How do I add a logo to my email signature?

Host your logo at a public HTTPS URL (your company website, a CDN, or cloud storage set to public). In your signature HTML, add an img tag with the URL as the src attribute. Set both a width HTML attribute (e.g. width='160') and an inline CSS style (style='width:160px;max-width:160px;') to fix Outlook DPI scaling.

What format should a logo be in for an email signature?

PNG with a transparent background. PNG gives lossless compression — logos with sharp edges, text, and solid colours render crisply. SVG is not supported in desktop Outlook (any version) and many mobile email apps. JPG introduces compression artefacts on logo text and edges.

Why does my logo appear too large in Outlook?

Outlook scales images based on Windows display DPI. At 125% or 150% scaling (common on HiDPI laptops), an image set to 160px renders at 200–240px. Fix: add width='160' as an HTML attribute on the img tag (not just CSS). Outlook reads the HTML attribute for DPI override; the CSS width handles other clients.

Email Signature with Logo

A company logo in your email signature reinforces brand identity on every email sent. Getting it right requires three things: the correct dimensions and format, a public HTTPS hosting URL (Gmail and Outlook don't accept base64), and the Outlook DPI fix to prevent the logo from scaling up on high-resolution Windows displays.

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Logo Specifications

Horizontal wordmark120–200px wide, ≤50px tall

The standard range. At 160px, a wordmark sits proportionately next to 14px contact text. Going above 200px risks overflowing on mobile email views (320px viewport minus padding).

Square / icon mark40–60px square

Icon-only logos used alongside text. At 40px they're clearly recognisable. Below 32px they become unclear on standard displays.

Stacked logo80–120px wide, ≤80px tall

If your stacked logo runs tall, consider using the horizontal variant for email signatures. Tall logos push contact details far down.

File formatPNG with transparency

Lossless. Supports transparent backgrounds so the logo works on any email background colour. SVG is not supported in desktop Outlook. JPG adds visible artefacts on logo text and edges.

File sizeUnder 20KB

Compress with TinyPNG before uploading. A 160px logo PNG should be under 15KB. Large images slow down email loading and increase data usage on mobile.

Correct HTML for Logo in Email

The following pattern works across Outlook, Gmail, and Apple Mail:

width="160" — HTML attribute. Overrides Outlook DPI scaling. Required.

height="42" — Prevents layout shift while the image loads. Set to actual pixel height.

max-width:160px — Prevents overflow in narrow webmail views.

display:block — Removes the 4px phantom gap below inline images.

border:0 — Removes the blue border some email clients add around linked images.

Retina-Sharp Logos

Export your logo at 2× the display size. Set the width attribute to the display size. On standard displays the logo appears at the correct size. On retina displays it renders at double pixel density — sharp instead of blurry.

Example: display at 160px

→ Export logo-320.png at 320px wide from your design tool
→ Compress with TinyPNG (target under 20KB)
→ Host at your HTTPS URL
→ Set width="160" and style="width:160px"
→ Result: crisp logo on retina Macs, iPhones, and HiDPI Windows displays

Hosting Your Logo

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Your company website

e.g. https://yourcompany.com/assets/logo.png — the most reliable option. You control the URL and it won't change.

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CDN (Cloudinary, Cloudflare Images)

Free tiers available. Provides fast global delivery, automatic image optimisation, and stable URLs.

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Public GitHub / Vercel / Netlify

Any publicly accessible static deployment works. GitHub raw file URLs are reliable.

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Google Drive / OneDrive / Dropbox

Direct file links either require authentication or use unstable URL patterns. Avoid — links break for external recipients.

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Base64 inline

Gmail strips base64-encoded images from email signatures. This approach fails silently — the logo won't appear to Gmail recipients.

Related Guides

Add Your Logo to a Professional Signature

Paste your logo URL — SignForge applies the Outlook DPI fix automatically. Free, no signup.

Create My Signature →

Works with Gmail, Outlook, Apple Mail & more