Email Signature Image and Logo Size: The Specs That Display Everywhere

For Gmail, Google recommends a signature image 300 to 400 pixels wide and 70 to 100 pixels high, with a hard maximum of 1,000 by 100 pixels. Save it as a PNG, keep the file small (vendor guidance ranges from about 15 KB to 100 KB), and host it at a public URL. Get those four things right and most “missing logo” tickets never happen.

What size should an email signature logo be?

Start with Google’s own numbers, because Gmail is where your signature is built. Google’s Gmail Help says: “We recommend a signature image that’s 70–100 pixels high by 300–400 pixels wide,” and “The maximum size for email signature images is 100 pixels high by 1000 pixels wide” (Gmail Help).

Signature vendors mostly go smaller for the logo itself, because it sits alongside a name, title and phone number:

Source	Logo or image guidance	File size
Google (Gmail Help)	300 to 400 px wide, 70 to 100 px high; max 1,000 × 100 px	Not stated
HubSpot	Logos “150×50 pixels maximum”	“under 15-20KB”
Exclaimer (for Gmail)	“around 80 pixels in height and up to 200 pixels wide”	“under 15kb”
WiseStamp	Horizontal logos “150-200px wide and 70-100px high”	“under 100KB” to “under 120KB”

Sources: Gmail Help, HubSpot, Exclaimer, WiseStamp. Vendor figures are their own guidance, not standards.

A sensible default for a company rollout: a horizontal logo displayed at about 150 to 200 pixels wide and no more than 100 pixels high, with the whole signature block kept within Google’s 400-pixel recommended width.

Step 1: Pick the right format

Use PNG for logos. HubSpot notes “PNG format works best for email signature images due to transparency support,” and transparency matters for dark mode (more on that below). Use JPG for photos. GIF is the only option if you need animation, though animated signatures are rarely worth the distraction.

Skip SVG. Support is patchy: Gmail rasterizes linked SVGs into PNG, older Outlook for Windows doesn’t display them, and inline SVG code is stripped out entirely (Can I email). Patronum’s own help center is direct about it: “it is not possible to embed SVG images into your email signatures” (Patronum Help).

Step 2: Export at the size you want displayed

Here the advice splits. WiseStamp recommends exporting at double size (“A logo meant to display at 150px should be saved at 300px”) so it looks crisp on high-resolution screens. Exclaimer says the opposite: design and upload at display size.

Our take: don’t upload a large image and shrink it with HTML. As Patronum’s guidance puts it, “some email clients will ignore the code and display the image in the original size” (Patronum Help). That’s how a neat 180-pixel logo turns into a banner that fills the whole screen in someone’s inbox. If you do export at 2x for sharpness, test it in Outlook before rolling it out.

Step 3: Keep the file small

Gmail signatures have a 10,000-character limit, and Google notes “Your image also counts toward the character limit” (Gmail Help). Smaller files also load faster on mobile. Aim for the low end of the vendor range, ideally under 20 KB for a logo.

Step 4: Host it somewhere every recipient can reach

This is where most broken logos come from. Gmail gives you three ways to add an image: a web address, Google Drive, or an upload from your device. If you use Drive, “the image sharing settings must be set to public,” and on work accounts an admin may need to allow that. Delete the file later and “the image won’t show in the signature” (Gmail Help).

Also watch out for images on internal servers. Gmail serves images through Google’s proxy, and Google warns that “links to images that are dependent on internal IPs and sometimes cookies are broken” (Google Workspace Admin Help). If a logo only works on the office network, recipients won’t see it.

For step-by-step hosting options, see our guide on storing email signature images in Google Drive.

Step 5: Check dark mode and Outlook

Two last checks before rollout.

• Dark mode. A logo on a solid white box can look odd, or vanish, when a recipient’s email client inverts colors. Litmus recommends “transparent backgrounds wherever possible,” and adding a subtle outline to dark text on transparent PNGs (Litmus).
• Outlook. Classic Outlook “is configured by default to block automatic picture downloads from the Internet” (Microsoft Support). Some recipients will see a placeholder until they click. Make sure your signature still reads well as text, and give the logo sensible alt text.

Where people get this wrong

• Uploading the original 2,000-pixel brand file and resizing it in the editor.
• Hosting logos on an intranet or behind a login.
• Using SVG because it looked perfect in the design tool.
• Letting every employee add their own logo, so ten versions circulate at ten different sizes.

That last one is an admin problem, not a design problem. With Patronum’s email signature management, you set the logo once in a signature policy, target it by organizational unit, group or directory attribute, and Patronum syncs it to every user’s Gmail through the Gmail API. If someone edits their signature, the policy puts it back on the next sync.

FAQ

What is the best size for an email signature logo? Around 150 to 200 pixels wide and up to 100 pixels high works for most layouts. Keep the full signature within Google’s recommended 300 to 400 pixels wide.

What’s the maximum image size Gmail allows in a signature? Google says the maximum is 100 pixels high by 1,000 pixels wide, and the image counts toward the 10,000-character signature limit.

Why is my logo showing huge in some emails? Usually because a large image was scaled down with HTML, and the recipient’s email client ignored the scaling. Export the image close to its display size.

Can I use an SVG logo in my signature? It’s not recommended. Gmail converts linked SVGs to PNG, older Outlook versions don’t show them, and inline SVG is removed. Use a PNG instead.

Get every logo right, once

If your logo still isn’t appearing, work through our Gmail signature logo troubleshooting guide. And if you’d rather set the correct logo for the whole company in one place, see how Patronum manages Gmail signatures.

Sources

• Gmail Help, signature images and troubleshooting: https://support.google.com/mail/answer/11468381?hl=en
• Gmail Help, create a Gmail signature: https://support.google.com/mail/answer/8395?hl=en
• Google Workspace Admin Help, image URL proxy: https://knowledge.workspace.google.com/admin/gmail/advanced/set-up-an-image-url-proxy-allowlist
• HubSpot, email signature image guide: https://www.hubspot.com/email-signature-generator/email-signature-image
• Exclaimer, email signature size: https://exclaimer.com/email-signature-handbook/using-the-right-email-signature-size/
• WiseStamp, email signature image size: https://www.wisestamp.com/guides/what-is-the-correct-email-signature-image-size/
• Can I email, SVG images: https://www.caniemail.com/features/image-svg/
• Litmus, dark mode guide: https://www.litmus.com/blog/the-ultimate-guide-to-dark-mode-for-email-marketers
• Microsoft Support, picture downloads in classic Outlook: https://support.microsoft.com/en-us/office/block-or-unblock-automatic-picture-downloads-in-classic-outlook-email-messages-15e08854-6808-49b1-9a0a-50b81f2d617a
• Patronum Help Center, embedded images not showing: https://help.patronum.io/en/article/embedded-images-not-showing-in-email-signature-1kn49u7/
• Patronum Help Center, manage multiple Gmail signatures: https://help.patronum.io/en/article/manage-multiple-gmail-signatures-8bua8j/