Why is the 32 KB file size limit so important for BIMI SVG images?

The 32 KB file size limit is crucial because email clients, like Gmail and Yahoo Mail, need to load and render BIMI logos quickly to prevent slowing down the user experience. Larger files can cause delays or outright rejection of the logo, meaning your brand image won't appear.

Can I use a transparent background for my BIMI SVG logo?

No, it is strongly recommended to use a solid background color for your BIMI SVG image. Transparent backgrounds can lead to inconsistent rendering or visibility issues depending on the email client's interface and background themes. A solid background ensures your logo is always clearly visible.

What happens if my SVG image doesn't have a 1:1 aspect ratio?

If your SVG image doesn't have a 1:1 (square) aspect ratio, it may appear stretched, squashed, or poorly cropped in email clients. Email clients often display BIMI logos in square, rounded square, or circular containers, so a 1:1 ratio ensures your logo adapts well to all these shapes without distortion, maintaining brand consistency.

Do I need special software to create a BIMI-compliant SVG?

While you can use standard graphic design software like Adobe Illustrator or Inkscape to create the initial SVG, you may need to manually optimize the file. This often involves ensuring the baseProfile="tiny-ps" attribute is present, adding a element, and removing unsupported elements to meet the strict BIMI specifications .

What is the recommended size for a BIMI SVG image? - BIMI - Email authentication - Knowledge base

When setting up Brand Indicators for Message Identification (BIMI), ensuring your SVG logo meets the correct specifications is crucial for successful display. The size of your BIMI SVG image isn't about traditional pixel dimensions as much as it is about file size, aspect ratio, and proper SVG formatting. These factors directly impact how your brand logo appears next to your emails in supporting inboxes like Gmail.

The primary goal is to have a logo that is lightweight, scalable, and renders consistently across various email clients and devices. If your SVG file is too large or incorrectly formatted, it can prevent your brand logo from appearing, defeating the purpose of BIMI. Getting this right is a key step towards leveraging email authentication for brand visibility and trust.

Understanding the specific requirements for an SVG image to be BIMI compliant will help you avoid common pitfalls. This article will guide you through the recommended sizes, aspect ratios, and essential technical considerations to ensure your BIMI logo displays perfectly.

Key BIMI SVG size requirements

The most critical size requirement for a BIMI SVG image is its file size, which should be no more than 32 kilobytes (KB)

. This limit is imposed by mail providers like Google and ensures quick loading and rendering of your logo. While SVG is a vector format, meaning it scales without pixelation, complex designs with many paths or embedded raster images can quickly exceed this limit. Simplification is key.

Regarding dimensions, there isn't a strict minimum or maximum pixel size because SVG images are resolution-independent. However, it's generally recommended that the image should render clearly at small sizes, typically around 96x96 pixels or larger if width and height attributes are explicitly defined. The important aspect is that the visual design remains clear and recognizable, even when displayed as a small avatar.

BIMI SVG file checklist

File size: Keep your SVG file under 32 KB for optimal performance and acceptance by email clients like Gmail and Yahoo. Refer to the BIMI Group's specifications.
Dimensions: While vector, ensure the design is clear and recognizable at smaller display sizes. If specified, dimensions of 96x96 pixels or larger are good.
Aspect ratio: Maintain a 1:1 (square) aspect ratio, with the logo centered, for consistent rendering across platforms.
Background: Use a solid, non-transparent background to ensure visibility and avoid display issues.
Accessibility: Include a <desc> element within your SVG for a textual description of the logo.

Aspect ratio and visual consistency

A crucial recommendation for BIMI SVG images is to use a square aspect ratio (1:1). Although SVG images are scalable, email clients display BIMI logos in various shapes, including squares, rounded squares, and circles. By designing your logo within a perfect square and ensuring it's centered, you guarantee optimal display regardless of the recipient's email client. This prevents your logo from appearing cropped or distorted.

The idea is that your logo should fit comfortably within the smallest common display area, which is often a circular or square avatar space. While the BIMI Group states that image sizes are not an issue with vector-based SVG images, their rendering at all sizes depends on the initial design adhering to these basic principles. You can find more details on recommended SVG dimensions for BIMI in our other resources.

When you design your logo, ensure there's adequate padding around the primary visual element. This prevents it from appearing too cramped when cropped into a circular or rounded-square display. A solid background color, rather than transparency, is also advised to maintain visual integrity across diverse client interfaces.

Technical considerations for SVG files

Beyond size and aspect ratio, several technical factors within the SVG file itself are vital for BIMI compliance. The SVG must be a static, standalone file without any external references or scripts. Mail clients prioritize security, so any dynamic content, animations, or links within the SVG will cause it to be rejected. The image format required for BIMI logos is specifically SVG Tiny P/S, a more restricted profile of SVG.

It's also essential to include an <desc> (description) element within your SVG file for accessibility purposes. This provides a textual description of your logo for users with visual impairments or those using screen readers. Additionally, ensuring your SVG is served over HTTPS is critical for security and adoption.

Example BIMI compliant SVG structurexml

<svg width="100" height="100" viewBox="0 0 100 100" version="1.2" baseProfile="tiny-ps"
     xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
  <title>Your Company Logo</title>
  <desc>A descriptive text of your company logo.</desc>
  <rect width="100%" height="100%" fill="#FFFFFF"/>
  <!-- Your logo path data goes here -->
  <path d="M50 0 L100 50 L50 100 L0 50 Z" fill="#000000"/>
</svg>

One often overlooked attribute is the baseProfile="tiny-ps" attribute within the <svg> tag. This specifies the SVG Tiny Portable/Secure profile, which is a restricted subset of SVG designed for security and simplicity. Many SVG editors export standard SVG, so you might need to manually edit the file to add this attribute and remove any unsupported elements to validate your BIMI SVG.

Lastly, ensure your SVG uses a consistent XML namespace. The standard is xmlns="http://www.w3.org/2000/svg". Deviations can lead to parsing errors by mail servers and ultimately prevent your logo from appearing. Pay close attention to these technical details, as they are just as important as the visual aspects of your logo.

Monitoring and ensuring BIMI compliance

Once your BIMI SVG is created and configured, ongoing monitoring is essential to ensure it continues to display correctly. Email authentication protocols like DMARC are the foundation of BIMI, as your domain must be enforcing a DMARC policy at quarantine or reject for BIMI to work. DMARC monitoring gives you visibility into your email ecosystem, helping you verify that your emails are authenticating properly.

Challenges without monitoring

Delayed detection: Issues with SVG size or formatting might go unnoticed for extended periods.
Inconsistent display: Your logo could appear correctly in some inboxes but fail in others, creating an inconsistent brand experience.
Security risks: Without proper DMARC oversight, your domain remains vulnerable to spoofing, impacting your brand's trust.

Benefits with Suped DMARC monitoring

AI-powered insights: Get actionable recommendations to fix authentication issues affecting BIMI.
Real-time alerts: Be notified immediately if your BIMI logo or DMARC compliance encounters problems.
Unified platform: Monitor DMARC, SPF, DKIM, and deliverability from one central dashboard.

Tools like Suped provide comprehensive DMARC reporting and monitoring, which is indispensable for ensuring your BIMI deployment remains robust. We offer a generous free plan that helps you understand your email authentication status and receive alerts for any issues. This allows you to quickly identify if your SVG is failing to load or if there are underlying DMARC issues affecting delivery, helping you safely transition your DMARC policy to enforcement.

Optimising your BIMI logo for impact

In summary, the recommended size for a BIMI SVG image is less about specific pixel dimensions and more about adhering to a maximum file size of 32 KB and maintaining a 1:1 (square) aspect ratio. Technical attributes like the baseProfile="tiny-ps" and the <desc> element are equally vital for successful implementation. By following these guidelines, you ensure your brand logo displays correctly and effectively across all supporting email clients.

Implementing BIMI correctly enhances your brand's visibility and boosts recipient trust, making your emails stand out in the inbox. Combine your properly sized and formatted SVG with a strong DMARC policy for maximum impact on your email deliverability and brand reputation.