Key Rule: Use 2x Resolution
Always create images at 2x the display size for sharp rendering on retina/HiDPI screens. A 100×100px display photo should be 200×200px in the file. Then compress aggressively to keep file size small.
Email Signature Image Size Reference
| Element | Display Size | Max File Size | Format |
|---|---|---|---|
| Profile/headshot photo | 100 × 100px | Under 20KB | JPG/PNG |
| Company logo | 200 × 60px | Under 15KB | PNG (transparent) |
| Banner/promotional image | 600 × 150px | Under 40KB | JPG/PNG |
| Social media icons | 20 × 20px each | Under 5KB each | PNG |
| Divider/separator | 600 × 2px | Under 2KB | PNG |
Why Email Signature Image Size Matters
Email signatures are sent with every email you send. If your signature contains large, unoptimized images, every email you send is heavier — which can trigger spam filters, slow down delivery, and frustrate recipients on slow connections.
The total weight of all images in your email signature should be under 100KB. This ensures fast loading in all email clients and avoids spam filter triggers. With proper optimization, a professional signature with a photo, logo, and social icons can easily stay under 50KB.
Step-by-Step: Optimize Email Signature Images
- Profile photo: Use our Image Resizer to resize to 200×200px (2x for retina). Then use our Image Compressor at 80% quality to get under 20KB.
- Company logo: Resize to 400×120px (2x). If your logo has a transparent background, keep it as PNG. Compress to under 15KB.
- Banner image (optional): Resize to 1200×300px (2x for 600×150px display). Compress to under 40KB at 75% quality.
- Host images online: Upload to your website server or a CDN. Reference via URL in your signature HTML — don't embed images directly.
- Test in multiple clients: Check your signature in Gmail, Outlook, and Apple Mail. Images may render differently across clients.
Email Client Compatibility
Gmail
Supports: JPG, PNG, GIF
Blocks images by default for unknown senders. Use linked images.
Outlook (desktop)
Supports: JPG, PNG, GIF
Does not support WEBP. Linked images preferred over embedded.
Apple Mail
Supports: JPG, PNG, GIF, WEBP
Best image support. Renders retina images correctly.
Outlook (web)
Supports: JPG, PNG, GIF
Similar to desktop Outlook. Avoid WEBP.
Mobile clients
Supports: JPG, PNG
Keep images small. Mobile screens are smaller — 100×100px is plenty.
Frequently Asked Questions
What is the ideal image size for an email signature?
For a profile photo in an email signature, 100×100px at under 20KB is ideal. For a company logo, 200×60px at under 15KB. Keep total signature image weight under 100KB to avoid triggering spam filters.
Why do email signature images appear blurry?
Blurry email signature images are usually caused by using images that are too small and getting stretched. Use 2x resolution (200×200px for a 100×100px display size) to ensure sharp rendering on retina displays.
Should I embed images in email signatures or link to them?
Linking to hosted images (via URL) is better for email signatures. Embedded images increase email file size and are often blocked by email clients. Host your signature images on your website or a CDN.
What format should I use for email signature images?
Use PNG for logos (supports transparency, sharp edges) and JPG for profile photos (smaller file size). Avoid WEBP — it's not supported by Outlook and many corporate email clients.
How do I make my email signature image not appear as an attachment?
Use linked images (hosted on a server) rather than embedded images. Embedded images often appear as attachments in some email clients. Reference the image via a URL in your signature HTML.
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