Unique Visitors – Understanding Your Audience

Summer is synonymous with travel, which means plenty of internet travel deals during the season. On June 7, 2016, Southwest Airlines announced that it would offer highly discounted domestic and international fares to select destinations worldwide. According to SimilarWeb data, the airline’s site experienced a massive 117% increase in desktop visits between July 6 (829,200 desktop visits) and July 8 (1.8 million visits). Desktop traffic continued to trend upward during the remainder of June and July, with average monthly desktop visits jumping from 21 million in April to 26 million in July.


The promotion clearly drove additional traffic to Southwest.com – but just how many additional visitors arrived at the site following the announcement?

SimilarWeb’s recently-launched Unique Visitors metric can provide the answer. The number of unique visitors increased by 23%, from 8.2 million in April to 10.1 million in July. Improved engagement metrics accompanied the increase in visitors, with the average visit duration rising from 07:28 to 08:14, while the number of pages per visit jumped from 7.60 to 9.14.

Understanding your Audience

Up until this point, SimilarWeb has provided the Number of Visits received by a website as a key metric for analyzing that website’s traffic. This information is critical, for example, for publishers who want to show the number of impressions an ad will receive on their website, or for the user journey team at an e-commerce website seeking to capitalize on each visit as an opportunity to convert a visitor into a purchaser.

SimilarWeb now offers a Unique Visitors metric as well. In the simplest of terms, this number represents how many pairs of eyes viewed a particular website during a specified period of time. It can help you better understand the size and reach of a website’s audience and is useful for:

  • Strategy and investment teams measuring a brand’s reach
  • Publishers assessing the exposure for a competitor’s piece of content
  • Advertisers quantifying the impact of another company’s campaign

You can view the Unique Visitors metric by clicking on the “desktop” toggle on the Website Audience – Overview page.


Dividing the number of visits by the number of unique visitors yields the number of visits per unique visitor (also provided by SimilarWeb), which can be used to analyze engagement rates on a website and understand how many times each visitor visited that website.

For example, cnn.com received 56.3 million unique desktop visitors per month between May – July 2016, with 4.69 visits per unique visitor.



Now let’s take a look at the methodology SimilarWeb uses to collect this information. There is no standard in the market for measuring the number of unique visitors, hence discrepancies between tools may exist.

SimilarWeb collects data from a variety of sources, including a large panel composed of users who share their anonymous clickstream data. Each device in the panel receives its own unique ID, which translates into a unique user. Using statistical analysis, together with a learning set, the data scientists at SimilarWeb can extrapolate the number of unique visitors to any website in the world.

Unlike other traffic analysis tools, SimilarWeb does not rely on cookies, which are often considered to be an unstable mechanism for data collection because the cookies are susceptible to manual or automatic deletion. As a result, cookie-based technologies tend to overestimate the number of unique visits; they will often show higher numbers than what appear in SimilarWeb. Learn more about SimilarWeb’s unique estimation capabilities compared to other direct measurement tools here.


What’s Next

The Unique Visitors metric is currently available for Ultimate users, and covers desktop traffic for a time frame of up to four months; one year of data will be released in the near future. In addition, we plan to offer this metric for mobile traffic as well. Contact us to learn how you can receive access to this exciting feature.

About the Author -

Josh Straus is a Marketing Communications Manager at SimilarWeb. When not immersing himself in competitive intelligence and digital marketing, Josh enjoys embarking on gastronomic adventures, climbing mountains, and studying medieval manuscripts.

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