How to Add a Logo to Your Email Signature (Size and Format Guide)

An email signature logo is a company or personal brand image placed inside the sign-off block of your outgoing emails. Adding a logo reinforces brand recognition in every message you send, turning routine correspondence into a consistent branding opportunity that reaches every recipient's inbox.

Your logo is the most recognizable element of your brand. It appears on your website, your business cards, your presentations, and your social profiles. Yet many professionals overlook the place where it gets the most daily impressions: their email signature. The average business professional sends 40 or more emails per day. That is 40 chances to put your brand in front of clients, partners, and prospects without spending a cent on advertising.

This guide covers everything you need to get your logo into your email signature correctly, from file dimensions and formats to hosting strategies and client-specific instructions.

Why Add a Logo to Your Email Signature?

Brand Recognition at Scale

Every email you send is a brand touchpoint. A logo in your signature creates visual consistency across all external communications. Over time, recipients associate your logo with the quality of your work, making your emails instantly recognizable in crowded inboxes.

According to a Lucidpress study, consistent brand presentation across all platforms increases revenue by up to 23%. Email signatures are one of the simplest channels to control, yet one of the most commonly neglected (Lucidpress, 2021).

Professionalism and Trust

A logo signals legitimacy. Recipients are more likely to trust emails from senders who present a polished, branded signature than those with plain text sign-offs. For sales teams, consultants, and client-facing roles, this trust translates directly into higher response rates and stronger first impressions.

Emails that include branded elements such as a company logo and consistent color scheme see up to 18% higher engagement rates compared to unbranded messages, based on email marketing research by Campaign Monitor.

Free Marketing in Every Message

Unlike paid advertising, your email signature costs nothing to deploy. A logo paired with a link to your website, a campaign banner, or a scheduling page turns every email into a passive marketing channel. For teams of 50 or more people, this adds up to thousands of branded impressions per week.

Optimal Logo Dimensions for Email Signatures

Getting the size right is the single most important technical decision. A logo that is too large dominates the signature and looks unprofessional. One that is too small becomes unreadable.

Recommended Sizes

Specification	Recommended Value
Display width	150-300px
Display height	30-80px
Source file width	300-600px (2x for retina)
Source file height	60-160px (2x for retina)
Maximum file size	50KB
Aspect ratio	Maintain original ratio

The ideal email signature logo dimensions are 150 to 300 pixels wide and 30 to 80 pixels tall for display, with a source file at double those dimensions (300 to 600 pixels wide) so the logo renders crisply on retina and high-DPI screens. Keep the file size under 50KB to avoid deliverability issues.

Horizontal vs. Stacked Logos

Most companies have multiple logo formats. Choose the right one for the signature context:

Horizontal/wordmark logos work best in email signatures because they fit naturally alongside contact details. Aim for 200-300px wide, 30-50px tall.
Stacked logos (icon above text) work if your horizontal version is unavailable, but they take up more vertical space. Keep these 100-150px wide, 60-80px tall.
Icon-only logos (logomark without text) can work at 40-60px square but sacrifice name recognition. Only use these if your icon is widely known.

Retina Display Considerations

Modern screens on MacBooks, iPhones, and many Windows laptops use high-DPI (retina) displays that render images at 2x pixel density. If your logo source file matches the display size exactly, it will look blurry on these screens.

To ensure your email signature logo looks sharp on retina displays, export the source image at exactly double the intended display size. For example, if you display the logo at 200px wide, your source file should be 400px wide. Then set the HTML width attribute to 200 to force the browser or email client to scale it down, using the extra pixels for crispness.

<!-- Display at 200px, source is 400px for retina clarity -->
<img src="https://yourcompany.com/logo.png"
     alt="Acme Corporation"
     width="200"
     height="40"
     style="display: block;" />

Always set both width and height attributes explicitly. This prevents email clients from rendering the image at its full source size, which would make a 400px file appear twice as large as intended.

File Formats: PNG vs. JPG vs. SVG

The format you choose affects quality, file size, and compatibility across email clients.

Format Comparison

Format	Transparency	File Size	Email Support	Best For
PNG	Yes	Medium	Universal	Logos with transparency
JPG	No	Small	Universal	Photos, complex images
SVG	Yes	Tiny	Very poor	NOT recommended for email
GIF	Yes (1-bit)	Small	Universal	Simple logos, limited colors
WebP	Yes	Small	Partial	NOT recommended for email

PNG: The Best Choice for Most Logos

PNG is the recommended format for email signature logos because it supports transparency, preserves sharp edges on text and line art, and is universally supported across all email clients including Outlook, Gmail, and Apple Mail.

Use PNG when:

Your logo has a transparent background
Your logo contains text, sharp lines, or geometric shapes
You need crisp rendering without compression artifacts
You want the logo to sit cleanly on any background color

Optimize your PNG using tools like TinyPNG or Squoosh to reduce file size without visible quality loss. A well-optimized PNG logo can be under 20KB.

JPG: When File Size Is Critical

JPG works for logos that sit on a solid background and do not need transparency. It produces smaller files than PNG but introduces compression artifacts, especially around sharp edges and text. If your logo is primarily type-based (a wordmark), JPG compression will make the edges look fuzzy.

Use JPG only when:

Your logo has a solid, non-transparent background
The logo is photographic or gradient-heavy
You need the absolute smallest file size

SVG: Avoid for Email

SVG (Scalable Vector Graphics) is perfect for websites but poorly supported in email clients. Gmail strips SVG entirely. Outlook does not render it. Apple Mail supports it inconsistently. Never use SVG for email signature logos, even though it would be the ideal format in other contexts.

GIF: A Niche Option

GIF supports transparency (though only 1-bit, meaning edges can look jagged) and is universally supported. It works for simple logos with limited colors. However, PNG offers better transparency and quality in nearly every case.

Hosting Your Logo: Embedded vs. External

How you include the logo in your signature matters as much as the logo itself. There are two approaches, and one is clearly better than the other.

Embedded Images (Avoid This)

When you paste or drag a logo into your signature editor, most email clients embed the image as a base64-encoded string or as an inline attachment. This causes problems:

Inflated email size. The full image data travels with every email, adding 20-100KB to each message.
Attachment confusion. Recipients may see your logo listed as an attachment, which looks unprofessional and clutters their view.
Spam filter triggers. Large embedded images raise spam scores, especially when the image-to-text ratio is high.
Inconsistent rendering. Different clients handle embedded images differently, leading to broken layouts.

Externally Hosted Images (Do This)

Host your logo on a web server, CDN, or asset management platform and reference it by URL in your signature HTML:

<img src="https://assets.yourcompany.com/logo.png"
     alt="Acme Corporation logo"
     width="200"
     height="40" />

The best practice for including a logo in your email signature is to host the image externally on a reliable server or CDN and reference it by URL. This keeps your email size minimal, avoids attachment confusion, ensures consistent rendering across clients, and lets you update the logo globally without touching individual signatures.

Recommended hosting options:

Your company website or subdomain (e.g., assets.yourcompany.com/logo.png)
A CDN like Cloudflare R2, AWS S3, or Google Cloud Storage
A dedicated signature management platform like Signkit that handles hosting automatically

Avoid hosting on:

Google Drive (links frequently get blocked by email clients)
Free image hosting services (may inject ads, expire URLs, or go offline)
Personal cloud storage with authentication requirements

What About Image Blocking?

Many corporate email clients block external images by default. Recipients see a placeholder until they click "Display images." This is why alt text is critical:

<img src="https://assets.yourcompany.com/logo.png"
     alt="Acme Corporation"
     width="200"
     height="40" />

Good alt text ensures the recipient still sees your company name even when images are blocked. Keep alt text short and descriptive: your company name is sufficient.

How to Add a Logo in Outlook

Outlook Desktop (Windows)

Open Outlook and go to File > Options > Mail > Signatures
Select an existing signature or click New
Position your cursor where you want the logo
Click the image icon in the formatting toolbar
Browse to your logo file and click Insert
Right-click the inserted image and select Picture > Size
Set the width to your desired display size (150-300px)
Lock the aspect ratio to prevent distortion
Click OK, then Save

Outlook tip: Outlook for Windows uses Word's rendering engine, which can resize images unpredictably. Always set explicit pixel dimensions rather than using percentage-based sizing. If the logo appears at the wrong size after saving, edit the signature HTML directly (File > Options > Mail > Signatures > edit the .htm file in %appdata%\Microsoft\Signatures\).

Outlook on the Web (OWA)

Go to outlook.com or your Microsoft 365 webmail
Click the gear icon > View all Outlook settings
Navigate to Mail > Compose and reply
In the signature editor, click the image icon
Upload your logo or paste a hosted image URL
Click the image and drag the corners to resize
Click Save

Outlook for Mac

Open Outlook and go to Outlook > Preferences > Signatures
Select or create a signature
Drag and drop your logo file into the editor
Double-click the image to access size settings
Set width and height, then click OK

How to Add a Logo in Gmail

Go to Settings (gear icon) > See all settings
Scroll to the Signature section under the General tab
Select your signature or click Create new
Position your cursor where you want the logo
Click the image icon in the formatting toolbar
Choose a method:
- Upload: Select from your computer
- Web Address (URL): Paste a hosted image link (recommended)
- Drive: Select from Google Drive
Click the inserted logo and choose Small, Medium, or Large to adjust size
Scroll down and click Save Changes

Gmail tip: The "Web Address (URL)" method is the most reliable because it references your externally hosted logo directly. Gmail re-hosts uploaded images on its own CDN, which occasionally changes the URL and can cause inconsistencies. For a full Gmail walkthrough, see our Gmail email signature guide.

How to Add a Logo in Apple Mail

macOS

Open Mail > Settings > Signatures (or Mail > Preferences > Signatures on older macOS versions)
Select the email account and click + to create a new signature
Uncheck Always match my default message font
Open your logo in Preview or Finder
Copy the image (Cmd+C) and paste it into the signature editor (Cmd+V)
Resize by dragging the corners
Close the Settings window to auto-save

Apple Mail tip: Apple Mail renders HTML and CSS more accurately than most clients, so your logo will look great. However, recipients using Outlook may see it differently. Always test by sending a test email to different clients.

For more Apple Mail setup details, check our Apple Mail signature guide.

iOS (iPhone/iPad)

The iOS Mail app supports only plain text signatures by default. To include a logo:

Create your HTML signature with the logo on your Mac
Sync it via iCloud to your iOS device
Alternatively, use a signature management tool like Signkit that pushes HTML signatures to mobile

Troubleshooting Common Logo Issues

Logo Appears Blurry

Cause: The source file resolution matches or is lower than the display size, so retina screens render it at less than full density.

Fix: Export your logo at 2x the display dimensions. If you display at 200px wide, your source should be 400px wide. Set the HTML width attribute to the smaller display value.

Logo Is Too Large

Cause: The email client renders the image at its full source dimensions because width and height attributes are missing.

Fix: Always set explicit width and height in the <img> tag. Do not rely on the email client to auto-scale.

<!-- Correct: explicit dimensions -->
<img src="logo.png" alt="Acme" width="200" height="40" />

<!-- Wrong: no dimensions, will display at full size -->
<img src="logo.png" alt="Acme" />

Logo Shows as an Attachment

Cause: The image is embedded (base64 or CID attachment) rather than hosted externally.

Fix: Upload your logo to a web server and reference it by URL instead of pasting it into the editor. See the hosting section above.

Logo Does Not Appear (Broken Image Icon)

Cause: The image URL is inaccessible. Common reasons include authentication-required hosting (Google Drive), expired URLs, CORS restrictions, or HTTP (not HTTPS) URLs.

Fix: Verify the image URL loads in an incognito browser window. Ensure the URL uses HTTPS. Use a permanent, publicly accessible host.

Logo Looks Different in Outlook vs. Gmail

Cause: Outlook for Windows uses Word's rendering engine, which handles images, spacing, and CSS differently from browser-based clients like Gmail.

Fix: Use table-based HTML layouts with inline styles. Set explicit pixel dimensions on all images. Avoid CSS properties like max-width, object-fit, or float, as Outlook ignores or misinterprets them. For more on structuring your signature for cross-client compatibility, check our email signature dimensions guide.

Logo Has a White Box Around It

Cause: The logo file has a white background instead of a transparent one, making it visible against colored or dark-mode email backgrounds.

Fix: Export your logo as a PNG with a transparent background. If your design tool exports with a white fill by default, disable the background layer before exporting.

Best Practices Checklist

Follow this checklist every time you add or update a logo in an email signature:

Export at 2x display dimensions for retina sharpness
Use PNG format with a transparent background
Keep file size under 50KB by optimizing with TinyPNG or Squoosh
Host externally on your website, CDN, or signature management tool
Set explicit width and height in your img tag
Include descriptive alt text with your company name
Use HTTPS URLs for the hosted image
Test in Outlook, Gmail, and Apple Mail before rolling out
Lock the aspect ratio so the logo never gets stretched
Update the logo everywhere when your brand refreshes

Managing Logos Across a Team

When one person adds a logo to their signature, the process is straightforward. When 50 or 200 people need the same logo, placed consistently, sized correctly, and updated simultaneously when the brand refreshes, it becomes a coordination problem.

Common issues with manual logo management:

Employees use outdated logo versions
Sizing varies from person to person
Some embed the logo, others link to different hosts
Brand refreshes take weeks to roll out

Centralized signature management solves this by letting an admin set the logo once in a template, then push it to every team member automatically. When the logo changes, one update propagates to the entire organization.

Signkit handles logo hosting, sizing, retina optimization, and cross-client compatibility so your team does not have to think about it. Upload your logo once, apply it to a template, and every signature stays on brand.

Frequently Asked Questions

What size should a logo be in an email signature?

Your email signature logo should display at 150 to 300 pixels wide and 30 to 80 pixels tall, depending on the logo's aspect ratio. The source file should be double those dimensions (300 to 600 pixels wide) for sharp rendering on retina screens. Keep the file size under 50KB by using PNG format and compressing with a tool like TinyPNG.

Should I use PNG or JPG for my email signature logo?

Use PNG for most logos. PNG supports transparency, preserves sharp edges on text and line art, and works universally across email clients. Use JPG only if your logo sits on a solid background, has no transparency needs, and you require the smallest possible file size. Avoid SVG entirely, as most email clients strip or ignore it.

How do I make my logo look sharp on retina screens?

Export your logo source file at exactly twice the display dimensions. If you want the logo to appear at 200px wide in the signature, create a 400px wide source file. Then set the HTML width attribute to 200. The email client scales the image down, using the extra pixels to render a crisp image on high-DPI screens.

Why does my logo show as an attachment in some email clients?

This happens when the logo is embedded directly in the signature (via base64 encoding or as a CID attachment) rather than referenced from an external URL. The fix is to host your logo on a web server or CDN and include only the URL in your signature HTML. This eliminates attachment confusion and keeps your emails lightweight.

Can I use an animated logo (GIF) in my email signature?

You can, but with limitations. Gmail, Apple Mail, and most webmail clients display GIF animations. Outlook for Windows does not; it shows only the first frame as a static image. If you use an animated logo, design the first frame to look complete and professional on its own. Keep the GIF under 200KB. For most brands, a static logo is the safer and more professional choice. See our guide on adding a photo to your email signature for more on image handling in signatures.

Key Takeaways

Use PNG format with a transparent background for the sharpest, most versatile logo rendering across all email clients.
Display between 150-300px wide and export your source file at 2x that size for retina screens. Always set explicit width and height attributes.
Host your logo externally on a CDN or web server instead of embedding it. This prevents attachment confusion, reduces email size, and makes updates easier.
Include alt text with your company name so recipients see your brand even when images are blocked.
Test across Outlook, Gmail, and Apple Mail before deploying. Outlook's Word-based rendering engine handles images differently from browser-based clients.

Add Your Logo the Easy Way

Getting a logo into your email signature should not require HTML editing or manual configuration for every team member. Signkit lets you upload your logo, choose a template, and deploy polished, brand-consistent signatures across your entire organization in minutes.

Get started with Signkit