Reduce PNG Size for Email – The Right Way

PNG files are often unnecessarily large for email use. A PNG logo in an email signature might be 500 KB when it should be 10 KB. A PNG photo attachment might be 3 MB when 200 KB would suffice. This guide shows you how to reduce PNG size for email effectively.

Why PNG files are too large for email

PNG uses lossless compression — it stores every pixel precisely. For photographs, this results in files 5–15× larger than JPG. For logos at full resolution, a 500 × 200 px PNG might still be 100–500 KB if the original was high-resolution and was just resized down.

Approach 1: Reduce dimensions (most effective)

Most email PNG files are much larger than needed for display:

• Email signature logo: 200 × 80 px is enough. A logo uploaded at 1000 × 400 px and "displayed small" is still downloaded at full resolution.
• Inline images in email body: Email clients render at 600 px wide. Any image wider than 600 px is wasteful.
• Photo attachments: 1280 × 960 px JPG is sufficient for most recipients.

Approach 2: Convert PNG to JPG

If the PNG is a photograph without transparency, converting to JPG reduces size by 80–95%:

• PNG photo at 1200 × 800 px: ~2 MB
• Same image as JPG quality 80: ~150–250 KB

Important: JPG doesn't support transparency. If your PNG has a transparent background, don't convert to JPG unless the background becoming white is acceptable.

Approach 3: Keep PNG but optimize

For logos and icons that must stay as PNG:

• Resize to the actual display size (e.g., 200 × 60 px for an email header logo)
• Use PNG-8 (256 colors) instead of PNG-24 for simple logos — much smaller for flat-color graphics
• Convert to WebP as a smaller PNG alternative (but check email client support — some older Outlook versions don't support WebP)

Email PNG size targets

• Email signature logo: Under 20 KB (200 × 80 px PNG)
• Email body image: Under 100 KB (600 px wide JPG)
• Email attachment (single photo): Under 1 MB (1280 px JPG)
• Total email image weight: Under 500 KB for good deliverability

How to reduce PNG size for email with Resizo

1. Open Resizo in your browser — free, no account.
2. Drop your PNG file.
3. Set the target dimensions (200 px wide for email logos, 600 px for body images).
4. For photographs: select JPG output.
5. For logos with transparency: keep PNG output.
6. Download and use in your email.