Alexa's traffic rankings are based on the usage patterns of Alexa Toolbar users and data collected from other, diverse sources over a rolling 3 month period. A site's ranking is based on a combined measure of reach and pageviews. Reach is determined by the number of unique Alexa users who visit a site on a given day. Pageviews are the total number of Alexa user URL requests for a site. However, multiple requests for the same URL on the same day by the same user are counted as a single pageview. The site with the highest combination of users and pageviews is ranked #1.
Alexa's traffic rankings are for top level domains only (e.g. domain.com).
For more detailed information about Alexa's traffic rankings, please visit http://www.alexa.com/help/traffic_learn_more.
Alexa computes traffic rankings by analyzing the Web usage of millions of Alexa Toolbar users and data obtained from other, diverse traffic data sources. The information is sorted, sifted, anonymized, counted, and computed, until, finally, we get the traffic rankings shown in the Alexa service. The process is relatively complex, but if you have a need to know, please read on.
The traffic rank is based on three months of aggregated historical traffic data from millions of Alexa Toolbar users and data obtained from other, diverse traffic data sources, and is a combined measure of page views and users (reach). As a first step, Alexa computes the reach and number of page views for all sites on the Web on a daily basis. The main Alexa traffic rank is based on a value derived from these two quantities averaged over time (so that the rank of a site reflects both the number of users who visit that site as well as the number of pages on the site viewed by those users). The three-month change is determined by comparing the site's current rank with its rank from three months ago. For example, on July 1, the three-month change would show the difference between the rank based on traffic during the first quarter of the year and the rank based on traffic during the second quarter.
Traffic is computed for sites, which are typically defined at the domain level. For example, the Web hosts www.msn.com, carpoint.msn.com and slate.msn.com are all treated as part of the same site, because they all reside on the same domain, msn.com. An exception is blogs or personal home pages, which are treated separately if they can be automatically identified as such from the URLs in question. Also, sites which are found to be serving the same content (mirrors) are generally counted together as the same site.
Reach measures the number of users. Reach is typically expressed as the percentage of all Internet users who visit a given site. So, for example, if a site like yahoo.com has a reach of 28%, this means that of all global Internet users measured by Alexa, 28% of them visit yahoo.com. Alexa's one-week and three-month average reach are measures of daily reach, averaged over the specified time period. The three-month change is determined by comparing a site's current reach with its values from three months ago.
Page views measure the number of pages viewed by site visitors. Multiple page views of the same page made by the same user on the same day are counted only once. The page views per user numbers are the average numbers of unique pages viewed per user per day by the visitors to the site. The three-month change is determined by comparing a site's current page view numbers with those from three months ago.
Alexa Products and Services
Alexa could not exist without the participation of the Alexa Toolbar community. Each member of the community, in addition to getting a useful tool, is giving back. Simply by using the toolbar each member contributes valuable information about the web, how it is used, what is important and what is not. This information is returned to the community as Related Links, Traffic Rankings and more.
Alexa Site Information - Alexa has built an unparalleled database of information about sites that includes statistics, related links and more. All of this information can be found on Alexa's Site Overview pages, Traffic Detail pages and Related Links pages. To access these pages, simply type the URL of any site into the Alexa Search box.
Alexa Top Sites - Alexa has lists of Top Sites available by country, language or in a category. You can download a free file of the global top million sites sorted by Alexa Traffic Rank.
Site Owner Tools
Alexa has created a series of tools specifically for web site owners. These tools can help to drive traffic, make money, find broken links and more! Go to Site Owner Tools.