Googlebot 15MB Limit on Individual Sub-resource

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15 MB GoogleBot

Googlebot is essential to have a firm grasp of Google's web crawler. One recent development that demands attention is Googlebot's 15MB limit for individual sub-resources on a web page. 

Googlebot's 15 MB limit refers to the maximum file size that Google's web crawler can process for an individual subresource, such as images, stylesheets, or scripts on a web page. This limit is necessary for website owners and developers to consider, as it can impact the crawlability and indexing of their web pages by Google's search engine.

What are sub-resources?

Subresources are those elements and components within a web page that are loaded separately from the main HTML document. These resources are essential for rendering the complete web page and include files such as images, stylesheets (CSS), scripts (JavaScript), fonts, and other media assets. 

In web development, sub-resources are integral components that contribute to a website's functionality and overall user experience. They are referenced within the HTML code using tags or attributes and are loaded asynchronously to prevent blocking the rendering of the main content. Sub-resources, like CSS and JavaScript files, enable developers to separate content from presentation and behaviour, promoting maintainability and reusability. Properly optimising sub-resources is crucial for web performance, as they can impact page load times and overall responsiveness.

Types of Sub-resources

CSS (Cascading Style Sheets)

CSS files define the visual styling and layout of web pages. They control colors, fonts, spacing, and responsiveness, ensuring a consistent and appealing design.


JavaScript files contain code that adds interactivity and dynamic behavior to websites. They enable features like form validation, animations, and responsive user interfaces.


Image files, including JPEG, PNG, and GIF formats, are essential for displaying graphics and visual content on web pages. Optimising image subresources is vital for faster page loading.


Web fonts, such as WOFF and WOFF2 formats, are subresources used to define website typography. Custom fonts enhance design and readability.

Videos and Multimedia

Multimedia sub-resources, like video and audio files, enable the integration of multimedia content, making websites engaging and informative.

Other Assets

Sub-resources can also include files like XML data, JSON data, icons (e.g., favicon.ico), and more, depending on the specific needs of a web page or application. These assets contribute to a richer user experience.

Why Does Google Implement a 15MB Limit?

Google enforces a 15MB limit on individual sub-resources as part of its efforts to ensure efficient web crawling and indexing. This limit encourages website owners to keep their sub-resources, such as images and scripts, reasonably sized, contributing to a better web experience.

Focus on Page Speed and User Experience

Google's emphasis on page speed and user experience drives the implementation of the 15MB limit. Large sub-resources can slow page loading times, frustrate users, and negatively impact their experience. By limiting the size of these elements, Google aims to promote faster, more user-friendly websites in its search results.

Crawling Efficiency

Excessive sub-resources, those exceeding the 15MB limit, can slow down crawling, impacting the speed at which Googlebot indexes web pages and potentially leading to incomplete or delayed indexing. Therefore, website owners must manage sub-resources wisely to ensure smooth crawling and optimal SEO performance. 

Impact on SEO and Website Performance

The SEO and overall performance of your website are intricately connected. By optimising your website's content, structure, and technical elements, you can enhance its SEO, increasing search engine rankings and improving user engagement.

Google Ranking

Google's ranking algorithm prioritises websites that offer a seamless user experience, relevant content, and fast loading times. Focus on these factors to ensure a higher website ranking in SERPs and attract organic traffic.

Crawl Budget Relationship

The crawl budget is the number of pages on your website that search engines like Google crawl during each visit. Optimising your site's structure, internal linking, and XML sitemaps can help ensure search engines allocate their crawl budget efficiently, resulting in better indexing and visibility for your web pages. Read more...

User Experience

Search engines aim to deliver their users the best possible results, making user experience a critical factor. A user-friendly website with easy navigation, well-structured content, and mobile responsiveness improves SEO, keeps visitors engaged, and encourages them to explore more pages.

Page Load Times

Faster-loading webpages contribute to a positive user experience and play a pivotal role in SEO. Page speed is a ranking factor; therefore, optimising images, minimising HTTP requests, and leveraging content delivery networks (CDNs) can help reduce load times, ultimately benefiting your SEO efforts.

How to Check Your Website's Sub-Resource Size?

You can check the sub-resource size of the website through any of the following ways:

Google Search Console

Google Search Console monitors the website's sub-resource sizes. To do this, log in to your Google Search Console account, select your property, and navigate to the "Core Web Vitals" report. Here, you can find information on various web vitals, including sub-resource sizes, allowing you to identify and address any issues affecting your website's performance.

Third-Party Tools

There are several third-party tools available that can help you assess your website's sub-resource size. Popular options like GTmetrix, Pingdom, and PageSpeed Insights allow you to enter the website's URL and generate detailed reports that include information on sub-resource sizes. These tools provide valuable insights into how various elements on your site contribute to its loading times, helping you optimise for better performance.

Website Auditing Software

Website auditing software is a powerful tool that systematically scans and analyses websites, identifying issues and providing actionable insights for optimisation and improved performance. It helps webmasters and SEO professionals ensure their websites run smoothly and comply with best practices. 

Optimising Sub-resources to Meet the Limit

It is necessary to analyse and prioritise sub-resources effectively to optimise them based on their impact on page load times. 

Minification involves removing unnecessary characters, whitespace, and comments from JavaScript and CSS files to reduce their size. By doing so, you can significantly improve page load times as smaller files download faster while still preserving the functionality and readability of your code.

Image compression is essential for reducing the size of image files without compromising quality. Utilise modern image formats like WebP, JPEG 2000, or AVIF, which offer superior compression algorithms, and employ responsive image techniques to serve appropriately sized images based on the user's device and viewport to ensure a better user experience and faster loading times.

Prioritising Sub-resources for Crawl

Prioritising sub-resources involves determining the order in which elements like images and scripts are fetched during web crawling, optimising page loading speed, and resource utilisation.

Identifying Critical Resources for Rendering

Identifying critical resources means pinpointing the assets necessary for initial webpage rendering, ensuring that essential content loads quickly for a better user experience.

Lazy Loading and Deferred Loading Strategies

Lazy loading delays the loading of non-essential resources until they are needed, while deferred loading postpones the retrieval of certain assets to improve page load performance and interactivity.

Common Mistakes To Avoid

Some common mistakes that should be avoided are:

Oversized Media Files

Avoid excessively large media files on your website as they can slow down page loading times, impacting user experience and SEO.

Redundant or Unused Sub-resources

Eliminate unnecessary sub-resources like scripts, stylesheets, or images to reduce HTTP requests and optimise your site's performance.

Lack of Browser Caching

Implement browser caching to store static resources locally, reducing server load and improving page load speed for returning visitors.

Handling large Files and Media

Whether you are dealing with video files, high-resolution images, or other multimedia content, efficient management and distribution of large files and media is essential. Here are some strategies for handling large files and media:

Video Compression

Use video codecs like H.264, H.265 (HEVC), or VP9 to compress video files while maintaining quality. Adaptive bitrate streaming can further optimise video delivery by adjusting the quality based on the viewer's internet connection.

Image Optimisation

Employ image optimisation techniques for large images, including resizing, format conversion (e.g., WebP), and lazy loading. It ensures faster loading times and improved user experience.

Content Delivery Strategies

Choose a content delivery strategy that suits your specific needs, such as using a Content Delivery Network (CDNs), which is important in optimising media delivery by distributing content to edge servers strategically located worldwide. Users can access content from a server geographically closer to them, reducing latency and improving load times.

Metadata Management

Efficiently manage metadata associated with media files, including titles, descriptions, tags, and copyright information. It helps with content searchability and copyright compliance.

Cloud Storage

Storing large files in the cloud, such as on platforms like Amazon S3, Google Cloud Storage, or Microsoft Azure Blob Storage, can provide scalability and accessibility. 

Testing and Monitoring Your Website

Testing and monitoring your website is critical to maintaining its performance, functionality, and user experience. Here are some key considerations for testing and monitoring your website:

Regular Check of Sub-resources Sizes

It is essential to periodically assess sub-resources sizes like images, scripts, and stylesheets on your website to ensure efficient loading times. Optimising these sub-resources through compression and minification can improve website performance and user experience.

Using Google's Mobile-Friendly Test

Utilising Google's Mobile-Friendly Test tool allows you to evaluate your website's mobile compatibility, ensuring it renders well on smartphones and tablets. It helps enhance user satisfaction, search engine rankings, and overall mobile usability.

Cross-Browser and Cross-Device Testing

Your website should function consistently across web browsers (e.g., Chrome, Firefox, Safari) and devices (e.g., desktop, tablet, mobile). Testing on various platforms helps guarantee a seamless experience for all users.

Impacts On SEO Rankings and User Experience

Efficient sub-resource optimisation has a dual impact on websites, benefiting both SEO rankings and user experience. Websites can increase their rankings in search engine results by reducing page load times and improving overall performance, as search engines prioritise fast-loading sites. Simultaneously, a faster and smoother user experience enhances visitor satisfaction, reduces bounce rates, and increases user engagement, improving retention and conversions.

Future-proofing Your Website

Future-proofing your website involves proactively anticipating changes in Google's crawling and indexing limits.

Preparing For Potential Googlebot Limit Changes

As Googlebot is responsible for indexing web pages, and its limits can change over time, you must prepare, regularly monitor your website's crawl stats in Google Search Console, optimise your site's structure and content for efficient crawling, and stay informed about any announcements or updates from Google regarding changes to crawling limits. It ensures that your website remains accessible and indexable by search engines, even as their crawling behavior evolves.

Staying Updated with Google's Guidelines

To maintain a resilient website, stay informed about Google's evolving SEO and web development guidelines. Adhering to the latest recommendations and best practices will help your site remain relevant and search engine-friendly.

Alternative Crawling Solutions

When it comes to crawling websites for search engine optimisation (SEO) and indexing purposes, various methods and tools are available beyond the traditional Googlebot desktop version.

Googlebot's Mobile Version

Employing Googlebot's mobile version for crawling ensures mobile-friendly content optimisation, potentially boosting mobile search rankings, enhancing user experiences, and addressing mobile compatibility issues. This approach caters to the growing mobile user base and helps websites remain competitive in the mobile search landscape.

Fetch and Render Testing

By incorporating Fetch and Render Testing into your website optimisation strategy, you can assess how search engine crawlers interpret your web pages, identify indexing and rendering issues, and make necessary adjustments to improve your site's search engine visibility and overall SEO performance. This approach ensures your website is effectively crawled and indexed, enhancing its ranking potential.

Expert Tips and Best Practices

Gain valuable insights and recommendations from seasoned web developers and SEO professionals to enhance your website's performance and visibility in search engines. Discover the latest strategies and techniques to stay ahead:

Insights for Web Developers and SEO Professionals 

Access valuable knowledge and practical insights tailored for web developers and SEO experts. Learn about cutting-edge technologies, industry trends, and effective strategies to optimise websites for search engines while providing an exceptional user experience.

Balancing Sub-Resource Optimisation with User Experience

Find the delicate equilibrium between optimising sub-resources like scripts, stylesheets, and images for faster website loading and ensuring a seamless user experience. Strike the right balance to improve site performance without compromising user satisfaction.

Understanding Googlebot's 15MB limit on individual sub-resources for web developers and SEO professionals is important. By optimising files such as scripts, stylesheets, and images, we ensure that our websites load swiftly and facilitate efficient crawling and indexing by search engines. This optimisation directly impacts a site's search engine rankings and user experience. Regularly monitoring and adapting to evolving guidelines is crucial to gain visibility online.

Ready to conquer Googlebot's 15 MB limit on individual sub-resources? Dive into our blog for expert insights and actionable strategies, and get in touch with Webzyro to unlock peak SEO performance and ensure your website loads seamlessly. 

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