Flyers · Glossary
Email signature banner size: width, height and weight
An email signature banner is usually about 600 pixels wide and 80 to 100 pixels tall, with guides suggesting up to 650 wide, and it should stay under about 40 KB. Make it at twice the size and display it smaller so it is sharp on high density screens. In Gmail, the whole signature counts against a 10,000 character limit.
A signature banner travels on every email someone sends, often hundreds a week, so it has to be small in two ways: short enough not to dominate the message and light enough not to bloat it.
Indunil Asanka · Co-founder
3 min read · Published
| Measure | Value | Source |
|---|---|---|
| Banner width | 600 px, full width signature | Bulk Signature, October 2026 |
| Banner height | 80 to 100 px; 600 x 100 maximum | Bulk Signature |
| Banner around 650 px wide | About 100 px tall | Right Inbox |
| Banner weight | Under 40 KB; animated GIF under 45 KB | Right Inbox, Bulk Signature |
| Logo | Up to about 200 px wide, under 30 KB | Bulk Signature |
| Resolution | Make images at 2x, then scale down | Bulk Signature |
| Gmail signature limit | 10,000 characters, images included | Gmail Help |
A band, not a billboard
A signature banner sits below the sender's name and contact details and carries one message: an upcoming event, a new service, an award. At about 600 by 80 to 100 pixels it is a shallow band that fits beneath the text without pushing the conversation off screen. Guides from Bulk Signature and Right Inbox agree on that range. Anything taller starts to look like advertising stapled to every reply, which recipients notice quickly in a long thread.
Why weight matters more here
A signature repeats on every message and every reply, so a heavy banner multiplies across a thread. Right Inbox suggests keeping a banner under 40 KB and an animated GIF under 45 KB, and Bulk Signature puts the whole signature's images under about 50 KB. Some clients show embedded images as attachments, which clutters the message, so hosted images linked by URL are usually the cleaner option when the signature tool allows it.
Sharpness and dark mode
Bulk Signature recommends creating signature images at twice their display size, so a 600 by 100 banner is exported at 1200 by 200 and shown at 600 by 100. That keeps edges crisp on high density screens. Dark mode is the other trap: a banner with a transparent background and dark text can become unreadable when an inbox inverts colours, so give the banner its own solid background.
Common mistakes
Using a banner as tall as an email header. Saving a photo banner as a large PNG. Embedding text that matters, such as a phone number, only in the image, where it cannot be copied or tapped. Leaving a campaign banner on months after the event. And pasting a banner into Gmail at full size, which counts against the 10,000 character limit when the image is embedded.
Making a signature banner
The flyer editor has no 600 by 100 canvas, so it does not make a signature banner directly. Its LinkedIn Post canvas at 1200 by 627 is the right width for a 2x banner, so a single band of text and logo designed across its middle can be cut to 1200 by 200 with the image cropper and shown at 600 by 100. The image compressor brings it under 40 KB, and the blank 600 by 100 PNG on this page is a 1x canvas.
Questions people ask
Should a signature banner link somewhere?
Yes. Most signature tools let the banner image carry a link, which is the point of a banner: it sends people to the event page, booking page or offer. Use a short, trackable address so clicks from signatures can be counted separately from other traffic.
Can an email signature banner be animated?
An animated GIF works in many clients, and Right Inbox suggests keeping it under 45 KB with two or three simple frames. Bulk Signature warns that animated GIFs break in Outlook desktop, where only the first frame may show, so the first frame should carry the whole message.
What size should the logo in a signature be?
Bulk Signature suggests a logo no wider than about 200 pixels and under 30 KB, made at 2x. Right Inbox suggests around 100 by 100. A logo that is too large competes with the banner and makes every reply long; keep it modest.
Why does my signature banner show as an attachment?
Some email clients treat embedded images as attachments, which adds a paperclip icon and clutter. Hosting the image online and linking it by URL avoids that in most clients. Keeping the file small also reduces the chance of it being treated as a separate attachment.
How long can a Gmail signature be?
Gmail Help says a signature can hold up to 10,000 characters and that an image counts toward that limit. If Gmail shows an error when adding a banner, resizing the image to a smaller file, or linking it rather than pasting it, usually fixes it.
Make one with flyers
The button opens the generator with this use case already described. Change the wording to match your own.
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Written and checked by the OneCraft team. Last checked .