📧 Email Image Guide
Reduce Image Size for Email
Email clients don't support WebP — use compressed JPG or PNG. Keep each image under 200 KB, stay under 1 MB total, and use 600 px wide layouts. Larger images slow load times, trigger spam filters, and reduce open rates.
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Compress JPG and PNG images for email without quality loss.
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Email Image Format Support (2026)
Important: Do NOT use WebP in email. Major email clients including Outlook, Apple Mail, and Gmail do not support WebP. Sending WebP images will result in broken images for a large percentage of your recipients.
| Email Client | JPG | PNG | WebP | GIF |
|---|
| Gmail (web) | ✓ | ✓ | ✗ | ✓ (animated) |
| Apple Mail | ✓ | ✓ | ✗ (most versions) | ✓ |
| Outlook 2019/365 | ✓ | ✓ | ✗ | Static only |
| Outlook web (OWA) | ✓ | ✓ | ✗ | ✓ |
| Yahoo Mail | ✓ | ✓ | ✗ | ✓ |
| Thunderbird | ✓ | ✓ | ✗ | ✓ |
| Samsung Mail | ✓ | ✓ | ✗ | ✓ |
Bottom line: JPG for photos, PNG for graphics and logos. WebP is for websites, not email.
Email Image Size Targets
Max per image
<200KB
Images over 200KB slow load times and may trigger spam filters
Total email size
<1MB
Including all images, HTML, and CSS. Heavy emails go to spam.
Image width
600px
Standard email column width. Use max-width:100% for mobile scaling.
Gmail HTML clip
102KB
Gmail clips and hides emails with HTML over 102KB — keep HTML lean.
How to Compress Email Images
1
Resize to 600px wide
Don't use full-resolution photos. Resize to 600 px wide (or 300 px for two-column layouts) before compressing.
2
Choose format
JPG for photos (quality 80–85). PNG for logos, screenshots, graphics with text. Never WebP — email clients don't support it.
3
Compress with Convertlo
Drop your resized JPG or PNG into Convertlo's compressor. Reduce to under 200 KB per image without visible quality loss.
4
Host externally
Upload images to your CDN or hosting service. Link them in your email HTML — don't embed (inline/base64). External hosting is standard for email campaigns.
Email Image Best Practices
Alt Text
Alt text is critical — 50% of opens block images
About half of email opens have images blocked by default (corporate security, slow connections). Without alt text, your email is a blank white rectangle to those readers. Write descriptive alt text for every image.
No Inline Images
Host images externally, not inline
Inline (embedded/base64) images massively inflate email size — a 100 KB image becomes ~133 KB as base64. Always host images on a server/CDN and link them via URL in your email HTML.
Spam Filters
High image-to-text ratio = spam flag
Emails that are mostly images with little text are flagged as spam by many filters. Maintain a text-to-image ratio of at least 60% text. Don't send image-only emails.
Retina
2× retina images at half the display size
For crisp images on high-DPI screens: use an image that's 2× the display dimensions but set width and height to the display size. A 600 px display image should be 1200 px wide in the src.
CTA Images
Use HTML buttons, not image-based CTAs
If your call-to-action is an image, it disappears when images are blocked. Use bulletproof HTML/CSS buttons (background color, border) for CTAs. Reserve images for visual content, not actions.
Dimensions
Always specify width and height attributes
Add width and height on every <img> tag. Without them, the layout collapses while images load — especially noticeable in Outlook.
Frequently Asked Questions
What image format should I use for email?
JPG for photographs (quality 80–85) and PNG for graphics, logos, and images with text or transparent backgrounds. Do NOT use WebP — Outlook, Apple Mail, Gmail, and Yahoo Mail all lack WebP support. GIF is acceptable for simple animations, but is larger than PNG for static images.
Can I use WebP images in email?
No. WebP is not supported by Outlook (any version), Apple Mail, Gmail, Yahoo Mail, or Samsung Mail — which together account for the majority of email opens. Sending WebP in email results in broken images for most recipients. Always use JPG or PNG in email campaigns.
What is the maximum image size for email?
Keep each image under 200 KB and total email under 1 MB. Gmail clips emails with HTML over 102 KB (a separate limit from image file size — this refers to the raw HTML+CSS). For image-heavy promotional emails, keep each image under 100 KB if possible. Images are hosted externally and loaded when the email is opened, so smaller = faster load time.
Does image size affect email deliverability?
Yes. Large, image-heavy emails are more likely to be flagged as spam because: (1) spam filters associate high image-to-text ratios with spam marketing, (2) slow-loading images reduce engagement rates (clicks, opens) which inbox providers track, (3) very large emails may be blocked entirely by some security filters. Keep total email under 1 MB and maintain at least 60% text content.
What width should email images be?
600 px for single-column emails (the email standard). 280 px for two-column grid layouts. For mobile, add max-width: 100% in your CSS so images scale down — most email clients on mobile render at 320–414 px wide. Set explicit width and height HTML attributes to prevent layout collapse during loading.