By Tony Nethercutt

In this two-part series about media buying for the mobile Web, I'm covering the frequently asked questions of What can I buy? How is it priced? How can I size my buy?

Last month I answered the first two questions (see column). In this column, I will cover the How can I size my buy? question. It's much easier than you might think.

As with the early days of Internet advertising we're seeing a three-stage progression of mobile media buys: Test, expand and then scale.

"Test" buys are typically in the $25,000-$50,000 range, "Expanded" buys are in the $50,000-$150,000 range and "Scaled" buys are often several hundred thousand dollars and more.

In the early days of the traditional PC Internet many sellers insisted on very large initial buys. Thankfully, we haven't seen as much of that practice in mobile, as most experienced sellers and buyers have learned that test-and-learn is a good thing.

In 2007, many agencies and advertisers moved through the test and expand phases and now, in 2008, we're seeing an increasing number of "Scaled" mobile ad buys from a variety of advertiser categories.

We're also seeing more test and expanded buys this year as advertisers who have not tried mobile yet are getting in the game since they realize their competition is already reaching customers on the mobile Web.

Agencies which buy on behalf of multiple brand advertisers are now making expanded and scaled buys for many clients in their portfolio after finding success with their initial test buys.

Because they started with test buys, they and their clients were able to get comfortable with mobile and they have moved forward with confidence and increased the size of their buys.

The process of determining the size of your test or expanded mobile ad buy is very similar to the way some advertisers are still deciding to size their buys for the traditional PC Internet.

In essence, advertisers decide how much they are willing to invest in the case that they have little idea what to expect as a return ("Test") and how much they are willing to invest if they have already tested and are willing to wade in a little deeper ("Expanded") based on past experience.

As I mentioned, expanded and scaled buys are more common now that more advertisers have tested the mobile medium.

Sizing the scaled buy
The most important things to think about when doing a scaled buy are your goals and the size of the audience you are trying to reach that is available on the mobile Web that matches your target. It sounds simple. It sounds like advertising. It is.

Nielsen Mobile reports that there are currently 40 million active mobile Web users in the United States. Of those, 53.7 percent are ages 18-34.

So, if you are looking to reach Americans ages 18-34, then approximately 100 percent of the universe you are looking to reach would be 21.5 million people.

If you multiply 21.5 million adults 18-34 by a $25 CPM, for example, then your buy would be $537,000. Following standard media buying practices, this example approximates a buy of 100 TRPs.

Mobile Internet advertising buying has come a long way in a short period of time. It is now very similar to what you already know, so you're ready to get started and test, expand and scale your buys.

Next month we'll focus on creative best practices to help you to extend your ad campaign to mobile.

Tony Nethercutt is vice president of sales at mobile advertising network AdMob, San Mateo, CA. Reach him at