You hit Send in iMessage, the spinning indicator appears, you wait, and then nothing happens. Or the message ships with no attachment. Or — most commonly — you see an error like "Attachment too large" and the message refuses to go.

This post explains exactly why iMessage rejects attachments, what the actual size limits are (they're not what Apple's documentation says), and three concrete ways to fix it.

What iMessage actually limits

Apple's official limit per attachment over iMessage is 100 MB. In practice, the limits that bite are stricter and depend on the path your message takes:

| Path | Effective max | What happens at the limit | |---|---|---| | iMessage to iMessage (both Apple devices, iOS 17+) | ~100 MB | Sent natively | | iMessage falls back to email (recipient is non-Apple) | ~25 MB (Gmail) or ~35 MB (Outlook) | Silently truncated or rejected | | iMessage Mail Drop fallback | up to 5 GB | Recipient downloads via iCloud link | | SMS/MMS fallback (carrier-dependent) | 300 KB – 1.6 MB | Forcibly compressed beyond recognition |

The frustrating bit: iMessage doesn't tell you which path it's about to take until it sends. If your recipient just upgraded to an iPhone but you don't know it, you'll get different behavior than yesterday.

Why your specific video is "too big"

Most "iMessage attachment too big" errors are videos. Here's the typical math:

30-second 4K screen recording at 60 fps with H.264: ~250 MB
1-minute iPhone 15 Pro video at 1080p 60 fps: ~150 MB
A QuickTime screen recording of "just five minutes of testing": easily 500 MB+

iMessage will see these and choose Mail Drop (cloud link) or refuse. Neither is what you want for casual sharing.

Three ways to fix it

Option 1: QuickVid Compress (the one-click answer)

Full disclosure: QuickVid Compress is one of the apps I make. The flow:

1. Drop the video onto QuickVid 2. Pick "Recommended" mode (or "Tiny" if you need under 25 MB) 3. Save the output 4. Drag the output into iMessage

Default: H.264 at a sensible bitrate. Typically takes a 250 MB 30-second screen recording down to ~30 MB with no visible quality loss. Pro tier adds HEVC encoding (~30% smaller again) and a custom "Tiny" mode that targets specific size caps.

Time start to finish: under a minute.

Option 2: Use macOS's built-in QuickTime export

Free, no app needed:

1. Open the video in QuickTime Player 2. File → Export As → 720p (or 480p for very large originals) 3. Save and drag the new file into iMessage

QuickTime's export uses H.264 by default. The downside: only three resolution presets (4K, 1080p, 720p, 480p) and no bitrate control, so you might end up with a file that's smaller but bigger than needed for iMessage.

Option 3: ffmpeg from Terminal

If you live in the command line:

```bash

Brew install if you don't have it

Q: What's the maximum video size for iMessage?

Apple's official limit is around 100 MB per attachment over iMessage between two Apple devices. If iMessage falls back to email (when the recipient isn't on iMessage), the effective limit drops to ~25 MB for Gmail or ~35 MB for Outlook. Mail Drop can carry up to 5 GB but recipients receive a download link rather than the video itself.

Q: Why does iMessage say my video is too large?

Most likely your video is over 100 MB and iMessage can't send it natively. A typical 30second 4K screen recording at 60 fps is ~250 MB; a 1minute iPhone video at 1080p is ~150 MB. Compressing with H.264 at 1080p typically brings these down 6080% with no visible quality loss.

Q: How do I compress a video for iMessage on Mac?

Three good options: (1) QuickVid Compress — drop, pick mode, done in under a minute. (2) QuickTime Player → File → Export As → 720p. (3) ffmpeg from Terminal with c:v libx264 crf 24. QuickVid is fastest if you do this regularly; QuickTime is fine for oneoffs.

Q: Can I send a video over 100 MB in iMessage?

iMessage will automatically offer to send it via Mail Drop, which generates an iCloud link (good for 30 days). Mail Drop works for up to 5 GB. The downside: recipients need a working internet connection at the time they open the message. If you can compress to under 100 MB, native sending is more reliable.

Q: What's the best video format for iMessage?

H.264 in an MP4 container is the safest universal choice — works on every Apple device, every fallback path, and most email gateways. HEVC (H.265) is 30% smaller at the same quality but can hit transcoding issues with nonApple recipients. Default to H.264; switch to HEVC only when you know all recipients use modern Apple hardware.

brew install ffmpeg

Compress to iMessage-friendly H.264 at ~CRF 24

ffmpeg -i input.mov -c:v libx264 -crf 24 -preset medium -c:a aac -b:a 128k output.mp4

Target ~25 MB specifically (for Gmail-fallback safety)

bitrate ≈ (target_size_MB × 8000 ÷ duration_seconds) kbps

ffmpeg -i input.mov -c:v libx264 -b:v 1500k -c:a aac -b:a 96k -movflags +faststart output.mp4 ```

Scriptable, reproducible, free. Steep learning curve for first-timers.

What I'd specifically avoid

Web-based "free" video compressors (e.g., the ones that pop up first on Google). They upload your video to their server. If you're compressing a screen recording with internal Slack, customer data, or personal moments, the cost is real. Run macOS's App Privacy Report during a compression test — outbound network activity is the smoking gun.

Mac App Store apps that ask for a subscription to compress. Compression is a finite, repeatable task. There's nothing recurring to pay for. One-time Pro purchases are fine; recurring subscriptions for this specific job are not.

Sending via Mail Drop and hoping recipient downloads. Mail Drop generates an iCloud link that expires after 30 days. Recipients on slow networks or restrictive workplaces often can't access it. If you can compress to under 100 MB, do that instead.

Quick rules of thumb

For different recipients, here's what to target:

| Recipient | Aim for | Resolution | Codec | |---|---|---|---| | Apple-only friend | ≤ 90 MB | original | HEVC (smaller) or H.264 (compatible) | | Mixed-platform group | ≤ 90 MB | 1080p | H.264 | | Will probably fall back to email | ≤ 20 MB | 720p or 1080p | H.264 | | Family member with old iPhone | ≤ 50 MB | 720p | H.264 | | Posting on a tight-limit platform (Discord free, Slack) | ≤ 24 MB | 1080p (or 720p) | H.264 |

The conservative default that handles everything: H.264 at 1080p, target 25 MB output.

Why H.264 over HEVC

HEVC produces 30% smaller files at the same quality. So why default H.264 for sharing? Three reasons:

1. iMessage transcodes some HEVC paths to H.264 anyway when forwarding to non-Apple recipients. Sending HEVC, getting transcoded H.264, ends up bigger. 2. Corporate email gateways sometimes fail on HEVC. H.264 is the safest LCD. 3. Older devices (iPhone < 7, MacBook < 2015) decode HEVC in software, leading to laggy playback. Audience matters.

If you know everyone's on current Apple hardware, HEVC is fine.

Closing

If you compress videos for iMessage more than once a month, a dedicated tool pays for itself in saved time and reliability. QuickVid Compress is what I built for this — drop, pick mode, ship. Free tier handles the basics; Pro adds HEVC, batch, and the "Tiny" mode for hitting specific size targets.

If you're a once-a-quarter user, QuickTime export is good enough. If you live in the command line, ffmpeg is the right answer.

Frequently asked questions

What's the maximum video size for iMessage?

Apple's official limit is around 100 MB per attachment over iMessage between two Apple devices. If iMessage falls back to email (when the recipient isn't on iMessage), the effective limit drops to ~25 MB for Gmail or ~35 MB for Outlook. Mail Drop can carry up to 5 GB but recipients receive a download link rather than the video itself.

Why does iMessage say my video is too large?

Most likely your video is over 100 MB and iMessage can't send it natively. A typical 30-second 4K screen recording at 60 fps is ~250 MB; a 1-minute iPhone video at 1080p is ~150 MB. Compressing with H.264 at 1080p typically brings these down 60-80% with no visible quality loss.

How do I compress a video for iMessage on Mac?

Three good options: (1) QuickVid Compress — drop, pick mode, done in under a minute. (2) QuickTime Player → File → Export As → 720p. (3) ffmpeg from Terminal with -c:v libx264 -crf 24. QuickVid is fastest if you do this regularly; QuickTime is fine for one-offs.

Can I send a video over 100 MB in iMessage?

iMessage will automatically offer to send it via Mail Drop, which generates an iCloud link (good for 30 days). Mail Drop works for up to 5 GB. The downside: recipients need a working internet connection at the time they open the message. If you can compress to under 100 MB, native sending is more reliable.

What's the best video format for iMessage?

H.264 in an MP4 container is the safest universal choice — works on every Apple device, every fallback path, and most email gateways. HEVC (H.265) is 30% smaller at the same quality but can hit transcoding issues with non-Apple recipients. Default to H.264; switch to HEVC only when you know all recipients use modern Apple hardware.