March 2021 signals the start of Google's long-anticipated and delayed switch to mobile-first indexing for all websites.

To coincide with the move, we have analyzed the search landscape to see how mobile and and desktop trends have taken shape in recent years, with two areas of focus to guide our study:

• To see how traffic trends and user behavior on mobile stack up against desktop, we analyzed the traffic data for the 1,000 most visited domains from Traffic Rank’s Global Reports for 2018, 2019, and 2020.
• To highlight SERP discrepancies between mobile and desktop, we took the top 50,000 keywords by search volume from the Semrush US database, and compared the search results.

Mobile vs. Desktop Study: Key Findings

• Search traffic surged by 22% in 2020 compared to 2019 for the 1,000 most visited websites in the world.
• 66% of all site visits came from mobile devices in that time.
• Bounce rates were higher and total times on site were shorter on both mobile and desktop, indicating that user engagement is growing increasingly difficult to achieve.
• Only 17% of websites retained their positions across both mobile and desktop SERPs, and 37% of URLs were actually thrown out of the top-10 when the search query was made from a mobile device.

Let’s delve into those findings in more detail and look at what they could mean for you.

Global Search Traffic Trends

Comparing search data for the 1,000 most visited websites in the world from 2019 to 2020, we see that the absolute traffic volume increased by 22%.

What’s more is that these sites were attracting 10% of total global traffic in 2018, but that figure had doubled to 20% by the end of 2020. That traffic was predominantly mobile, with devices driving roughly 66% of all site visits last year, whilst desktop traffic share was also higher in 2020 than it was in 2018. 

This was largely due to the coronavirus pandemic, but it’s a clear sign of the global dominance of these leading sites; the bigger they are, the more traffic they will attract when more searches are being carried out on both mobile and desktop.

User Engagement Signals

Alongside the rise in traffic levels has come an apparent decline in user engagement with these sites, as behavior indicators like bounce rate and time-on-site each displayed a negative trend consistent across mobile and desktop search.

Average Time on Site: Mobile vs. Desktop

As you might expect, visits on desktop devices were 40% longer than those on mobile devices in 2020.

The average time-on-site for those desktop users actually rose by 3% in 2020, whilst the mobile equivalent continued its yearly decline. Nevertheless, users are typically spending less time on sites on average since 2018, regardless of the device they use — perhaps another sign of shortening attention spans.

Average Bounce Rate: Mobile vs. Desktop

The slight rise in time-on-site via desktop also led to an increasing average bounce rate for almost the whole of 2020.

From 2018 to 2020, visits via mobile devices had a 3% higher average bounce rate than desktop, but this gap had narrowed to only 0.2% by the end of the year, which suggests that brands need to do more to engage increasingly demanding and device-agnostic users coming from SERPs.

Mobile vs. Desktop: SERP Difference

As well as user behaviors and engagement, we looked at how this dominance of mobile is already affecting Google’s search results. 

Our analysis of the 50,000 most popular search queries in the US revealed a few signs of things to come for winners and losers in mobile-first SERPs.

URL and Domain Deviations: How Many Pages and Sites Lose Visibility in Mobile Search?

Within mobile search results, 8% of pages belong to m-dot domains, as in sites that are specifically designed for mobile devices and exist on a separate subdomain. This implies that most sites within our dataset are simply mobile-friendly.

This, however, doesn’t mean that they managed to keep their SERP positions between mobile and desktop devices.

The image below shows how many desktop pages dropped out of the top positions on mobile devices:

Out of all the pages that make it into the SERP for the analyzed keywords, only 11% maintained the same rankings across both desktop and mobile search. When we look at the same thing at domain-level, this number rose to 17%.

Moreover, a whopping 31% of URLs and 8% of domains completely disappeared from Google's search results when accessed from mobile*:

The key thing to remember here is that dropping out of top positions on mobile will have a much more dramatic effect on traffic than it will on desktop simply because of the reduced real estate available on a mobile device screen.

*The difference between the numbers of domains and URLs dropping out could be because some have both a mobile and a desktop version of the same page, but with different URLs.

SERP Features

We also analyzed Google’s mobile vs. desktop search results for any shifts in how often certain SERP features appeared:

The choice of device didn’t seem to matter for Top Stories, Local Pack and People Also Ask features, but desktop users were twice as likely to get a Google ad and a Featured Snippet, whilst mobile users saw 12.5X more images and 3X more videos in organic search.

Key Things to Consider in the Mobile-First Era

Desktop might have had a slight resurgence in 2020, but there is only one direction for our search experiences and it’s headlong into mobile. Here are three actions you can take to step into the mobile future that’s already here (you can explore mobile-first indexing in more detail in our explainer, too):

1. Gather insights about your competitors’ and industry’s traffic trends

Use tools like Semrush’s Traffic Analytics to identify market averages and benchmark the competition. If most of the key players within your niche get 60% of their traffic from mobile, but you’re only getting 30%, check your site for potential issues like slow load speeds or site architecture.

2. Assess your own mobile performance regularly and take action swiftly

Utilize Semrush’s Position Tracking to get daily data updates on your mobile rankings for target keywords within a target location. By monitoring unique metrics like Visibility (based on your SERP positions and CTR estimates) and Share of Voice (Visibility + the keyword’s search volume and traffic estimates), you can track changes in your online presence and react accordingly to outmaneuver the competition.

3. Ensure multiple touch points across devices

Don’t assume that users will only engage with you on one device; the reality is that they’ll probably use both mobile and desktop interchangeably when it comes to the purchase journey. Optimize for mobile and make it easy for people to switch to desktop to complete a purchase by letting them save shopping carts, for instance.