Email signature size and dimensions
There's no official standard, but email's practical limits make the numbers fairly settled. Here they are, and why logos need files twice their on-screen size.
| Element | Display size | Export file at (2×) | Format & weight |
|---|---|---|---|
| Whole signature | up to 600px wide; ~320px for phone-friendly | — | — |
| Logo | 100–200px wide | 200–400px wide | PNG (transparent) or JPG; < 50 KB |
| Headshot | 80–100px square | 160–200px square | JPG; < 40 KB |
| Banner | 450–600 × 90–150px | 900–1200 × 180–300px | JPG or PNG; < 100 KB |
| Social icons (if images) | 16–24px | 32–48px | PNG; a few KB each |
| Text | 12–14px body, name 16–20px | — | web-safe font |
Display size is what you set in the HTML width attribute (the generator's logo slider). Export size is the actual file.
Why a logo file should be twice its display width
Most phones and many laptops draw every on-screen pixel with two (or three) physical pixels in each direction. A 150px-wide logo on such a screen covers 300 device pixels. If the file is only 150px wide, it gets stretched and goes soft. Try it:
Why 600px wide?
Email templates have been built around a 600px content column for years because it fits reading panes in desktop clients with the folder list open. A signature wider than the message looks odd and forces horizontal scrolling in some clients. On phones, clients shrink wide content to fit, so a 600px signature becomes small text; narrower is better if most of your mail is read on mobile.
Outlook and high-DPI Windows screens
Classic Outlook for Windows scales emails at display settings like 125% or 150%. Images without a width attribute can appear at their raw file size, so a 400px file meant to show at 200px suddenly fills the signature. The generator writes both the attribute and an inline width on every image to prevent this.
Hosting your images
Signature images must load from a public https:// address. Good options: your own website's media folder, your CMS or website builder's media library, or your company's CDN. Avoid Google Drive and Dropbox share links, which point to a viewer page rather than the image file, and anything behind a login. Once uploaded, open the image address in a private browser window: if you see just the image, it will work in a signature.
Ready to try your numbers? The generator has a logo-width slider and warns you when an image won't travel with the signature.
Questions people ask
What is the best size for an email signature?
Keep the whole signature under 600px wide, the classic email body width, and aim for roughly 100–150px tall for the main block (without banner or disclaimer). Most readers see it on a phone, where anything wider than about 320–350px starts to scale down.
What size should a logo be in an email signature?
Display it at 100–200px wide, and export the file at twice that width (200–400px) so it stays sharp on Retina and other high-density screens. Set the display size with the HTML width attribute.
What size should an email signature banner be?
A common size is 450–600px wide by 90–150px tall on screen, exported at 2× (e.g. 900 × 200px). Keep the file under about 100 KB.
What size should a headshot be?
Around 80–100px square on screen, exported at 160–200px square. Crop it square yourself; a circle crop made with CSS won't show in classic Outlook.
How big should the image files be?
Aim for under 50 KB per image and under about 150 KB for the whole signature. Every image loads with every email you send, including on slow mobile connections.