How to Compress Images for Email Signatures (Outlook, Gmail — 2026)
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Quick Answer
Email signature images must be small and dimensionally correct. Target: 200–300px wide, under 50KB, JPG or PNG (PNG for logos with transparency). Outlook 2021+ and Gmail both display signature images inline — large images (over 100KB) cause email clients to show them as attachments, not inline. The goal is under 50KB at 200px wide for a logo, or under 100KB at 300px for a photo-plus-logo signature.
Step-by-step
- 1
Resize your signature image to 200×100px for logos, or 300×150px for logos with tagline/contact.
- 2
For logos with transparency (PNG): export as PNG 24-bit, optimize losslessly. Target under 30KB.
- 3
For photo headshots in signatures: export as JPG quality 85, resize to 80×80px circle-crop if used as avatar. Target under 20KB.
- 4
For banner-style signatures: max 600px wide, export as JPG quality 80, under 100KB.
- 5
Upload to your email client: Gmail → Settings → Signature / Outlook → Options → Signatures. Paste or upload the image.
- 6
Test by sending an email to yourself — check that the image appears inline (not as an attachment) in multiple clients.
Expected output
Format
PNG for logos with transparency, JPG for photos and banners
Quality setting
PNG lossless under 30KB / JPG quality 80–85 under 50KB
Estimated size
Logo: 15–30KB / Photo: 15–20KB / Banner: 50–100KB
Why you might need this
- →Corporate email signatures — logo at 200×100px under 30KB inline in Outlook and Gmail
- →Real estate agent signatures — headshot + logo combo, under 100KB total
- →Law firm email footers — firm logo at 200×80px, PNG with transparency on colored background
- →Freelancer signatures — personal brand logo at 250×80px under 40KB
Troubleshooting
My signature image shows as an attachment in Outlook
Image is too large (over 100KB) or embedded incorrectly. Keep under 50KB and ensure the image is embedded (not linked) in the signature editor.
Gmail signature image disappears when forwarding
Gmail uses linked images in signatures. Images must be hosted at a stable URL, not just uploaded locally. Use Google Photos or your company server.
Signature image looks blurry on retina MacBook screens
Use 2× dimensions: 400×200px for a 200×100px display size. The email client will display at 200×100px but retain retina sharpness.
Outlook 2016 does not show my PNG
Outlook 2016 has issues with certain PNG profiles. Use sRGB color profile and export without ICC profile embedding.
Signature image loads slowly for recipients
If the image is hosted (not embedded), slow servers cause delay. Embed the image directly in Outlook. For Gmail, host on a fast CDN.
Frequently asked questions
What is the best image size for an email signature?
200–300px wide, under 50KB. Signature images display at consistent 72dpi in email clients, so high resolution is wasted and causes slow loading or attachment confusion.
Should I use JPG or PNG in email signatures?
PNG for logos (preserves transparency and sharp edges). JPG for headshots and photos (smaller file at same quality). PNG logos at 200px wide should be under 30KB.
Why does my signature image show as an attachment?
Email clients show large images (over 100KB) as attachments. Keep all signature images under 50KB. Also, the image must be embedded or hosted, not a local file path.
How do I add a retina-quality image to an email signature?
Upload a 2× image (400×200px) but set the HTML img tag to display at 1× (width="200" height="100"). Email clients that support retina will display sharply; others display at 1×.