March 2021: Mobile-First Indexing

Originally planned for September 2020, Google gave everyone a little more time to prepare for mobile-first indexing. Sometime in March 2021, Google will roll out a big update that is certain to change how websites are ranked in its search engine result pages. 

You might be thinking 'my website is responsive so I'm covered' but it is not that simple. A responsive website that adapts to different screen resolutions does not mean you are prepared for mobile-first indexing. 

Our initial plan was to enable mobile-first indexing for all sites in Search in September 2020. We realize that in these uncertain times, it's not always easy to focus on work as otherwise, so we've decided to extend the timeframe to the end of March 2021. At that time, we're planning on switching our indexing over to mobile-first indexing.
Google, Wednesday, July 22, 2020

What you need to do before March 2021 mobile-first indexing 

Google has given us web designers and developers loads of tips so there really isn't any excuse. Here are a few things you can look at to make sure you are prepared for mobile-first indexing.


In the earlier days of responsive web design it was common for web designers, developers and copywriters to create desktop and mobile versions of content. Things like shortened headlines and paragraphs, fewer images, hide/expand features and removing video all seemed to make sense. Less screen space meant we could make things look clean and 'fit' - heck, everyone used desktop anyway. As mobile use grew along with screen size, and browsing was painfully slow on mobile this way of thinking quickly changed. If your content is important enough for desktop, it is important enough for mobile. A lot of us web designers even took a mobile-first approach to web design and started designing from the smallest screen size up. 

The important thing is that the Google bot will crawl your website from a smart phone, and not index you based on your desktop site.

  • Make sure your headlines and markup (H1, H2) remain the same on mobile
  • Do not make a user expand to see mobile content as Google may not expand to see when crawling
  • Ensure all images, video and other media are present and optimised on mobile including alt tags

Different URLs

If your mobile site is standalone from desktop you may use different page slugs. I'd recommend comparing the mobile and desktop pages and ensuring they match where possible along with your robots file to ensure indexing is not problematic. I'm sure the last thing you want is your organic traffic disappearing overnight. 

Looking at image paths is also something Google mentions in its array of advice when preparing for mobile-first indexing. Image optimisation is a big thing when it comes to mobile performance. Web developers often use image source sets now and if that's the case, you should be fine. On the other hand, if your mobile image optimisation solution was to use a different image altogether, you could run into some issues. Google said that as it will crawl your mobile images for the first time, and ignore your desktop version, image search traffic could take a hit whilst your new URLs are being indexed. Google also advised people to see if they can implement the same URLs for images across desktop and mobile to mitigate this issue. 

Image Optimisation

Image optimisation often keeps web developers awake at night when trying to hit the page speed score target. Luckily for us, we partnered with IMGIX to handle images on desktop, mobile and everything in between. 

Google is very quick to flag images that are too big on your site but if you are using small, thumbnail-like versions on your mobile website you could face issues with Google indexing them. If images are seen to be too low quality or resolution, Google isn't going to be a huge fan. 

May 2021: Google Page Experience

We did a relatively deep dive into this subject back in November 2020 which you can read on our Google Page Experience Signals blog. In summary - speed, speed, and more speed. This subject is definitely one for the web developers to action but digital marketers and website owners in general need to know about it, demand it from their agency, and ensure they do not get left behind. 

If all this talk about SEO, development performance and mobile-first indexing makes you shiver, we're here to help. 

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