename extensions. If the file ends in .mov and the portal lists only MP4, convert it; renaming it is not the same thing. How to convert MOV to MP4 on a Mac explains why, and Manatee’s Convert mode lists MP4 among its targets.
  2. Think about who opens it. iPhones record HEVC in their default High Efficiency setting, which some portals and older Windows laptops cannot play. If you are unsure, an H.264 MP4 is the version least likely to be refused. Switching the iPhone to Most Compatible in Settings > Camera > Formats before you record gives you H.264 from the start; for a file you already have, see how to convert HEVC to H.264.
  3. Check the size. Select the file and press Command-I. The Size line gives the exact byte count first, with the rounded size on disk in parentheses after it.
  4. Remove the location. A video recorded on a phone at home can carry the coordinates of your home. Manatee’s Clean mode strips GPS and camera details, writing a cleaned copy beside the original.
  5. Name it properly. Firstname-Lastname-Introduction.mp4, not IMG_4412.MOV. The same habits apply as for a resume, covered in how to get a PDF under 2 MB for a job application.
  6. Play it to the very end before you upload, and if the portal offers a preview afterward, watch the first few seconds there too.

Questions

Should I upload in 4K so it looks its best?

No. Under the same size limit, 4K spreads the same bitrate across four times the pixels of 1080p, so it looks worse, not better, and many platforms re-encode uploads for playback anyway. A clean 1080p file looks as good on a reviewer’s laptop.

The portal says my file is invalid, but it is under the limit. Why?

Usually the format rather than the size: a .mov where MP4 is required, HEVC video the portal cannot read, or a file that was renamed instead of converted. Convert it to MP4 and try again.

Can I zip the video to get it under the limit?

It will barely shrink, because video is already compressed, and many portals will not accept a zip in a video field anyway. Shrink the video itself.

Is it better to lower the resolution or the quality?

Let the bitrate decide. If the table above gives you 2 Mbps or more, keep 1080p or 720p and let the quality adjust. Below about 1 Mbps, a smaller picture that stays clean beats a large one full of smeared blocks: in QuickTime Player, choose File > Export As > 720p or 480p, then shrink that copy. Trimming the length beats both.