How to add a logo to your email signature

The difference between a crisp, professional logo and a broken image square is three technical details. Here's the right way.

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The right way, step by step

Export your logo as PNG (transparent background) about 2× its display size — e.g. 240px wide for a 120px slot — so it stays sharp on retina screens.
Host it on a public HTTPS URL — your website, or your signature tool's hosting. Never attach it or paste from a local file.
In Gmail: Settings → Signature → click the image icon → paste the URL (or pick from Drive). In Outlook: Signature editor → Insert picture.
Click the inserted logo and set its display size (Gmail: Small/Medium/Large; better: exact width in the HTML).
Send a test to yourself AND a colleague on Outlook — confirm it renders, isn't blurry, and doesn't arrive as an attachment.

Why logos break

Attached instead of hosted

Attached images show as paperclip attachments or broken squares. Hosting on HTTPS is non-negotiable.

Wrong dimensions

A 1200px logo squeezed into 120px looks fine on your screen and enormous when a client strips the sizing. Export at 2×, set explicit width.

HTTP instead of HTTPS

Modern clients block mixed content — http:// images simply don't load.

Slow host

If the image server lags, recipients see the broken-image icon. Use a CDN-backed host.

The zero-step alternative

Enter your work email in ProSignature and it fetches your real logo from your company site, sizes it correctly, hosts it on fast HTTPS, and installs the finished signature into Gmail in one click. Full sizing details: email signature image sizes.

Written and maintained by the ProSignature team. Competitor pricing and feature claims on this site are verified against each vendor's live page on the day of writing — last verified 26 July 2026. No affiliate links. How we work.

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FAQ

Frequently asked questions

What size should a logo be in an email signature?

Display at 100-150px wide (up to ~180px for wide wordmarks), exported at 2× for retina. Keep the file under 50KB.

Why does my logo arrive as an attachment?

It was embedded/attached rather than hosted. Host the image on a public HTTPS URL and reference it in the HTML.

PNG, JPG or SVG?

PNG with transparent background. SVG isn't supported by most email clients; JPG puts a white box behind your logo.

Can it link to my website?

Yes — wrap the image in a link to your homepage. Generators do this by default.

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