Mailchimp Email Image Sizes and Optimisation Guide

The practical answer: prepare a 660px full-width image for Mailchimp's newer email builder, or a 1320px source when you need a sharper 2x asset.

Legacy templates commonly use a 600px layout. Always size the artwork for the actual image block, not simply the overall email width.

Mailchimp image widths depend on the email builder

Mailchimp's current image-block documentation recommends a minimum image width of 660px for its newer email builder. Its separate legacy template documentation describes layouts that are generally 600px wide. These are builder-specific recommendations, not contradictory instructions for the same design.

The working width can also change when a block has internal padding, multiple columns or a smaller alignment setting. A 660px email does not mean that every logo, product image and supporting graphic should also be 660px wide.

Mailchimp placement	Typical display width	Possible 2x source
New builder full-width banner	660px	1320px
Legacy builder full-width banner	600px	1200px
Two-column new-builder image	Approximately 300px to 330px	Approximately 600px to 660px
Email header logo	Approximately 160px to 240px	Approximately 320px to 480px

Column examples are practical starting points. Measure the usable space because padding and gutters reduce the available width.

Choose image dimensions for each Mailchimp content block

Mailchimp's image block offers display options including Original, Fill and Scale. Fill can expand an image across its content area, while Scale changes its visible size within the layout. These controls adjust presentation, but an unnecessarily large source file may still take longer for subscribers to download.

Match full-width hero artwork to the current 660px or legacy 600px layout.
Calculate smaller product-image widths from the actual column and padding.
Leave sufficient clear space around logos and promotional text.
Choose a dedicated crop when a landscape desktop banner becomes difficult to read on a phone.
Add meaningful alternative text using the image block's Alt Text field.

Background image caution: Mailchimp notes that background images in multi-column sections can appear distorted on mobile. Use a simpler single-column layout where practical and provide a suitable fallback background colour.

Prepare 1320px Mailchimp Retina artwork without oversizing the layout

A high-density image contains more source pixels than the width at which the email displays it. For the newer builder, a 1320 × 660px file can appear inside a 660 × 330px banner area. For a legacy 600px design, a 1200 × 600px source can serve the same 2x purpose.

Do not make the visible banner 1320px wide. The source image provides extra detail while the template continues to control the intended display width. Compare 1x, 1.5x and 2x versions when the larger source adds noticeable file weight.

For more worked examples, read our Retina Email Images Guide.

Review mobile display, image cropping and readability

Mailchimp's responsive layouts can scale campaign content for narrower screens. However, reducing a wide promotional banner does not automatically make small embedded text readable. Assess the actual composition at common mobile widths such as 320px, 360px, 375px and 390px.

Where the selected builder and layout support separate mobile or desktop styles, review those settings before creating alternative artwork. Keep key product details near the centre, make promotional messages sufficiently large and avoid placing essential copy against the edges.

Check both the campaign preview and a real test email. Builder previews are useful, but Gmail, Outlook and Apple Mail can interpret the final HTML differently.

Mailchimp image file size, Content Studio and file formats

Mailchimp's Content Studio documentation states that uploaded images can be up to 1MB each. Treat this as the documented upload boundary, not a recommended target for every campaign image. A suitable hero image might be considerably smaller when its visual quality remains strong.

Photographic promotion

A 1320 × 660px JPG source can support a 660px display. Optimise the photograph until the important details remain clean and colour gradients stay smooth.

Transparent brand logo

A 360 × 120px PNG can display at 180 × 60px while keeping transparent edges and sharper lettering on high-density screens.

Use JPG for most photographs and PNG for logos, transparency or precise illustrated graphics. Review the complete campaign image weight, especially when the message includes a product grid or several promotional sections.

Gmail clipping relates to email HTML, not hosted image bytes

Mailchimp explains that Gmail may clip messages when the email message size exceeds approximately 102KB. This concerns the underlying message HTML and associated markup. It does not mean that a separately hosted 150KB image automatically causes Gmail clipping.

The email contains an image tag and a URL, while the image itself is requested separately. Reducing a hosted image from 300KB to 120KB can improve download speed, but it does not remove 180KB from the email HTML.

Reduce excessive template markup, repeated blocks and unnecessary HTML to manage clipping risk.
Resize and compress hosted artwork to improve campaign loading.
Check whether copied content adds hidden formatting or redundant code.
Test the complete message instead of judging clipping from an image file alone.

A practical Mailchimp image-preparation workflow

Identify whether the campaign uses Mailchimp's newer builder or a legacy template.
Check the width of the specific image block, including padding and columns.
Choose a 1x, 1.5x or 2x source depending on the visual importance of the asset.
Export a suitable JPG or PNG and reduce the file weight while preserving visible quality.
Upload the finished image to Content Studio and insert it into the appropriate block.
Set alignment, descriptive alternative text and any relevant link.
Preview desktop and mobile layouts, then send a test to the inboxes that matter.

Our complete Email Image Size Guide explains broader layout, dark-mode and Outlook considerations. Teams comparing ecommerce-focused workflows can also read the Klaviyo email image sizes guide.

Mailchimp image mistakes that make campaigns look unpolished

Applying the legacy 600px width to every newer 660px builder design.
Uploading a camera-sized photograph and relying on the editor to make it efficient.
Using a 2x source without maintaining the correct visible display width.
Placing important sale details inside small image text that becomes unreadable on mobile.
Confusing the 102KB HTML clipping threshold with the size of an externally hosted image.
Forgetting alt text or relying on a background image without an appropriate fallback.

Frequently asked questions about Mailchimp email images

What image size does the Mailchimp email builder recommend?

Mailchimp recommends a minimum width of 660px for an image filling the content area in its newer email builder. For a sharper 2x version, prepare a 1320px source and display it at the intended content width.

Why do some Mailchimp guides recommend 600px and others 660px?

The recommendations refer to different builders. Mailchimp documents a 600px width for its legacy templates, while image guidance for its newer builder recommends 660px. Always check the builder and the actual content block.

How large can an image uploaded to Mailchimp be?

Mailchimp states that images uploaded to its Content Studio can be up to 1MB each. A file well below that limit can still be preferable if it retains acceptable quality and loads more quickly.

What size should a two-column Mailchimp product image be?

Measure the usable width of each column after allowing for padding. In a 660px layout, approximately 300px to 330px per image may be suitable. A 600px to 660px source can support a 2x display where appropriate.

Does reducing an image below 102KB prevent Gmail clipping?

No. Gmail clipping relates to the size of the email HTML message, not the file size of a separately hosted image. Smaller image files improve loading, while reducing HTML and repeated markup addresses clipping.

Should Mailchimp email images be JPG or PNG?

JPG usually suits photographs and detailed promotional banners because it can achieve smaller files. PNG is useful for logos, transparency and artwork with crisp edges or text. Compare the actual output before choosing.

Can I use different Mailchimp image designs for mobile and desktop?

Mailchimp provides mobile and desktop styling options in supported layouts and content blocks. The available controls depend on your builder and design, so preview the actual campaign and prepare alternative artwork only where the template supports it.

Official Mailchimp documentation

Builder capabilities and account requirements can change. Confirm current details against Mailchimp's published guidance.

ImageOptimise is an independent image-preparation tool and is not affiliated with or endorsed by Mailchimp.

Create clearer Mailchimp campaign images

Start with the correct builder width, prepare the right content-block dimensions and optimise the final image before uploading it to your campaign.

Open Email Image Optimizer