You attach a video, press send, and the message bounces back with "attachment too large". Every email service and messaging app caps how much data you can send, and the caps differ. This article explains the typical limits, why they exist and what to do when a file will not go through. Figures below are typical values at the time of writing; services change them, so check the current number in the app's help pages.
Why limits exist
Attachments cost money to store and deliver. An email with a 20 MB attachment is copied to the sender's outbox, the recipient's inbox, backups and scanning systems. Limits keep services affordable and responsive, and protect recipients with small mailboxes or slow connections.
Typical limits
- Email. Many providers allow about 20 to 25 MB per message. Because attachments are encoded for email, a file takes about a third more space than its original size, so a 20 MB file may not fit under a "25 MB" limit. Larger files are often offered through a cloud-drive link instead.
- Messaging apps. Photos and videos are usually recompressed to save bandwidth. Video clips sent as ordinary media may be limited to a small size (often around 16 MB in some apps), while sending as a "document" allows much larger files, up to hundreds of megabytes or even a couple of gigabytes depending on the service.
- Social media. Platforms accept large uploads but recompress and cap duration, resolution or aspect ratio.
- Online forms and portals. Often 100 KB to a few megabytes per file.
- Free file-transfer sites. Commonly allow a few gigabytes via a download link that expires.
How to get under the limit
Photos
Resize to 1600 pixels on the long side and save as JPG at around 80 percent quality. Most photos shrink from several megabytes to a few hundred kilobytes without visible difference on a screen. Use the File Size Reducer with its live preview to find the right level.
Videos
Trim unnecessary seconds, reduce the resolution to 720p and choose H.264 MP4. See the video compression guide for the settings. For WhatsApp, our WhatsApp and email guide shows the quick route.
Audio
Voice recordings do not need music-grade quality. Convert to M4A or MP3 at 64 kbps mono and a one-hour meeting becomes about 30 MB or less. The Audio Converter handles it.
Documents and PDFs
Reduce the resolution of embedded images, scan in grey instead of colour and avoid embedding unnecessary fonts. Split a very large PDF into two parts if needed, or merge several small ones with the PDF Merger to avoid ten separate attachments.
When compression is not enough
- Use a cloud-drive link. Upload the file to your drive, set sharing to "anyone with the link" and paste the link. The recipient downloads it without limits.
- Send as a document in messaging apps to avoid recompression.
- Split into parts with an archive tool that supports multi-part ZIP.
- Use a transfer service for one-off large transfers.
Quality surprises
When you send a photo as an ordinary image in a messaging app, it is typically recompressed and may lose detail, which matters for documents and prints. If you need exact quality, send as a document or file. Conversely, large originals are unnecessary for casual viewing, so a resized copy is kinder to the recipient's data plan and storage.
A quick decision table
| Situation | What to do |
|---|---|
| Photo for a chat | Send normally; it will be compressed for you |
| Photo that must stay sharp | Send as a document/file |
| Video over a messaging limit | Trim and compress, or send as a document or via a link |
| Email attachment over 20 MB | Compress, or share a cloud link |
| Form with a KB limit | Reduce dimensions, then compress and verify the size |
Be kind to recipients
People read mail on phones with limited data. A 15 MB attachment is a cost to them. Sending a smaller version with an offer to share the original on request is considerate and usually works better.
Keep the originals, send what the situation needs, and use compression deliberately. Most "too large" problems disappear with a resize, a sensible format and a few minutes of work.
Platform-by-platform workflow
- Email on a computer. Compress the attachment, check the size is well under the limit, and prefer a cloud link for anything above about 15 MB.
- Email on a phone. Phone mail apps often offer to resize pictures when attaching; choose a medium size for casual sharing.
- Messaging apps. Photos are recompressed unless sent as files; for videos choose "send as document" or share a link for quality or size beyond the media limit.
- Portals. Use the exact format and size asked for, and name files simply.
Mobile data and storage
Big attachments also cost recipients data and storage. On mobile plans, a 30 MB video is a real cost. If the content does not need to be sharp, reducing resolution and trimming is both polite and faster. Remember that messaging apps keep downloaded media on the phone; sending smaller files saves your contacts storage as well.