How to compress a video to email it on Mac (2026 guide)

You try to attach a video to an email and get the dreaded bounce: “attachment size exceeds the allowed limit.” A 90-second clip from your phone can easily be 150–300 MB, and email providers cap attachments far below that. You don’t need a different email account — you need a smaller file.

This guide shows how to compress a video on your Mac to fit an email, using the tools already on your machine and the one-click option when you’d rather not think about it. Everything here runs locally — your video never gets uploaded to a compression website.

Know the number you’re aiming for

Compression is much easier when you have a target. The common email attachment limits in 2026:

• Gmail: 25 MB per message.
• Outlook / Microsoft 365: 20 MB by default.
• iCloud Mail (Apple Mail): 20 MB — but with Mail Drop, larger files are uploaded to iCloud and sent as a link, up to 5 GB (more on that below).
• Yahoo Mail: 25 MB.

Chat apps are tighter still — WhatsApp caps shared video around 16 MB, and Discord’s free tier limits uploads too — so if that’s the real destination, aim smaller.

A safe universal target is under 20 MB. Hit that and the file goes almost anywhere.

Why videos are so big (and what actually shrinks them)

Three things drive a video’s file size:

1. Resolution — 4K has four times the pixels of 1080p. Dropping from 4K or 1080p to 720p is the single biggest, easiest win for something that’s only going to be watched in an email.
2. Bitrate — how much data is spent per second. Phones record at very high bitrates; you can cut this substantially before anyone notices.
3. Codec — H.265 (HEVC) packs the same quality into roughly half the size of the older H.264. Re-encoding to H.265 is a free size cut on any modern Mac.

Compressing means turning one or more of these knobs. The tools below just make it easier or harder to do so precisely.

Method 1: QuickTime Player (free, no target control)

QuickTime can export at a lower resolution, which is often enough:

1. Open the video in QuickTime Player.
2. File → Export As.
3. Choose a smaller resolution — 720p or 480p.
4. Save, then check the new file’s size in Finder.

Fast and built-in. The catch: QuickTime gives you a handful of resolution presets and no way to target a specific size — you export, check, and try a lower preset if it’s still too big. Fine for a quick one-off, frustrating when you need to land just under 20 MB.

Method 2: ffmpeg (free, total control)

With ffmpeg installed (brew install ffmpeg), you can compress precisely.

Re-encode to efficient H.265 with a quality target (CRF — lower is higher quality; 28 is a good starting point for email):

ffmpeg -i input.mov -c:v libx265 -crf 28 -c:a aac -b:a 128k output.mp4

Also drop it to 720p for a much smaller file:

ffmpeg -i input.mov -vf "scale=-2:720" -c:v libx265 -crf 28 -c:a aac -b:a 128k output.mp4

If you need to hit an exact size, use two-pass encoding with a calculated bitrate. For a 20 MB target on a 60-second clip, that’s roughly a 2,500 kbps total bitrate:

ffmpeg -i input.mov -c:v libx264 -b:v 2300k -pass 1 -an -f mp4 /dev/null && \
ffmpeg -i input.mov -c:v libx264 -b:v 2300k -pass 2 -c:a aac -b:a 128k output.mp4

ffmpeg is the most capable option and completely free. It’s also the least forgiving: you’re doing bitrate arithmetic, and getting an exact size means understanding two-pass encoding. Great if you enjoy it; a lot of ceremony if you just want to send a clip.

Method 3: Zumkor (pick a size, click convert)

The reason Zumkor exists is that “make this fit in an email” shouldn’t require CRF math. Compression is one of its core jobs:

1. Open Zumkor and drag in your video.
2. Pick a size preset for where it’s headed — Zumkor ships targets for Gmail (25 MB), Outlook (20 MB), WhatsApp (16 MB), Discord (10 MB), and Notion (5 MB).
3. Click Convert.

For those presets Zumkor re-encodes efficiently and then iteratively nudges the bitrate and resolution until the file actually lands under the cap — so you never export, check, and try again. It all happens on your Mac, nothing uploaded, so a personal video never touches a compression website. Drop in several videos at once and it compresses the whole batch in one pass, converting the container to MP4 at the same time if the source is an MKV or MOV.

It’s a one-time $19.99 purchase, no subscription. The honest trade-off: QuickTime is free and already installed if you only ever do this once and don’t care about the exact size. Zumkor is for people who send files regularly and want to pick a size, drag a batch, and be done — the same way they’d convert HEIC photos to JPG or turn an MKV into an MP4 without a separate tool for each.

The alternative: don’t compress at all (Mail Drop)

If you’re sending from Apple Mail with an iCloud account and quality matters more than delivering a true attachment, Mail Drop sidesteps the whole problem. Attach the full-size video; when it exceeds 20 MB, Mail offers to send it via Mail Drop, which uploads it to iCloud and inserts a download link. The recipient clicks to download the original, uncompressed.

Two caveats: the file goes to iCloud (not fully local), and the recipient gets a link rather than an inline attachment. For a pristine copy it’s ideal. For a video that just needs to arrive in the message, compressing to fit is simpler.

A note on privacy

Videos, like photos, can carry metadata — including location. And unlike a quick photo, a video is a large, personal file you may not want sitting on a stranger’s server “just to make it smaller.” That’s the case against free web compressors, and the reason every method above keeps the file on your Mac. If you’re also sharing photos, the same principle applies — see converting HEIC to JPG on Mac, which can strip location data in the same pass.

Bottom line

• Aim under 20 MB and your file goes almost anywhere.
• Quick and free: QuickTime → Export As → 720p, then check the size.
• Exact size, free: ffmpeg with CRF, or two-pass for a precise target.
• Pick a size and forget the math: Zumkor, offline, batch, no upload.
• Need pristine quality over a true attachment: Apple Mail’s Mail Drop.

The wrong move is uploading a personal video to a random “compress video online” site. Your Mac can do it locally in less time than the upload would take.