the clip is fine. the upload made it look terrible.

the three things that decide how your video lands

• the frame. a landscape clip in a vertical feed is either cropped by the platform, wherever it feels like, or dropped into bars. deciding that yourself is the biggest difference on this page.
• the resolution. above 1080p on the vertical feeds nothing is gained: it is scaled down on arrival, and scaling then re-encoding is two losses instead of one.
• the bitrate. too low and you see it immediately; too high and the platform's own compressor works harder against you and you see that instead.

the three-minute length and the 1080p ceiling are YouTube's own numbers: create a YouTube Short

and the format rule that catches people out — TikTok states mp4 or webm, 720x1280 or higher, up to 30 minutes, under 10 gb: making a post on TikTok

the frame and the format are two different jobs, and only one of them is on this page — the other is here: a file converter for Mac

the built-in way to compress video on a Mac

Encode Selected Video Files, in the Finder right-click menu

macOS does have one. select a clip in Finder, Control-click it, and look under Quick Actions for Encode Selected Video Files. it takes a whole selection, leaves the originals alone, and costs nothing. underneath it is a command-line tool called avconvert handed one of thirteen named settings, and that is where its ceiling comes from.

1. select the clips in Finder and Control-click them.
2. Quick Actions → Encode Selected Video Files.
3. pick a setting — 480p, 720p, 1080p or 4K, in H.264 or HEVC — and a destination folder.
4. press Continue. the copies land beside the originals with the setting in the name.

on a six-second 2160×3840 test clip, the 1080p setting gave back a 1080×1920 file and took it from 18.0 mb to 6.1 mb. the box it fits into does not care about orientation — the long side goes on the long side — so a vertical clip comes back vertical. that is the case this menu is good at, and it is a common one: shot vertically on a phone, too heavy to send.

what it will not do

• it will not change the frame. hand it a 3840×2160 landscape clip and the 1080p setting returns 1920×1080 — still 16:9, still wrong for a vertical feed. there is no crop, no 9:16, no 4:5 anywhere in the menu.
• it will not let you choose a bitrate. on that test clip the 1080p setting decided on roughly 8 mbit/s by itself. avconvert has no bitrate switch at all, so neither does the menu.
• it will not write mp4. twelve of the thirteen settings produce a QuickTime .mov and the thirteenth is audio-only — which is the whole problem for TikTok, whose upload wants mp4 or webm.
• the resolution ladder is 480p, 720p, 1080p and 4K, and nothing between. «1080 across but softer» is not an option the menu has.
• the two settings that sound like compression — LowQuality and MediumQuality — live only in the command-line tool, and on the same clip they returned 124×224 and 320×568. iPod-era sizes, not reel sizes.

the full list of settings, if you want to read it before running anything: man avconvert

the same Finder menu does images too, and there the built-in answer goes much further: convert heic to jpg

iMovie, when the frame has to change

once the shape is wrong, you are in an editor. iMovie is free and already installed, and it will get you there.

1. make a project and set it to a vertical aspect — iMovie will do 9:16 for a project created as one.
2. put the clip on the timeline and reframe it by hand: crop to fill, and check that the thing you care about is still in the middle.
3. Share → Export File, pick 1080p and a quality, and export.
4. check the file's size, and if the bitrate was wrong for what you wanted, do it again with a different quality.

so what should you actually do

if the clip is already the right shape and only too heavy, stop here: Control-click it, Encode Selected Video Files, 1080p. nothing on this page beats that, and you do not need an app for it.

the simple case ends the moment the shape is wrong, the destination is more than one, or the file has to come in under a stated size. from there the free route stops asking you to press a button and starts asking you to know things — which of thirteen settings, that none is vertical, that the bitrate is not yours to pick, that what comes out is a .mov. the cost is paid in knowledge and repeats, not money.

and the free route does not start at all if macOS will not open the file — a screen recording in mkv is its own job first: open an mkv file on Mac

how hop compresses video for reels and shorts

hop's converter has one button per destination — reels, feed, TikTok, shorts or YouTube. pressing it writes the frame, the resolution and the squeeze together, from what the platform itself recommends, and shows the bitrate it means beside the dial. you are not guessing at three settings that have to agree with each other; you are naming where the clip is going. it runs on your Mac, which for unreleased footage is the argument against the free online resizers.

the same «get it under the limit» problem, with a different kind of file: compress a pdf on Mac

when your reels still look worse than they did on your Mac

• you are watching the platform's preview, not the finished upload. the first minutes after posting often show a lower-quality pass while the real one is still being made.
• the footage is dark, or has a gradient sky, or heavy grain. these are what video compression is worst at, and no preset rescues them — more light when filming does.
• there is fine text on screen. text survives resolution and dies to bitrate; if it has to be readable, it has to be big, not sharp.
• you uploaded over a phone connection and the app re-compressed to save data. several of these apps have a setting for that, and it is usually not on the setting you assumed.
• the clip was already exported once by an editor and once by a converter. every pass costs something — export from your edit at high quality and let the destination pass be the second one, not the fourth.

if the problem is the container rather than the frame — a .mov nothing will accept, which is also what the Finder menu hands you: convert mov to mp4

and if what you actually needed was the text that was on screen: copy text from a video

frequently asked questions

can i compress a video on a Mac without installing anything?

yes. Control-click the file in Finder and choose Quick Actions → Encode Selected Video Files. it re-encodes at 480p, 720p, 1080p or 4K and leaves the originals alone. what it cannot do is change the shape of the picture or write mp4.

what size should a vertical video be?

9:16, 1080 pixels across. going higher is thrown away on arrival, and the extra pixels cost you an additional scale-down before the platform's own compression.

how long can a YouTube short be?

up to three minutes. the old one-minute limit is gone, and YouTube also states 1080p as the maximum resolution a Short keeps — so there is nothing to gain from uploading more.

why does my video look blurry after uploading?

it was re-encoded, and usually scaled or cropped as well. handing over a file already at the right frame and resolution means only the re-encode happens, and that one is hard to notice.

can i stop the platform from compressing my video?

no. every one of them re-encodes on upload. the whole craft here is giving that pass as little work as possible.

one clip for three platforms — do i need three exports?

three files, yes, because the frames differ. what you do not need is three edits: export once at quality, then convert that master into each frame.

the tool behind this

done with convert and compress

other things people do

• a folder of heic, and something that wants jpgfile converter
• mov and mp4 are often the same filefile converter
• QuickTime will not open it. the video is fine.file converter