A) 30,000,000 US Consumers Do Mobile Banking

B) A fraction of the 30 million potential mobile banking customers have signed up for the service

C) 10% of all online banking U.S. households used mobile banking by the end of 2008 (about 46 million households currently bank online).

D) 3.1 million

E) All of the above.

It turns out that this is not an easy question to answer. As I mentioned previously on TheMoneyMashup, Bank of America claims that about 1.9 million of their customers use mobile banking. However, Celent asserts that there were only 400,000 mobile bankers in the US at the end of 2007. As for the total number of US mobile bankers in 2008, there is a very wide range of estimates.

In its banking safety scorecard compiled in November, Javelin found that just a fraction of the 30 million potential mobile banking customers have signed up for the service.

Yet this month a CNET article quoted Javelin and said that “an estimated 30 million consumers in the U.S. do mobile banking.”

The January 2009 Mobile Marketing Overview quotes Celent and asserts that “10% of all online banking U.S. households will use mobile banking by the end of 2008”. The company said that about 46 million households currently bank online. I am not a math major, in fact I even forgot how to do long division the other day, but I believe that means Celent is saying that there are 4.6 million mobile banking households.

The Wall Street Journal quotes ABI research and says that the number of mobile bankers in the US climbed to 3.1 million in 2008.

To sum it all up, we have three different research and four wildly different estimates (two different estimates by Javelin) that range from 3.1 million to 30 million. So, if you answered “E) all of the above,” you get a cookie.

Apparently determining how many US consumers use mobile banking is more of an art than a science. Some of the disparity might be explained away by how the different research reports are defining mobile banking. Perhaps some reports include any money related function – including applications not provided by traditional banks. Even so, I am not sure semantic differences can explain the whole gap. Bank of America only has 29 million online banking users. In order for Celent’s estimate to match Javelin’s, we would have to assume that each mobile banking household is made up of a little over 7 mobile banking customers. To confuse you even more, Tower Group estimates that 4.6 million consumers – not households – used mobile banking in 2008.

Does anyone have any insight into why these numbers are so far apart?