Email Header Size
The email header is the banner image at the top of a newsletter. Design it 600 px wide — that is the safe content width every major email client renders without side-scrolling — and export at 1200 px (2×) so it stays sharp on retina screens.
| Placement | Pixels | Ratio | |
|---|---|---|---|
| Content width Safe width for Gmail, Outlook, Apple Mail |
600 px | — | |
| Common header Typical banner block above the fold |
600×200 | 3:1 | |
| Retina export Export at 2× and set width=600 in HTML |
1200 px wide | — | |
| File limit Keep images light so the email loads fast |
≤1 MB | — |
Design to 600 px wide
600 px is the de-facto safe content width for HTML email — Gmail, Outlook and Apple Mail all render it without horizontal scrolling. A header banner is commonly 600×200 (3:1), but any height works as long as the width is 600.
Export at 2× for retina
Export the image at double resolution — 1200 px wide — then set width="600" in the HTML. This keeps the header crisp on high-DPI screens without changing the layout width.
Always set width and alt text
Set explicit width and height so the layout holds before images load, and add alt text — many clients block images by default, so the alt is what recipients see first.
FAQ
What size should an email header image be in 2026?
600 px wide is the safe content width for all major clients; a common header is 600×200 (3:1). Export at 1200 px (2×) for retina.
Why is 600 px the standard email width?
It is the widest layout Gmail, Outlook and Apple Mail all render without horizontal scrolling, so it became the de-facto standard.
How do I make an email header sharp on retina?
Export the image at 1200 px wide (2×) and set width="600" in the HTML so it displays at 600 px but renders crisply on high-DPI screens.