How to Compress Video for iMessage (Under 100MB)
iMessage doesn't publish a strict file size limit, but in practice videos over about 100MB get silently re-compressed to a tiny blurry version — or fail to send with 'Not Delivered'. The fix is to compress the video yourself first. AVMint does it in your browser so the original never leaves your Mac or iPhone.
Open AVMint Compress
On your Mac or iPhone, open AVMint's Compress tool in Safari. No app install — it runs on WebAssembly inside the browser tab.
Drop the video you want to iMessage
Drag and drop (or tap to select) the MOV or MP4 you want to send. AVMint reads it directly from your device.
Target around 80MB
Pick a target of 80MB to stay safely under iMessage's invisible re-compression threshold. Click Compress, then share the result directly from your device into Messages.
Tip
If you're sending from iPhone, use AVMint in mobile Safari instead of emailing the file to yourself first. That way you skip the extra iCloud round trip.
Why iMessage silently ruins big videos
Unlike email or Slack, iMessage often does not show a clear 'file too large' error. When the clip is too big, Apple's pipeline may re-encode it on the way out — sometimes to a smaller resolution, sometimes to a bitrate so low that fine detail disappears. Compressing to ~80MB yourself gives you more control and reduces the chance of an aggressive automatic downgrade.
Typical result
Illustrative values from a common 1080p H.264 source. Your actual ratio depends on source bitrate, content complexity, and target bitrate.
AVMint pre-compress vs iMessage auto-downgrade
| AVMint pre-compress | iMessage auto-downgrade | |
|---|---|---|
| Output resolution | Kept (e.g. 1080p) | Often dropped hard |
| Bitrate control | You set the target | Apple picks (aggressive) |
| Visible quality on receiver | Crisp | Blurry / pixelated |
FAQ
Why does iMessage make my video look terrible?
When a video is too large, iMessage aggressively re-encodes it to fit. Compressing the clip yourself to around 80MB gives you full control over the output quality.
Does this work on iPhone Safari?
Yes. AVMint runs in mobile Safari using WebAssembly. Performance depends on your device but works on modern iPhones.
Is there an official iMessage video size limit?
Apple does not publish a public hard limit. In practice, clips over around 100MB reliably get silently re-encoded into blurry low-bitrate versions. Pre-compressing to ~80MB is the sweet spot for arriving crisp.
Can I keep HEVC for the iMessage send?
HEVC is fine when everyone is on modern Apple hardware, but it is less predictable in green-bubble conversations or mixed-device group threads. Converting to H.264 MP4 first is the safer bet for broad playback.
Related reads
How-to
How to Compress Video for WhatsApp
Compress videos for WhatsApp chat so they send faster and survive WhatsApp's re-encoding. AVMint runs in your browser with no upload required.
How-to
iPhone Video Won't Send or Arrives Blurry? Here's the Real Fix
iPhone videos fail to send or arrive blurry because of HEVC codec issues and service size caps. Convert and compress in your browser with AVMint — no upload, no account.
Use case
Compress Video to Send on LINE — Beat the 5-Minute Auto-Cut
LINE auto-cuts videos longer than 5 minutes and re-encodes large files into a blurry mess. Trim and compress in your browser with AVMint before you send.
Sources & references
Files never leave your device
Open AVMint Compress