image / PRACTICAL GUIDE
Best Image Size for Email
Pick dimensions that are easy to view and a file size that leaves room for the whole message.
For a photograph sent for casual viewing, start around 1200–1600 pixels on its long edge and reduce bytes until the detail is still clear. This is an editorial starting point, not an email-provider limit. Send originals when the recipient needs to edit or print them.
THE IDEA, VISUALLY
Display size and file size are different
- Layout width
- Pixel dimensions
- Exported bytes
Distinguish viewing from delivery
A photograph sent for a quick look does not need the same dimensions as an image sent for print production. Ask whether the recipient needs to see it, edit it, or print it.
For casual viewing, a long edge around 1200–1600 pixels is a reasonable starting point. This is general guidance, not a specification from an email provider.
Budget for all attachments
Email systems often encode attachments for transport, adding roughly one third to the raw byte size before other message overhead. Multiple images share the same message budget.
Provider and organization limits vary and can change. Check both the sending service and the recipient’s rules. Leave a margin rather than trying to fill the exact limit.
For example, four images of 750,000 bytes total 3,000,000 raw bytes. Base64 represents those bytes in about 4,000,000 characters, before line breaks and message headers. This illustrates transport overhead; your provider may advertise its limit in raw attachment bytes instead.
References: RFC 2045: Base64 transport encoding; Gmail Help: current attachment rules
Send the right version
| Purpose | Starting point | What to preserve |
|---|---|---|
| Casual photo viewing | 1200–1600 px long edge | Faces and relevant detail |
| Text-heavy screenshot | Keep enough pixels for readable labels | Text at the recipient’s viewing size |
| Transparent logo | PNG at intended display size | Transparent edges |
| Print or editing | Original through an accepted transfer method | Source detail and metadata |
Keep email images understandable
Give files descriptive names and include a short explanation in the message. If inserting images into HTML email, supply meaningful alternative text in the authoring application.
Reduce a document attachment without confusing pages with photos
Frequently asked questions
Is 600 pixels the best width for every email image?
No. An image embedded in a designed email has a layout width; a photo attachment has a separate viewing purpose. Follow the email template’s dimensions for embedded graphics, and keep text readable.
Should I use WebP in email?
Only when your receiving workflow supports it. Browser WebP support does not prove support in every email client. Test with the recipient’s application or use an accepted JPG/PNG copy.