Attachment limits of common email services
Each email service sets how large a single email can be. Usually the limit covers the message text and all attachments together.
Company and school email often has its own limit set by the administrator. If the recipient’s limit is smaller than yours, the email can be sent but won’t arrive.
| Email service | Limit | Notes |
|---|---|---|
| Gmail (personal accounts) | 25MB | Larger files are added as a Google Drive link automatically |
| Outlook.com | 25MB | For the whole email, including text and attachments |
| Yahoo! Mail (Yahoo! JAPAN) | 25MB total | Including the message text; up to 50 attachments |
| docomo mail | 10MB total | Total size of attachments |
Attachments grow by about a third when sent
Email sends files such as PDFs by converting them into text data. Because of this, the size actually sent is about a third larger than the original file (roughly 1.3–1.4 times).
A 20MB PDF, for example, can go over 25MB when sent. With a 25MB limit, keeping your attachments to about 18MB in total is safe.
Choosing a target size
If the recipient hasn’t given a size, use these as a guide:
- Sending to clients or people you don’t know: 2MB–5MB (you don’t know their limit, so smaller is safer)
- Between Gmail, Outlook.com and Yahoo! Mail: up to about 18MB in total
- Sending to docomo mail: up to about 7MB in total
If the recipient will print the file, or fine detail matters (such as drawings), consider sending a cloud storage link instead of shrinking it hard.
How text stays readable
The tool first compresses only the photos and scanned images in your PDF, keeping text and layout as they are wherever possible. Documents made in Word or Excel usually shrink enough at this stage, and text can still be selected and searched.
Only if that isn’t enough are pages turned into images to shrink further, and never below a quality where text stays readable.
If it still won’t send
- Split the PDF and send it across several emails
- Delete pages you don’t need, then compress again
- Send a share link from Google Drive or OneDrive (Gmail and Outlook.com can send large files as links)
Sending with a password
To add a password to a document you’re sending, compress it here first, then use Password-Protect PDF. Password-protected PDFs can’t be compressed by this tool.
Your file is never uploaded
Your PDF isn’t uploaded to a server; it’s compressed only on your device. Confidential documents such as quotes and contracts are never sent anywhere. The data is discarded when you close the page.