Top U.S. ISPs by Subscriber:
How We Count

On this page, we show how we calculate the total U.S. ISP market and individual ISPs' market share.

by Alex Goldman ISP-Planet Managing Editor [May 4, 2006]

This table shows subscriber growth rates at the ISPs we watch:

United Online no longer claims to be only an ISP, listing the following online brands:

• Internet Access: NetZero, Juno and BlueLight Internet
• Social Networking: Classmates and StayFriends
• VoIP: NetZero Voice Web Hosting: FreeServers, 50megs, Bizhosting and Global Servers
• Premium e-mail: NetZero MegaMail, Juno MegaMail and emailMyName
• Online Photos: PhotoSite
• Premium Content: NetZero Family Pack and Juno Family Pack

Cox sold 940,000 basic cable subscribers in October, 2005. It signed an agreement to acquire some cable systems in Arizona on January 10, 2006. Of WISP competition, Cox noted in its SEC filing:

Generally, wireless cable operators are now focusing on data transmission rather than video service. One such system in Phoenix, Arizona currently serves approximately 1,500 internet service customers and competes with Cox's cable system. A wireless cable operator also is authorized to provide or is providing internet service in several California communities where Cox operates, but Cox cannot determine the number of customers it is serving.

Sprint acquired Nextel last year.

Covad's resellers made up for a decline in direct lines. ISP-Planet urges Covad to open its VoIP product to resale. EarthLink already resells Covad VoIP, but we know of no other ISP that does so.

Citizens Communications is offering triple play service:

During 2005, we also began offering a television product in partnership with Echostar's DISH Network, and at the end of 2005 we had approximately 32,000 customers buying a "triple play" package of telephone, television and high-speed internet service.

LocalNet achieved significant growth through an acquisition in December, 2005.

CenturyTel achieved its astonishing growth through several acquisitions as well as by finally publishing dialup subscriber numbers (30 percent of the total). CenturtyTel's customers are clustered in the midwest, particularly in Wisconsin, Missouri, Alabama, and Arkansas.

The market share of the top ten ISPs is now 66 percent.

Unique subscribers
In order to calculate the number of subscribers in the rest of the U.S., we have to take the number of subscriber in the U.S., provided by Jupiter Research, and subtract the number of unique subscribers in the ISPs in our list.

Jupiter Research estimates that there were 83.1 million residential subscribers in the U.S on December 31, 2006.

The ISPs in our rankings account for approximately 58,777,952 unique subscribers. We try not to count any subscriber twice. For example, a subscriber to EarthLink DSL may also be counted in Covad's DSL numbers and in the ILEC's DSL numbers as well. We therefore do not count EarthLink and Covad broadband towards our total.

We assume that 20 percent of AOL's subscriber base obtains access through another ISP, either as BYOA, or in a more traditional broadband arrangement. As AOL and Road Runner work together more and more, we expect the subscriber bases to overlap more than they do today, and hope that AOL, which is very good about disclosure, will reveal the extent of the subscriber overlap.

This leaves us with the following unique subscriber numbers:

Here's how we calculate the number of subscribers of the rest of the ISPs in the U.S. We substract the number of unique subscribers, 58,777,952, from the 83.1 million total individual subscribers. That gives us 24,322,058, or approximately 24.3 million subscribers for the rest of the ISPs in the U.S., which is 26.2 percent of the market.

Market share calculation
So how many subscribers were not unique subscribers? The total subscribership of our ISPs is 68,555,152. Of this, we believe that 58,777,952 are unique subscribers. The remainder, 9,777,200, we believe appear in the numbers of more than one ISP on our list.

In order to calculate market share, we add the remainder, 9,777,200, to the Jupiter Research subscriber total, 84,100,000, to get 92,877,200, which we use to determine the market share of each ISP. This is the total number of unique subscribers in the United States plus the number of double-counted subscribers in the ISPs listed in our table.

Here is a sample market share calcluation: AOL's apparent ISP total (including non-unique subscribers) is 19,475,000. We divide 19,475,000 by 92,877,200 to obtain the market share percentage shown on our table, 21.0 percent.

Transparency
In building subscriber rankings, we are constantly frustrated by the quality of the data we are forced to work with. We have, in contrast, endeavored to make our sources plain and our calculations obvious. We welcome feedback.

Also note that almost all companies on the list are public companies. We would like to list all providers, including non-facilities based companies, but most ISPs are privately held and do not disclose subscriber numbers at all (certainly not on a quarterly basis).

<Back to: ISP Rankings

Online Resources:
	Jupiter Research: Broadband
	Subscriber Ranking History
	Subscriber Value by Category