How to Compress a Video on Mac

The fastest way to compress a video on Mac is to open it in QuickTime Player, choose File > Export As, and pick a size below the original. Here's what each option actually produces, where the finer controls live, and which lever gives you the biggest saving.

Compress a video on Mac with QuickTime Player's Export As

File > Export As gives you a ladder of sizes. 1080p exports a QuickTime movie using H.264 or HEVC up to 1920 by 1080. 720p uses H.264 up to 1280 by 720. 480p uses H.264 up to 640 by 480. There's also Audio Only, which produces an Apple MPEG 4 file with an AAC track — worth remembering for the times the picture was never the point.

Each step down that ladder removes a large share of the pixels, and pixels are what a video file is mostly made of. This is the single most effective thing you can do, and it's one menu.

At 1080p, a Format pop-up also appears with two choices: Smaller File Size, which exports in HEVC, and Greater Compatibility, which exports in H.264. HEVC is the newer codec and reaches a given visual quality in fewer bits, so it's the one to pick unless the file has to play on something old.

When you need a specific number instead of a preset

Presets are fine until something imposes a hard limit and you're 4 MB over it. That's what iMovie's export dialog is for.

Share > Export File offers a Resolution pop-up, where lower resolutions produce smaller files that upload more quickly, and a Quality pop-up that includes Medium and Low. Choosing Custom in Quality replaces the presets with a slider for the target bit rate, which is the control you actually want when you're aiming at a number. There's also a Compress pop-up governing how long iMovie takes over the conversion, and an Allow export segmentation checkbox that speeds up exports of longer projects on capable hardware.

Bit rate is where quality is really lost, so move it in small steps and watch a busy section. Fast motion and fine detail show compression damage long before a talking head does.

The efficient choice, made once and not offered again

Montaj exports in HEVC as an .mp4, at 1080 by 1920. There's no size ladder to navigate and no format pop-up to get wrong, because the efficient option is the only one it produces. The same choice you'd make manually in QuickTime Player, made once.

It runs entirely on your device, so a long clip isn't waiting on an upload before it can be processed, and there's no watermark and no export limit on the way out. If you need a specific bit rate or a legacy-friendly H.264 file, compress a video on Mac with the built-in tools above. They give you controls Montaj deliberately doesn't.