The practical answer: start with the actual width of your email layout. Many established templates use 600px, while the current Mailchimp builder uses 660px. Export at 1x, 1.5x or 2x as appropriate, optimise the file weight and set the correct display width in the email.
There is no single image size that suits every newsletter, product grid, screen or email client.
Recommended image dimensions for email layouts
The best email image size depends on the width of the content area, the position of the image and how much detail the design needs. Begin with the display width, which is the size at which the image should appear inside the email, then decide whether a higher-density export is worthwhile.
Many legacy email templates are built around a 600px desktop container. Mailchimp states that its current email builder uses 660px templates, while its legacy templates use 600px templates. Internal padding can make the usable image area narrower than the outer template width.
| Email image placement | Typical display width | Suggested 2x width | Practical use |
|---|---|---|---|
| Standard email hero | 600px | 1200px | Legacy templates and full-width campaign artwork |
| Modern Mailchimp hero | 660px | 1320px | Current Mailchimp email builder |
| Wider custom layout | 640px | 1280px | Custom-coded or wider editorial emails |
| Two-column image | 300px to 330px | 600px to 660px | Products, offers and article cards |
| Three-column image | 200px to 220px | 400px to 440px | Product grids and compact feature blocks |
| Four-column image | 150px to 165px | 300px to 330px | Small category tiles and supporting assets |
| Mobile-first banner | 320px to 414px | 640px to 828px | Dedicated mobile layouts and narrow screens |
| Email logo | 120px to 240px | 240px to 480px | Headers, signatures and brand identification |
Mailchimp detail: the outer width and the available content block width are not always identical. Mailchimp lists a 564px full-width content area for certain legacy layouts and a 660px full-width area in the newer builder. Always check the actual block, padding and column configuration.
Our Email Image Optimizer includes practical desktop, mobile and campaign presets so you can prepare artwork at a suitable display width without calculating every size manually.
Choosing suitable email image file sizes
Pixel dimensions describe how large an image appears. File size describes how much data the subscriber must download. Both matter, but they solve different problems.
Mailchimp recommends keeping an individual campaign image to a maximum of 1MB. For routine marketing emails, smaller files are often preferable when the image still looks clean and readable.
| Asset type | Useful starting target | What to prioritise |
|---|---|---|
| Logo or small icon | 10KB to 80KB | Sharp edges, contrast and transparent background where needed |
| Product image | 50KB to 200KB | Recognisable product detail and consistent appearance |
| Promotional banner | 100KB to 300KB | Readable offer text and a clear focal point |
| Detailed hero photograph | 150KB to 400KB | Acceptable photographic detail without unnecessary pixel weight |
These ranges are practical starting points, not strict technical rules. A complex photograph may need more data, while a simple logo can be much smaller. Judge the result at the actual display size rather than chasing the lowest percentage or a fixed number.
- Crop unused space before exporting.
- Match the image width to the intended email block.
- Choose JPG for most photographs and PNG when sharp graphics or transparency matter.
- Use a reasonable density such as 1x, 1.5x or 2x instead of exporting every image at its original camera resolution.
- Check the combined weight of all images in a campaign, not just the weight of one hero banner.
Preparing Retina-friendly email images
A Retina-friendly email image contains more actual image pixels than the size at which it is displayed. This can make photography, logos and fine detail look sharper on high-density screens.
Although Retina is an Apple product term, high-density displays are also common on Android phones, Windows laptops and other devices. The underlying principle is useful beyond iPhones and iPads.
| Intended display size | 1x file | 1.5x file | 2x file |
|---|---|---|---|
| 600 × 300px hero | 600 × 300px | 900 × 450px | 1200 × 600px |
| 660 × 330px banner | 660 × 330px | 990 × 495px | 1320 × 660px |
| 330 × 330px product | 330 × 330px | 495 × 495px | 660 × 660px |
| 180 × 60px logo | 180 × 60px | 270 × 90px | 360 × 120px |
A 2x export doubles both width and height, producing four times as many pixels. That can increase the file weight, so 2x is not automatically the best choice for every image. A 1.5x export can provide a useful compromise when the campaign contains many visual assets.
Changing an image's DPI number without changing its actual pixel dimensions does not create extra visible detail. For email preparation, focus on the real pixel width, pixel height, display size and final encoded file size.
JPG versus PNG for email campaigns
JPG and PNG remain practical choices for most email campaigns because they are supported consistently across established email applications. The better option depends on the type of artwork.
Use JPG for photographs
JPG usually works well for product photography, lifestyle imagery, event photographs and visually detailed campaign banners. It can significantly reduce photographic file size while maintaining good visible quality.
Use PNG for graphics
PNG is useful for logos, illustrations, screenshots, crisp typography and images that need a transparent background. It often protects sharp edges better, although detailed photographic PNG files can become unnecessarily large.
WebP and SVG are valuable source formats for websites and design workflows, but support across email applications can be inconsistent. A practical approach is to upload those formats as source artwork and export a compatible JPG or PNG for the final email.
Use the RGB colour space for email images. Print-oriented CMYK files can render inaccurately or fail to display as expected in digital environments.
Outlook-specific email image considerations
Outlook is not a single rendering environment. Classic Outlook for Windows, the newer Outlook application, Outlook on the web and Outlook mobile can handle HTML and images differently.
Instead of relying entirely on modern CSS behaviour, provide clear image dimensions and keep the underlying email markup straightforward.
Specify the intended image width
If a 1200px file should display at 600px, make that intended display width explicit. A common email-friendly starting point is:
<img src="https://example.com/email-banner.jpg"
width="600"
alt="Autumn collection: selected styles now available"
style="display:block;width:100%;max-width:600px;height:auto;border:0;">The exact markup should still fit your email template and production standards. Some older email clients interpret responsive CSS differently, so test the final campaign rather than assuming one snippet fixes every rendering issue.
Prepare for blocked images
Microsoft explains that classic Outlook can block automatic external image downloads. This makes meaningful alternative text essential, especially for logos, promotional artwork and product images that communicate important information.
- Add useful alt text instead of repeating the file name.
- Keep essential offers and calls to action available as real HTML text where possible.
- Avoid relying on a background image alone to explain the message.
- Test the campaign in the Outlook versions used by your audience.
Preparing email images for mobile and desktop
Desktop email layouts commonly display content at 600px to 660px wide, but mobile inboxes may present the same content inside a much narrower viewport. Common mobile reference widths include 320px, 360px, 375px, 390px and 414px.
A well-built responsive email often scales a full-width desktop image down automatically. However, a smaller version of a desktop banner is not always readable on a phone.
Desktop campaign image
A 600 × 300px display area can use a 1200 × 600px file at 2x density. Keep the focal point centred and avoid tiny embedded text.
Mobile campaign image
A 375 × 250px display area can use a 750 × 500px file at 2x density. Consider a tighter crop or larger visual hierarchy when the message must stay readable.
Where your platform and template support separate mobile assets, prepare an alternative crop specifically for narrow screens. Otherwise, select an image composition that remains clear when scaled down.
The Email Image Optimizer includes both desktop and mobile presets, allowing campaign teams to compare practical output sizes before placing artwork into a template.
Dark-mode considerations for email images
Dark mode can change the surrounding email background, text colours or interface appearance. Different applications apply these changes differently, so the goal is to identify likely visibility problems before sending.
- Check logos and icons against both light and dark backgrounds.
- Use a transparent PNG when a logo should sit naturally on different background colours.
- Add a subtle outline, safe background shape or sufficient padding when a dark logo disappears against a dark surface.
- Do not rely on a white rectangular image background if the surrounding campaign may become dark.
- Keep important text readable when the surrounding interface changes.
- Test Outlook, Apple Mail, Gmail and the relevant mobile applications where possible.
Important: a light and dark preview is a useful design check, not a guarantee that every email application will reproduce colours identically. Some clients also adjust message backgrounds independently of the original HTML.
Use the light and dark previews in the Email Image Optimizer to spot contrast and transparency issues before exporting.
Practical examples for banners, promotions and products
Newsletter hero banner
Display: 600 × 300px
2x export: 1200 × 600px
Typical format: JPG for photographic artwork
Starting target: around 100KB to 300KB
Mailchimp promotional banner
Display: 660 × 330px
2x export: 1320 × 660px
Typical format: JPG or PNG depending on artwork
Starting target: around 100KB to 350KB
Two-column product image
Display: 300 × 300px
2x export: 600 × 600px
Typical format: JPG for product photography
Starting target: around 50KB to 200KB
Email header logo
Display: 180 × 60px
2x export: 360 × 120px
Typical format: PNG for transparency
Starting target: around 10KB to 80KB
Mobile campaign creative
Display: 375 × 250px
2x export: 750 × 500px
Typical format: JPG for lifestyle imagery
Starting target: around 70KB to 220KB
Three-column category tile
Display: 220 × 220px
2x export: 440 × 440px
Typical format: JPG or PNG depending on detail
Starting target: around 30KB to 120KB
Use these examples as a planning guide rather than a rigid requirement. The right outcome depends on the image content, the campaign design and the audience's viewing conditions.
Gmail message clipping and image file size are different
Gmail is widely associated with clipping email messages when the underlying HTML message becomes larger than approximately 102KB. This measurement relates to the email's HTML markup, text, links, tracking code and associated message content.
A separately hosted 200KB image does not add 200KB to the HTML message. The email HTML usually contains an image tag and a URL pointing to the hosted file. The bytes in that markup contribute to the HTML message size, while the image file itself is downloaded separately.
Reducing image file size is still valuable because smaller images can load faster and use less mobile data. It simply should not be presented as a direct fix for Gmail HTML clipping.
- To reduce HTML clipping risk, simplify excessive markup, repeated code, long tracking-heavy content and unnecessarily large email templates.
- To improve image loading, optimise image dimensions, format, density and encoded file size.
- If removing an image reduces HTML size, the saving comes from removing its associated markup, not from changing the byte size of the separately hosted image.
Frequently asked questions about email image size
What is the best image size for an email newsletter?
Match the visible width of the email content column. Many established templates use a 600px layout, while the current Mailchimp email builder uses a 660px layout. For a sharp 2x image, export at 1200px or 1320px respectively and set the intended display width in the email.
How large should an email image file be?
There is no universal limit. A practical starting range is 100KB to 300KB for a full-width banner and 50KB to 200KB for many product images. Mailchimp recommends keeping individual images at or below 1MB. Balance the file size against image complexity, accessibility and visible quality.
Should email images be 600px or 1200px wide?
Both values can describe the same image. An image can be displayed at 600px wide while its downloaded file contains 1200px of horizontal detail for 2x high-density screens. The email HTML should specify the intended 600px display width.
What size should a Mailchimp email image be?
Mailchimp states that its legacy email templates are 600px wide and its newer builder templates are 660px wide. It recommends image widths of 600px to 1200px for the legacy builder and 660px to 1320px for the newer builder, depending on the content block and desired pixel density.
Is JPG or PNG better for email marketing?
JPG is usually the more efficient choice for photographs, campaign imagery and detailed product scenes. PNG is generally better for logos, text-heavy artwork, sharp graphics and images that need transparency. Test the final appearance and file size before choosing.
Does a 102KB image make Gmail clip an email?
No. Gmail clipping is associated with the size of the email HTML message, not the file size of separately hosted images. Large hosted images can still make campaigns load more slowly, but reducing an image from 200KB to 100KB does not directly reduce the HTML message by 100KB.
What image sizes work well for mobile email?
Common mobile layout widths include 320px, 360px, 375px, 390px and 414px. A responsive full-width desktop image can scale down inside a mobile layout, or a dedicated mobile creative can be prepared when the design and email platform support separate assets.
Do Retina email images only matter on Apple devices?
No. Retina is an Apple brand name, but high-density displays are also common on Android phones, Windows devices and other screens. A 1.5x or 2x image can improve sharpness whenever the display contains more physical pixels than the image display size.
Can an image optimiser guarantee perfect Outlook or dark mode rendering?
No. Outlook versions and dark mode behaviours vary between desktop, web and mobile applications. Correct dimensions, explicit image width, clear alternative text and light or dark previews help reduce problems, but important campaigns should still be tested in the relevant email clients.
Platform guidance and further reading
Email applications and platform recommendations can change, so check current documentation before committing to a campaign template or delivery standard.
Prepare your next email image with confidence
Start with the real display width, choose an appropriate pixel density, protect visible quality and check the artwork against both light and dark backgrounds. A practical image is the one that works across your campaign, not the one with the biggest dimensions or the smallest possible file.