How to Resize Images for Email Attachments: Size Limits and Best Practices
Learn the optimal image sizes for email attachments. Avoid bounced emails and slow delivery by properly sizing your images.
Email with image attachment showing size optimization
Why Email Image Size Matters
Sending large image attachments via email can cause several problems: emails may be rejected by mail servers, take too long to send or receive, fill up inbox storage quotas, and frustrate recipients with slow downloads. Understanding email size limits and optimizing your images accordingly ensures your messages are delivered successfully.
Email Size Limits by Provider
Gmail: 25MB total attachment limit per email
Outlook/Hotmail: 20MB per email (34MB for Microsoft 365)
Yahoo Mail: 25MB per email
iCloud Mail: 20MB per email (use Mail Drop for larger files)
Corporate Servers: Often 10-15MB (check with IT department)
Remember, these limits apply to the total email size, including all attachments combined. Base64 encoding increases attachment size by about 33%, so a 15MB file becomes about 20MB in the email.
Recommended Image Sizes for Email
For Viewing on Screen:
- Full-size photos: 1920 x 1080 pixels (Full HD) - typically 200-500KB as JPEG
- Standard sharing: 1280 x 720 pixels - typically 100-200KB as JPEG
- Quick previews: 800 x 600 pixels - typically 50-100KB as JPEG
For Printing:
- 4x6 print at 300 DPI: 1200 x 1800 pixels
- 8x10 print at 300 DPI: 2400 x 3000 pixels
How to Reduce Image Size
1. Resize Dimensions: Most photos from modern phones are 12+ megapixels (4000x3000 pixels). For email viewing, 1920x1080 is usually sufficient.
2. Compress Quality: JPEG quality of 80-85% maintains good visual quality while significantly reducing file size.
3. Choose the Right Format: Use JPEG for photos (smaller files), PNG only when transparency is needed.
4. Remove Metadata: EXIF data (camera settings, GPS) can add 50KB+ to each image.
Best Practices
- Consider the recipient's needs - do they need print quality or screen viewing?
- Resize images before attaching, not after
- Use ZIP compression for multiple images
- For large batches, use cloud sharing (Google Drive, Dropbox) and send a link
- Test email delivery with a message to yourself first
Using ImageResizer.site for Email Images
Our free tool makes it easy to resize images for email. Simply upload your image, set width to 1920 pixels (or smaller), choose JPEG format, and download. The compressed image will be perfect for email while maintaining good quality.