Resize Images for Email – The Right Dimensions and Format

Images in email cause more problems than in any other medium. Too large and they bounce; too wide and they break layouts; wrong format and they don't display. This guide covers how to correctly resize images for email for both attachments and inline use.

Email image attachments

For images sent as attachments:

• Target file size: Under 2 MB per attachment. Many email providers (Gmail, Outlook) reject attachments over 10–25 MB total. If forwarded repeatedly, each hop can compress further.
• Practical safe size: Under 1 MB per image for reliable delivery.
• Format: JPG is universally compatible. Avoid WebP for email attachments — some older email clients don't support it.
• Dimensions: 1280 × 720 px or smaller. Most recipients view images at screen resolution, so 4000 px photos are wasteful.

To achieve this: resize your photo to 1280 × 720–960 px as JPG. Result: typically 150–400 KB — well under the 2 MB threshold.

Inline images in HTML email templates

When embedding images in HTML email newsletters:

• Email body width: Most email clients render at 600 px wide. Images wider than 600 px may overflow on some clients.
• Hero/banner image: 600 px wide, any height. JPG recommended.
• Product thumbnail in email: 200 × 200 px to 300 × 300 px.
• Logo in email header: 200 × 60 px to 300 × 100 px, PNG (for transparency).

File size matters for email load time. Aim for:

• Hero image: under 100 KB
• Product thumbnails: under 30 KB each
• Total email image weight: under 500 KB

Format recommendations for email images

• JPG: Best for photographs in email. Universal support. Avoid for logos (artifacts on text).
• PNG: Best for logos, graphics with text. Larger than JPG for photos.
• WebP: Not recommended for email — poor support in older Outlook versions and some mobile clients.
• GIF: Supported everywhere. Use only for simple animations; static GIFs are larger than PNG/JPG.

How to resize images for email with Resizo

1. Open Resizo in your browser — free, no account.
2. Drop your image.
3. For attachments: set width to 1280 px, select JPG.
4. For email body images: set width to 600 px, select JPG.
5. For logos: keep at 200–300 px wide, select PNG.
6. Download and attach to your email or upload to your ESP.